List of Contributors
vii
List of Contributors
Aydın Akbulut, Gazi University, Faculty of Science and Arts, Departmen...
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List of Contributors
vii
List of Contributors
Aydın Akbulut, Gazi University, Faculty of Science and Arts, Department of Biology, 06500 Be¸sevler Ankara, Turkey Nuray (Emir) Akbulut, Hacettepe University, Faculty of Science, Department of Biology, 06532 Beytepe, Ankara, Turkey Jurij V. Aleksandrov, Pskov Department of GosNIORH, Gorkij Street 13, Pskov, Russian Federation Margarita S. Alexevnina, Permsky State University, Perm’, Russia Claude Amoros, UMR CNRS 5023, Université Lyon 1, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France Hans E. Andersen, National Environmental Research Institute (NERI) - University of Aarhus, Vejlsovej 25, 8600 Silkeborg, Denmark N.A. Arnaut, Laboratory of Hydrogeology and Engineering Geology, Institute of Geophysics and Seismology, Moldavian Academy of Sciences, Academiei Street 3, 2028 Kishinev, Republic of Moldova Hartmut Arndt, Institute for Zoology, University of Cologne, D-50931 Köln, Germany Mikhail A. Baklanov, Permsky State University, Perm’, Russia Jürgen Bäthe, EcoRing, Graftstr. 12, 37170 Uslar, Germany Christian Baumgartner, Donauauen National Park GmbH, 2304 Orth an der Donau, Schloss Orth, Austria Serdar Bayarı, Hacettepe University, Faculty of Engineering, Hydrogeological Engineering Section, 06532 Beytepe, Ankara, Turkey Horst Behrendt, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany V.V. Bekh, Laboratory of Fish Genetics and Selection, Institute of Fisheries, Ukrainian Academy of Agrarian Science, Obukhivska Street 135, 03164 Kyiv, Ukraine Jürg Bloesch, International Association for Danube Research (IAD), Stauffacherstrasse 159, 8004 Zürich, Switzerland. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland B. Boz, Italian Center for River Restoration, Viale Garibaldi 44/A, Mestre 40173, Italy Jean-Paul Bravard, Université Lyon 2, Faculté de Géographie, Histoire, Histoire de l’art, Tourisme, 5 Avenue Pierre Mendès-France, 69676 Bron Cedex, France John E. Brittain, Norwegian Water Resources and Energy Directorate, PO Box 5091 Majorstua, 0301 Oslo, Norway. Natural History Museum, University of Oslo, PO Box 1172 Blindern, 0318 Oslo, Norway Jim Bogen, Norwegian Water Resources and Energy Directorate, PO Box 5091 Majorstua, 0301 Oslo, Norway
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Agrita Briede, Institute of Biology, University of Latvia, Miera Str. 3, 2169, Latvia Sturla Brørs, Directorate for Nature Management, 7485 Trondheim, Norway Georges Carrel, UR Hydrobiologie, Cemagref, 3275 Route Cézanne, CS 40061, F-13182 Aix-enProvence Cedex 5, France Jean-Pierre Descy, Research Unit in Organismal Biology (URBO), University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium Marie-José Dole-Olivier, UMR CNRS 5023, Université Lyon 1, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France Ivars Druvietis, Institute of Biology, University of Latvia, Miera Str. 3, 2169, Latvia Svetlana A. Dvinskikh, Permsky State University, Perm’, Russia Alcibiades N. Economou, Hellenic Centre for Marine Research, Institute of Inland Waters 46.7 km Athens-Sounion Avenue, 190 13 Anavissos, Greece Jon Arne Eie, Norwegian Water Resources and Energy Directorate, Post Office Box 5091 Majorstuen, N-0301 Oslo, Norway Tatjana V. Eremkina, Ural Institute of Water Biological Facility, Yasnaja Street 1, 620086 Ekaterinburg, Russia Per Einar Faugli, Norwegian Water Resources and Energy Directorate, Post Office Box 5091 Majorstuen, N-0301 Oslo, Norway Maria Feio, IMAR and Department of Zoology, University of Coimbra, 3004-517 Coimbra, Portugal Helmut Fischer, Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz, Germany Nikolai Friberg, Macaulay Institute, Craigiebuckler, Aberdeen, United Kingdom Aleksandra Gancarczyk, Drawa National Park, ul. Lésników 2, 73-220 Drawno, Poland Ritma Gaumiga, Latvian Fish Resources Agency, Daugavgrivas 8, Riga, 1048 G¸ ertrude Gavrilova, Institute of Biology, University of Latvia, Miera Str. 3, 2169, Latvia Yuri V. Gerasimov, I.D. Papanin Institute Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia Chris N. Gibbins, School of Geosciences, University of Aberdeen, Aberdeen AB24 3UF, UK Gísli M. Gíslason, Institute of Biology, University of Iceland, Askja-Natural Science Building, 101 Reykjavík, Iceland Manuel A.S. Graça, IMAR and Department of Zoology, University of Coimbra, 3004-517 Coimbra, Portugal Konstantinos C. Gritzalis, Hellenic Centre for Marine Research, Institute of Inland Waters 46.7 km Athens-Sounion Avenue, 190 13 Anavissos, Greece B. Gumiero, Department of Evolutionary and Experimental Biology, Bologna University, Via Selmi 3, Bologna 40126, Italy Justyna Hachoł, Wrocław University of Environmental and Life Sciences, Institute of Environmental Development and Protection, Plac Grunwaldzki 24, 50-363 Wrocław, Poland Svein Haugland, Agder Produkjon Energi AS, Service Box 603, 4606 Kristiansand, Norway Thomas Hein, University of Natural Resources and Applied Life Sciences, Vienna, Institute of Hydrobiology and Aquatic Ecosystem Management, Max – Emanuelstrasse 17, 1180 Vienna and WasserCluster Lunz, Dr. Carl-Kupelwieser-Prom. 5, 3293 Lunz/See, Austria Alan G. Hildrew, School of Biological & Chemical Sciences, Queen Mary, University of London, London E1 4NS, UK
List of Contributors
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Carl. C. Hoffmann, National Environmental Research Institute (NERI) - University of Aarhus, Vejlsovej 25, 8600 Silkeborg, Denmark Nils Arne Hvidsten, Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway Arne J. Jensen, Norwegian Institute for Nature Research, 7485 Trondheim, Norway. Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway V.M. Katolikov, Department of Channel Processes, State Hydrological Institute, 23 Second Line V.O., 199053 St. Petersburg, Russia Ludmila G. Khokhlova, Institute of Biology, Komi Science Centre, UrD RAS,167982 Syktyvkar, Komi Republic, Russia Alexander B. Kitaev, Permsky State University, Perm’, Russia Sergej K. Kochanov, Institute of Biology, Komi Science Centre, UrD RAS, 167982 Syktyvkar, Komi Republic, Russia Alexander V. Kokovkin, Institute of Social and Economic Problems of the North, Komi Science Centre, 167982 Syktyvkar, Komi Republic, Russia Ludmila G. Korneva, I.D. Papanin Institute Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia Ludmila G. Korneva, I.D. Papanin Institute Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia Brian Kronvang, National Environmental Research Institute (NERI) - University of Aarhus, Vejlsovej 25, 8600 Silkeborg, Denmark L.A. Kudersky, Department of Hydrobiology, Institute of Limnology, Russian Academy of Sciences, Sevastyanov Street 9, 196105 St. Petersburg, Russia Jan Henning L’Abée-Lund, Norwegian Water Resources and Energy Directorate, Post Office Box 5091 Majorstuen, N-0301 Oslo, Norway Nicolas Lamouroux, UR Biologie des Ecosystèmes Aquatiques, 3 bis quai Chauveau, CP 220, F-69336 Lyon Cedex 09, France Małgorzata Łapi´nska, Department of Applied Ecology, University of Łód´z, 12/16 Banacha Str., 90-237 Łód´z, Poland Valentina I. Lazareva, I.D. Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia Rob. S. E. W Leuven, Department of Environmental Science, Institute for Wetland and Water Research (IWWR), Faculty of Science, Radboud University Nijmegen, NL-6500 GL Nijmegen, The Netherlands Alexander S. Litvinov, I.D. Papanin Institute Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia N.S. Loboda, Department of Hydrology ; Odesa State Environmental University, Lvovskaya street 15, 65016 Odesa, Ukraine. B. Maiolini, Natural Science Museum, Via Calepina 14, Trento, Italy Florian Malard, UMR CNRS 5023, Université Lyon 1, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France Iain A. Malcolm, Fisheries Research Services Freshwater Laboratory, Pitlochry, Perthshire PH16 8BB, UK B. Malmqvist, Department of Ecology and Environmental Science, Umeå University, SE-90187 Umeå, Sweden Marina M. Mel’nik, Pskov Department of GosNIORH, Gorkij Street 13, Pskov, Russian Federation
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Kjetil Melvold, Norwegian Water Resources and Energy Directorate, PO Box 5091 Majorstua, U 0301 Oslo, Norway. Norwegian Water Resources and Energy Directorate, Post Office Box 5091 Majorstuen, N-0301 Oslo, Norway Natalya M. Mineeva, I.D. Papanin Institute Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia F. Moroni, Po River Basin Authority, Via Garibaldi 75, Parma 43100, Italy Isabel Muñoz, Department of Ecology, Faculty of Biology, University of Barcelona, Avenue Diagonal 645, 08028 Barcelona, Spain T. Muotka, Department of Biology, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland C. Nilsson, Department of Ecology and Environmental Science, Umeå University, SE-90187 Umeå, Sweden Victor M. Noskov, Permsky State University, Perm’, Russia Franciszek Nowacki, Polish Geological Institute, Lower Silesian Branch, Jaworowa 19, 53-122 Wrocław, Poland Alexander G. Okhapkin, Nizhegorodski State University, Nizhni Novgorod, Russia Jón S. Ólafsson, Institute of Biology, University of Iceland, Askja-Natural Science Building, 101 Reykjavík, Iceland. Institute of Freshwater Fisheries, Keldnaholt, 112 Reykjavík, Iceland Jean-Michel Olivier, UMR CNRS 5023, Université Lyon 1, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France Vaida Olšauskytè, European Commission, Joint Research Centre, Institute for Environment and Sustainability; Via E. Fermi 2749 21027 Ispra (VA), Italy Ana Ostojic’, University of Zagreb HR-10000 Zagreb Croatia
Faculty of Science Division of Biology Rooseveltov trg 6
Vladimir G. Papchenkov, I.D. Papanin Institute Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia Elga Parele, Institute of Biology, University of Latvia, Miera Str. 3, 2169, Latvia Momir Paunovic’, Institute for Biological Research 142 despota Stefana Boulevard-11060 Belgrade Serbia Morten L. Pedersen, Aalborg University, Department of Civil Engineering, Sohngaardsholmsvej 57, 9000 Aalborg, Denmark Fabian D. Peter, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland Vegard Pettersen, Statkraft Energi AS, Lilleakerveien 6, Post Office Box 200 Lilleaker, N-0216 Oslo, Norway Lars-Evan Petterson, Norwegian Water Resources and Energy Directorate, POBox 5091 Majorstuen, N-0301 Oslo, Norway Vasily I. Ponomarev, Institute of Biology, Komi Science Centre, UrD RAS, Syktyvkar, Komi Republic, Russia Elena V. Presnova, Permsky State University, Perm’, Russia Martin Pusch, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany M. Rinaldi, Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, Firenze 50139, Italy Christopher T. Robinson, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland Anna M. Romaní, Institute of Aquatic Ecology, University of Girona, Campus Montilivi 17071, Girona, Spain
List of Contributors
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Sergi Sabater, Institute of Aquatic Ecology, University of Girona, Campus Montilivi 17071, Girona, Spain Catalan Institute for Water Research (ICRA), Girona, Spain Yalçın S¸ ahin, Eski¸sehir Osman Gazi University, Faculty of Science and Arts, Department of Biology, 26480 Me¸selik, Eski¸sehir, Turkey. Svein Jakob Saltveit, Freshwater Ecology and Inland Fisheries Laboratory, Natural History Museum, University of Oslo, Post Office Box 1172 Blindern, N-0318 Oslo, Norway Leonard Sandin, Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment, 750 07 Uppsala, Sweden Martin Schneider-Jacoby, EuroNatur – European Nature Heritage Fund, Konstanzer Str. 22, 78315 Radolfzell, Germany Franz Schöll, Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz, Germany Matthias Scholten, Flussgebietsgemeinschaft Weser, An der Scharlake 39, 31135 Hildesheim, Germany Elena B. Seletkova, Permsky State University, Perm’, Russia Grigory Kh. Shcherbina, I.D. Papanin Institute Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia Galina V. Shurganova, Nizhegorodski State University, Nizhni Novgorod, Russia Rosi Siber, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland B.G. Skakalsky, Department of Environmental Chemistry, State Hydrometeorological Institute of Russia, Malookhtinsky Prospect 98, 195196 St. Petersburg, Russia ˆ Ricˇardas Skorupskas, Vilnius University, Ciurlionio g. 21/27, 03101 Vilnius, Lithuania Nikolaos Th. Skoulikidis, Hellenic Centre for Marine Research, Institute of Inland Waters 46.7 km Athens-Sounion Avenue, 190 13 Anavissos, Greece Nike Sommerwerk, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany Chris Soulsby, School of Geosciences, University of Aberdeen, Aberdeen AB24 3UF, UK. Fisheries Research Services Freshwater Laboratory, Pitlochry, Perthshire PH16 8BB, UK Gunta Spri´ng´ e, Institute of Biology, University of Latvia, Miera Str. 3, 2169, Latvia Bernhard Statzner, CNRS, Biodiversité des Ecosystémes Lotiques, 304 Chemin Creuse Roussillon, F-01600 Parcieux, France Sonja Stendera, Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment, 750 07 Uppsala, Sweden Angelina S. Stenina, Institute of Biology, Komi Science Centre, UrD RAS, 167982 Syktyvkar, Komi Republic, Russia A.N. Sukhodolov, Department of Ecohydrology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, D-12587 Berlin, Germany N. Surian, Department of Geography, University of Padova, Via del Santo 26, Padova 35123, Italy Lars M. Svendsen, National Environmental Research Institute (NERI) - University of Aarhus, Vejlsovej 25, 8600 Silkeborg, Denmark Doerthe Tetzlaff, School of Geosciences, University of Aberdeen, Aberdeen AB24 3UF, UK. Fisheries Research Services Freshwater Laboratory, Pitlochry, Perthshire PH16 8BB, UK H. Timm, Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Centre for Limnology, 61117 Rannu, Tartumaa, Estonia
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Klement Tockner, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, 8600 Dübendorf, Switzerland. Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12561 Berlin, Germany Diego Tonolla, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland Urs Uehlinger, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland. Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), CH-8600 Dübendorf, Switzerland M.A. Usatii, Laboratory of Ichthyology, Institute of Zoology, Academiei Street 1, 2028 Kishinev, Republic of Moldova Karl M. Wantzen, Limnological Institute, University of Konstanz, ATIG-Aquatic-Terrestrial Interaction Group, D-78457 Konstanz, Germany Ewa Wnuk-Gławdel, Drawa National Park, ul. Les´ników 2, 73-220 Drawno, Poland Christian Wolter, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany Margarita I. Yarushina, Russian Academy of Science, Ural Division, Institute of Plant & Animal Ecology, Street of 8 March 202, 620144 Ekaterinburg, Russia Maciej Zalewski, Department of Applied Ecology, University of Łód´z, 12/16 Banacha Str., 90-237 Łód´z, Poland. International Institute Polish Academy of Sciences – European Regional Centre for Ecohydrology under the auspices of UNESCO, 3 Tylna Str., 90-364 Łódz´, Poland. Euvgeny A. Zinov’ev, Permsky State University, Perm’, Russia Stamatis Zogaris, Hellenic Centre for Marine Research, Institute of Inland Waters 46.7 km AthensSounion Avenue, 190 13 Anavissos, Greece Vaida Olšauskyté, European Commission, Joint Research Centre, Institute for Environment and Sustainability; Via E. Fermi 2749 21027 Ispra (VA), Italy ˆ Riˆcardas Skorupskas, Vilnius University, Ciurlionio g. 21/27, 03101 Vilnius, Lithuania
List of Contributors
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Foreword
I am grateful for the opportunity to write the foreword for Rivers of Europe as it represents the European counterpart to Rivers of North America, edited by Bert Cushing and myself (Benke and Cushing 2005), and is also published by Academic Press/Elsevier. Editors Klement Tockner, Urs Uehlinger, and Christopher T. Robinson believe as we did that comprehensive description of a continent’s rivers is essential if human societies are to have any hope of understanding and wisely managing our fresh water resource and the rivers within which it flows – now and into the future. This book is important for one simple reason: fresh water is the single most important natural resource on earth. Consider that in looking for past or current life on other planets, finding evidence of water is a primary goal. Without fresh water, inland environments would be lifeless. Rivers of Europe represents by far the most comprehensive effort to describe Europe’s rivers to date. This outstanding reference contains an enormous amount of information in characterizing and synthesizing natural features of rivers and their drainage basins (catchments), including such things as climate, land use, hydrology, and biodiversity. It also highlights environmental issues of great importance to citizens and governments, including fragmentation by dams, pollution, introduction of nonnative species, and reductions in biodiversity. Although the book deals with serious issues, it will be a pleasure to read for both professional and layperson with its many beautiful maps and photographs, as well as extensive data tables that allow comparisons of physical and biological features between rivers and across regions. The editors have assembled a team more than 130 river experts from throughout Europe to describe most rivers of the continent. Included are 165 rivers from the Atlantic Ocean to the Ural Mountains and Caspian Sea. In some ways, creating Rivers of Europe surely was an even greater challenge than Rivers of North America since editors had to work with authors from many more countries and native languages. Nonetheless, this unique compendium is the result of meeting that challenge and producing what should become a standard reference for many years to come. There are interesting contrasts between North American and European rivers. The land area of Europe is roughly half that of North America, yet European rivers are found in 48 countries rather than three. Because most rivers are transboundary, the authors emphasize the particular need for using the river catchment as the key ecological/management unit, rather than political boundaries. Like North America, the diversity of European rivers is impressive, with environments ranging from the Scandinavian-Russian Arctic to mesic regions of middle Europe to arid regions of the Iberian Peninsula and Mediterranean coast. On the other hand, with a lower biodiversity of aquatic fauna in Europe, the authors’ descriptions of river-specific biodiversity, and threatened, nonnative, and extinct species serve to highlight the pressing need for conservation. Human influence on European river systems appears to have occurred earlier than in North America, with the possible exception of southern Mexico. The first alterations to European rivers were probably deforestation of floodplains, wetland drainage, and early agriculture, at least 6000 years ago. More dramatic alterations of channels, small dams, and levee-building probably did not occur in any significant way until 1000 years ago, and as the centuries passed, such activities became more widespread. Like North America, however, most significant engineering projects, particularly large dams, did not appear until the 20th century. As a result, few European rivers today are free-flowing with significant natural floodplains (only 30 of 165 described in this book), and many suffer from a wide variety of additional impacts. Given this long history and intensity of river degradation, Tockner and his collaborators emphasize the need for conservation of the few natural rivers and restoration of many others. Restoration of rivers degraded for more than a century creates a special challenge because reference conditions are non-existent in many regions. Furthermore, all conservation, restoration and management activities come with a price tag, and establishment of priorities is a major and potentially controversial task.
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The good news for European rivers is that the European Union recently began an important program called the Water Framework Directive (WFD) that requires a management plan for all major European rivers to achieve ‘‘good ecological status’’ by 2015. Rivers of Europe seems uniquely timed to be an invaluable resource to the WFD by providing a foundation for future management decisions. In general, however, the book will greatly appeal to any individual who is fascinated by rivers and will become a single major information source for river scientists, river managers, government agencies, recreationists, and conservationists within Europe and elsewhere. Arthur C. Benke The University of Alabama Tuscaloosa, Alabama, U.S.A.
Preface and Acknowledgements
Rivers traverse our landscapes and often are the major source of water for domestic, agricultural and industrial usage, power generation, navigation, fisheries, and recreation. Rivers also are a source of fascination and discovery for ecologists, hydrologists, geologists, geographers, and environmentalists. They house a tremendous source of aquatic biodiversity, much of which is highly threatened. Because of the vital role rivers play in the landscape and for society, they have been described as the circulatory system of the landscape. In spite of their undeniable and fundamental importance, there is no comprehensive treatment of the natural characteristics and diversity of European rivers nor of the extent to which human society has exploited them. With this book, Rivers of Europe, we tried to narrow this important information gap. In 2005, editors Art Benke and Bert Cushing published the benchmark book Rivers of North America. This book inspired us to compile a similar book on European Rivers. Enthusiastically, we agreed to the task - though being unaware of the major challenges awaiting us. It took almost three years from developing the first concept until completion of the book. Geographically, Europe extends from the Ural Mountains in the east to the Caucasian Alps in the southeast. There are over 150 transboundary rivers in Europe that form or cross borders of two or more countries. Europe has a total population of 780 million people with more than 100 spoken languages. The Rivers of Europe is the first reference book that covers all of Europe. In total, 136 authors from 20 countries contributed to the book, mirroring Europe’s cultural, geographic, and ecological diversity. Our first challenge was to collect comparable information on 165 European rivers, including catchments ranging from Iceland to the Peloponnese, and from the Atlantic coast in Portugal to the shores of the Caspian Sea. On the one hand, we were pleased with the wealth of available information, even for rivers that most people are unfamiliar such as those in Anatolia or northwest Siberia. On the other hand, we were somewhat surprised that even basic information on river basins such as catchment area, discharge, or water temperature was quite difficult to obtain in adequate quality. For example, published data on catchment area varies extremely, even for well-studied rivers such as the Rhine and Danube. Our second challenge was to focus at the catchment rather than country scale. While information on biodiversity or water use is mainly available at the country scale, management of river ecosystems must be done at the catchment scale. In addition, information quality differed between countries, which created a major challenge, especially for transboundary rivers. Therefore, there might be inconsistences between data presented in the individual chapters and those in the introductory chapter, where we analysed data from the same sources for all of Europe. In this respect, this book should stimulate the collection of comparative data for all of Europe and not just for the member states of the European Union. This kind of information is a pivotal requirement for setting priorities for conservation and restoration at the continental scale. We hope that the present book stimulates further research activities on European rivers, and that it supports the implementation of the EU-Water Framework Directive (WFD). The Directive is an extremely ambiguous legislative framework to protect and improve the quality of all water resources, including rivers, lakes, groundwater, and even transitional and coastal waters. The Directive states that “good ecological status” of all European rivers must be achieved by 2015. By reading about so many rivers during the past few years, we must acknowledge that most rivers already have been irreversibly transformed. Many rivers have been managed for centuries, thereby forming important elements in our cultural landscapes. In this respect, most rivers have been trained during the past decades leading to potentially irreversible damages. This book would not have been possible without the support of many people. First and foremost, we heartily thank the contributors of the chapters. It was an amazing pleasure to collaborate with so many enthusiastic and
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dedicated authors from all over Europe. We are especially grateful to Diego Tonolla, Eawag, who has devoted an immense amount of effort to the book. Diego Tonolla developed the European Catchment Data Base, digitized all the catchments, designed the maps, and was essential during the final preparation of the book. Rosi Siber, Eawag, has overseen the entire GIS effort, at the beginning of the project in particular. Special thanks goes to Fabian Peter, who developed the fish data base on European Rivers. Further, he summarized the available information on dragonflies, wetland birds, crayfish, and amphibians. We also thank Verena Keller, Schweizerische Vogelwarte, Sempach, for her support in collecting data on wetland birds, and Vincent Kalkman, European Invertebrate Survey - Nederland Nationaal Natuurhistorisch Museum - and Chair of the IUCN Odonata Specialist Group, for the compilation of the Odonata data. Additional support came from Sónia Ferreira, Cosmin-Ovidiu Manci, Elena Dyatlova, Milen Marinov, Otakar Holusa, Milos Jovic and Vladimir Skvortsov. Jörg Freyhof provided helpful information on the European freshwater fish fauna. Special thanks go to illustrator Lydia Zweifel for drawing all graphs for the book. Jan Landert, Christoph Gasser, and Barbara Köfler-Tockner assisted in the preparation of the book at various stages. We thank the many people that contributed photos that greatly enhanced the asthetics of the book. They are acknowledged in the individual chapters. The editors thank the many colleagues and authors that encouraged us and provided feedback over the past three years. We are very grateful to Andy Richford, Stephen Pegg, Emily McCloskey, and Mara Vos-Sarmiento of Elsevier/Academic Press for guiding us through the planning and execution of the project. Finally, we thank our home institutions Eawag, the Swiss Federal Institute of Aquatic Sciences and Technology, and IGB, the LeibnizInstitute of Freshwater Ecology and Inland Fisheries, for logistic and financial support. Without this support, it would have been impossible to establish the European Catchment Data Base, to design the GIS maps, and to redraw all graphs. We thank DIVERSITAS for endorsing the work presented. This book contributes to the implementation of the Science Plan of the DIVERSITAS freshwater BIODIVERSITY Cross-cutting Network. Berlin and Dübendorf, October 2008. Klement Tockner, Christopher T. Robinson, Urs Uehlinger
Chapter 1
Introduction to European Rivers Klement Tockner
Urs Uehlinger
Christopher T. Robinson
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), M€ uggelseedamm 310, Berlin, Germany Institute of Biology, Freie Universit€ at, Berlin, Germany
Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland
Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland
Diego Tonolla
Rosi Siber
Fabian D. Peter
Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland
Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland
Swiss Federal Institute of Aquatic Science and Technology (Eawag), Box 611, 8600 Duebendorf, Switzerland
1.1. 1.2. 1.3. 1.4. 1.5. 1.6. 1.7. 1.8. 1.9. 1.10. 1.11. 1.12.
1.13. 1.14.
Introduction Biogeographic Setting Cultural and Socio-economic Setting Hydrologic and Human Legacies Early and Recent Human Impact Temperature and Precipitation Water Availability and Runoff Riverine Floodplains River Deltas Water Quality Freshwater Biodiversity Environmental Pressures on Biodiversity 1.12.1. Fragmentation 1.12.2. Water Stress 1.12.3. Land Use Change 1.12.4. Non-native Fish Species The European Water Framework Directive Knowledge Gaps Acknowledgements References
1.1. INTRODUCTION Rivers recognize no political boundaries. This is particularly true for Europe, which has over 150 transboundary rivers (Whitton 1984). For example, the Danube is the 29th longest river globally, and it drains parts of 19 countries and 10 ecoregions. Further, 8 of the 10 largest catchments in Europe (Figures 1.1 and 1.2, Table 1.1) are in the eastern plains of Russia and the Ukraine and information on their present status Rivers of Europe Copyright Ó 2009 by Academic Press. Inc. All rights of reproduction in any form reserved.
is highly limited. Europe also has a long history in river training with most rivers being severely fragmented, channelized, and polluted (Petts et al. 1989; Kristensen & Hansen 1994; Tockner & Stanford 2002; UNEP 2004; Nilsson et al. 2005). Recently, the European Union launched an ambitious program called the Water Framework Directive (WFD) that requires a catchment management plan for all major European rivers for achieving ‘good ecological status’ by 2015. In this introductory chapter, we provide a comprehensive overview of all major European catchments included in the book (Figure 1.2), starting with the biogeographic setting, with an emphasis on physiography, hydrology, ecology/biodiversity, and human impacts.
1.2. BIOGEOGRAPHIC SETTING Europe forms the northwestern physiographic constituent of the larger landmass known as Eurasia. Europe covers an area of 11.2 million km2 that includes the European part of Russia, parts of Kazakhstan (Ural River Basin), the Caucasus, Armenia, Cyprus, and Turkey (Figures 1.1 and 1.2). Armenia and Cyprus are considered as transcontinental countries; and Turkey is included because of political and cultural reasons. The average altitude of Europe is 300 m asl compared to 600 m asl for North America and 1000 m asl for Asia. Only 7% of Europe is above 1000 m asl. Europe has an extensive and deeply penetrating network of water bodies. Its 117 000 km convoluted coastline facilitated easy access to the interior, and it is this feature that contributed to the rapid development of its southern shores along the Mediterranean Sea (Stanners & Bourdeau 1995; Butlin & Dodgson 1998; Hughes 2001). 1
2
PART | I Rivers of Europe
FIGURE 1.1 Topographic map of Europe and location of geographic regions covered in the book. Data sources: see Appendix.
Europe is highly diverse, both biogeographically and ecologically. The European Environmental Agency has identified 11 biogeographical regions that are considered as useful geographical reference units for describing habitat types and species that live under similar conditions (Figure 1.3A) (http://reports.eea.europa.eu/ report_2002_0524_154909/en). The biogeographic regions dataset contains the official delineations used in the Habitats Directive and for the EMERALD Network set up under the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention). In addition, Europe has been divided into 71 ecological distinct areas, based on climatic, topographic, and geobotanical data, together with the judgement of a large team of experts from several European nature-related institutions (Figure 1.3B). Ecological regions are areas with relatively homogeneous ecological conditions, within which comparisons and assessments of different expressions of biodiversity are meaningful (e.g. rivers and lakes, see also Illies 1978).
1.3. CULTURAL AND SOCIO-ECONOMIC SETTING There are distinct cultural, demographic, socio-economic, and political gradients across Europe (Bacci 1998; Hughes 2001). Today’s human population is 780 million with an average population density of 69 people/km2. At the catchment scale, the population density ranges from 15 C in the south–western part of the Iberian Peninsula, Calabria, and southern Anatolia (Figure 1.5A). The mountain ranges of the Alps and Caucasus, and the eastern Anatolian uplands (to a minor extent also the southern Carpathian Mountains and the Pyrenees) are cold islands in a relatively warm environment.
6
FIGURE 1.3 (Continued).
PART | I Rivers of Europe
7
Chapter | 1 Introduction to European Rivers
FIGURE 1.4 Changes in fluvial systems in a north–south cross-section through Europe: (b) braided (bed-load river); (m) meandering (suspended-loaded river); (m(s)): small meanders; (m(l)): large meanders. The diagram also includes the probable sequence of channel patterns for Siberian rivers.
Redrawn from Starkel (1991).
Precipitation patterns in Europe are characterized by a west–east gradient, that is decreasing precipitation with distance from the Ocean that reflects increasing continentality (Figure 1.5B). Topographic effects are superimposed on this pattern: Precipitation is high in the western front ranges of the mountains of western Britain, Norway, the western Iberian Peninsula, and low in the adjacent eastern areas (rain shadows). Areas of high precipitation (>300 cm) occur in the Alps, the adjacent northern Dinaric Alps (maximum >320 cm) and the Western Caucasus.
1.7. WATER AVAILABILITY AND RUNOFF Water availability, defined as the annual long-term average renewable water resource derived from natural discharge including consumptive water use, shows a large spatial variation among river basins. Annual water availability ranges from >1000 mm/year (western Norway, Britain’s west coast,
southern Iceland) to 1/3 to the total continental runoff (Table 1.1). The average annual specific runoff ranges from 68 mm/year (Asi River in southeast Turkey) to 1150 mm/year (Tay River in Scotland). High seasonality in runoff is typical for rivers in southern Europe and Turkey such as the Guadalquivir (Iberian Peninsula) and Upper Euphrates, and for Boreal and Arctic rivers such as the Glomma (Norway) and Pechora (Russia). Low runoff variability is characteristic for central European rivers (e.g., Elbe) and Steppic rivers (e.g. Dnieper) (Figure 1.6).
8
PART | I Rivers of Europe
FIGURE 1.5 Mean annual air temperature (A) and mean annual precipitation (B) across Europe. Locations of the geographic regions covered in the book are indicated. Data sources: see Appendix.
Chapter | 1 Introduction to European Rivers
FIGURE 1.6 Seasonal distribution in catchment runoff (L/s/km2) for selected rivers distributed across Europe. Runoff includes the difference between precipitation, evapotranspiration and catchment topography (Data source: Global Water Runoff Data Center, GRDC, http://grdc.bafg.de/servlet/is/2781/? lang=en).
9
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PART | I Rivers of Europe
1.8. RIVERINE FLOODPLAINS Due to the development of agriculture in alluvial plains, the transformation of rivers to waterways for navigation, and the protection of settlements, floodplains have been ‘trained’ for centuries. Today, about 50% of the total European human population lives on former floodplains. As a consequence, 50% of the original wetlands and up to 95% of riverine floodplains have been lost. In 45 European countries, 88% of the alluvial forests have disappeared from their potential range (Hughes 2003). The Seine River (France, not covered in the book) shows the highest impact of all European rivers with 99% of its former riparian floodplains lost. Of the former 26 000 km2 floodplain area along the Danube and its major tributaries, 20 000 km2 have been isolated by levees and have thus become ‘functionally’ lost; meaning that the basic attributes that sustain floodplains such as regular flooding and morphological dynamics are missing (Klimo & Hager 2001). Switzerland has lost about 95% of its original floodplains over the last two centuries. The remaining floodplains included in the inventory of ‘floodplains of national importance’ are far from being pristine, being heavily influenced by water abstraction, gravel mining, and fragmentation. Today, the largest remaining floodplain fragment in Switzerland covers an area of only 3 km2. Because most European floodplains are already ‘cultivated’, even impacted systems that retain some natural functions, such as those along the Oder River (Poland/Germany), the Danube River, and eastern European river corridors, are extremely important to protect. This is especially true for river corridors in Eastern Europe because of ever
increasing pressures from development (gravel exploitation, damming, dredging for navigation, road construction) (Tockner & Stanford 2002).
1.9. RIVER DELTAS Deltas are integral features of many catchments, being important depositional landforms where the river mouth flows into an ocean, sea or lake. The geometry, landform, and environment of deltas result from the accumulation of sediments added by the river and the reworking of these sediments by marine or lake forces. Because many European rivers discharge into isolated, inland seas (Baltic, Black and Mediterranean Seas) characterized by low tides and moderate wave powers, they can form extensive deltas (Table 1.2, Figure 1.7). 35 important European deltas cover a total area of 90 000 km2. Despite their ecological and socioeconomic importance, European deltas are among the least investigated aquatic ecosystems. Deltas are highly productive environments and, as a consequence, they have been extensively transformed into cropland and urban areas. Today, the human density in European deltas is often much higher than in respective upstream catchment (Tables 1.1 and 1.2), although the opposite pattern can be found such as for the Danube and some tributaries to the White Sea. Deltas formed by the Pechora, the Northern Dvina (despite having a large seaport, Archangelsk, with a population of 350 000), and the Volga are among the few remaining relatively pristine deltas. Deltas are biologically diverse ecosystems, thus major efforts are underway to conserve and
TABLE 1.2 Twenty of the largest river deltas in Europe (including Turkey and the Caucasus).
Rhine Volga Ural Pechora Kuban Danube Kura Terek Po Dnieper N Dvina Guadalquivir Seyhan Vistula Rhone Nemunas Don Kızılırmak Ebro Nestos
Area (km2)
Average temperature ( C)
Population (people/km2)
Arable and Pasture (%)
Protected (%)
25 347 11 446 8586 5490 5422 4560 4175 4026 2878 2833 2229 2213 1903 1858 1783 1088 604 474 331 319
9.2 10.3 9.1 4.0 11.7 10.7 15.5 11.6 12.8 8.7 0.6 17.6 17.1 7.7 13.5 6.7 10.1 11.1 15.9 12.5
492 53 24 20 000 >1000 >130 300 >13 000 5504 1800
50 163 400 902 350 350 150 423 1724 129 1077 4050 5 74 6 400 74 253
5 4 20 43 21 15 m) Native fish species Nonnative fish species Large cities (>100 000) Human population density (people/km2) Annual GDP ($ per person)
Middle Volga
Lower Volga
Mologa Sheksna (Upper (Upper Volga) Volga)
162 201 88 150 236 268 973 712 221 316 37 462 49.57 244.40 253.86 7.47 66.1 58.7 40.5 69.1 3.5 3.1 6.4 3.6 2 8 4 2 59; 60 28; 59 55 60
145 19 445 5.68 63.1 3.1 1 60
Unzha Oka (Upper (Middle Volga) Volga)
Sura Vetluga Kama (Middle (Middle (Middle Volga) Volga) Volga)
Samara Bol’shoi Irgiz (Lower (Lower Volga) Volga)
158 28 941 4.98 61.6 2.8 2 60
201 67 018 6.69 55.1 4.4 3 28
143 38 974 8.04 59.9 3.1 2 60
160 46 950 1.58 47.3 4.3 2 55
89 24 542 1.12 42.3 5.7 1 55
169 245 000 39.2 60.5 4.8 4 28; 59
233 516 891 104.07 58.7 2.0 7 60
0.3 24.4 6.7 57.6 0.0 0.0 6.5 4.5
1.1 49.5 0.2 46.2 1.5 0.0 0.0 1.5
1.1 54.8 21.5 16.6 2.4 0.0 0.0 3.6
0.1 24.5 7.3 48.5 0.0 0.0 14.5 5.1
0.2 24.5 0.7 54.8 0.0 0.0 3.7 16.1
0.2 12.4 0.2 85.7 0.0 0.0 0.9 0.6
2.1 53.6 10.3 32.1 0.0 0.0 1.5 0.4
1.2 71.9 0.1 25.8 0.9 0.0 0.0 0.1
0.5 31.5 2.0 61.7 0.0 0.0 4.3 0.0
0.5 35.2 0.2 61.6 1.0 0.0 0.0 1.5
1.0 73.5 3.7 19.2 2.4 0.0 0.0 0.2
0.6 40.6 36.1 19.8 2.6 0.0 0.0 0.3
6.1
5.2
7.0
8.0
11.7
3.1
5.1
4.2
2.9
5.1
1.7
5.1
1.0 1.0 3 4 42 14 2 23 3137
1.3 1.3 3 2 45 19 18 52 2206
1.3 1.3 3 2 45 17 8 40 2045
1.1 1.1 1 0 n.d. n.d. 2 38 1727
1.0 1.0 1 0 n.d. n.d. 0 9 2188
1.0 1.0 1 0 n.d. n.d. 2 27 2149
1.1 1.1 1 0 n.d. n.d. 0 9 2016
1.0 1.0 1 0 n.d. n.d. 0 9 2916
1.0 1.0 3 1 21 1 0 29 3058
1.0 1.0 1 0 n.d. n.d. 0 5 3138
2.0 2.0 1 0 30 9 10 113 2882
1.0 1.0 3 3 36 5 6 56 2027
Chapter | 2 Volga River Basin
TABLE 2.1 General characterization of the Volga River Basin
n.d.: No data. For data sources and detailed explanation see Chapter 1.
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2.5. GEOMORPHOLOGY, HYDROLOGY, AND BIOGEOCHEMISTRY 2.5.1. Geomorphic Development of the Main Corridor The river network of the Volga looks like a branching tree in the north that evolves into a single trunk rooting as a delta in the Caspian Sea in the south. The lower Volga is divided into many side-arms and the 515-km long Akhtuba is the largest. The delta at the confluence of the Volga and Caspian Sea occupies a total area of 11 446 km2. Twelve large reservoirs with a total storage of 168 km3 and total area >23 000 km2 are found in the catchment, nine of these directly on the Volga River (Table 2.1). Most of the Volga from the town of Tver’ to Volgograd is affected by an uninterrupted cascade of eight large shallow reservoirs, considerably slowing the flow velocity of the river. The reservoirs differ in terms of morphometry, optical regime, chemistry, lateral inflow, water exchange and trophic status (Avakyan et al. 1987; Butorin & Mordukhai-Boltovskoy 1979; Mineeva 2004).
2.5.1.1 The Upper Volga The Upper basin is boreal, covering about 236 000 km2. The source of the Volga is in the Valdai Hills at 228 m asl, occurring as a small brook flowing from a bog through the lakes Malyi Verkhit and Bolshoi Verkhit. It then flows through a chain of lakes (Sterzh, Vselug, Peno and Volgo) that form Verhnevolzhskoe reservoir used to store water for navigation in the Upper Volga. The Verhnevolzhskaya dam was built below Lake Volgo in 1843, and completely rebuilt in
PART | I Rivers of Europe
1943–1947. Major rivers flowing into Verhnevolzhskoe reservoir include the Runa, Kud’ and Zhukopa. Below Verhnevolzhskaya dam the Volga flows through the Valdai Hills, decreasing from 200 to 150 m asl within 70 km. The Volga between Selizharovka junction and the lowlands is known as the rapids, having >20 rapids and shallows. The Volga enters the Verhnevolzhskaya lowland downstream of the town of Rzhev, becoming relatively rich in water. Below the mouth of the river Vazuza, the Volga turns sharply to the north and then northeast, flowing through the vast Verhnevolzhskaya lowland within the coniferous broad-leaf forest biome. The next 145 km of the Upper Volga reside in Ivankovo reservoir (Photo 2.1), the 1st stage in the Volga-Kama cascade chain, and lies within the coniferous–deciduous subzone of the forest biome. Forests cover 39% of the catchment area, bogs 2.8%, and lakes 2.2%. The main role of Ivankovo reservoir is water supply, typically discharging 57% of its total input. Major tributaries of the reservoir include the Tvertsa, Shosha and Lama, contributing 35.7% of the total inflow to the reservoir (Vikulina & Znamensky 1975; Butorin & Ekzertsev 1978). Below Ivankovo reservoir, the Volga turns northeast. In this area, the lowland is bordered on the southeast by the Klin-Dmitron ridge and the Uglich and Borisogleb uplands. The elongate Uglich reservoir was constructed here in 1940. The reservoir lies in the forest belt, mainly in the coniferous– deciduous forest biome. The northern part extends into the southern taiga biome. Forests occupy 42% of the basin area, bogs 11%, and lakes 2% (Vikulina & Znamensky 1975). The river from Uglich to the Rybinsk hydroworks flows along the southern Volga part of Rybinsk reservoir, and PHOTO 2.1 Upper Volga: bank of the Inankovo reservoir (Photo: N. Mineeva).
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Chapter | 2 Volga River Basin
represents the 3rd stage in the Volga cascade system. The reservoir was filled after dam construction across the Volga River near Perebory and across the Sheksna River near Rybinsk. Rybinsk reservoir lies in the southern taiga biome of the forest belt, occupying the vast Mologa-Sheksna lowland. The Rybinsk reservoir flooded river channels and their floodplains, upper floodplain terraces, and the vast watershed between the Mologa and Sheksna Rivers. Forests occupy 52% of the basin area, bogs 9.5% and lakes 5.5%, respectively. Altogether, 64 rivers flow into Rybinsk reservoir (Vikulina & Znamensky 1975). The 448-km long river section between the towns of Rybinsk and Gorodets occupies the 4th stage in the Volga cascade system, represented by Gorky reservoir within the southern taiga biome of the forest belt. The upper part of this section between Rybinsk and Yaroslavl is a valley type river, whereas the middle part around the Kostroma confluence forms the lacustrine Kostroma expansion. The Unzha and Nemda Rivers flow into the reservoir along the border between Yurievets and Gorky dam. Forests occupy 57% of the basin area, bogs 6.3%, and lakes 4.4% (Vikulina & Znamensky 1975). Gorky dam acts as a border between the upper and middle Volga. The upper Volga network is best developed in the north, west, and northeast areas of the basin. Although the exact number of small rivers cannot be counted, the four major tributaries, Kostroma, Sheksna, Mologa and Unzha have basin areas from 17 100 to 37 462 km2 and annual discharges of 5–7.5 km3. All other basins occupy between 1000 and 7000 km2. Most tributary rivers are 100–400 km long, although 13 of these are shorter. Information on
discharge is available for 24 rivers and 17 of these have an annual discharge 50% of the annual flow in spring from snowmelt. Discharge in summer and autumn are essentially the same, and a minor increase in discharge occurs in October and November from precipitation. In winter the discharge is low and rarely exceeds 10% of the total annual flow. Interannual variation in water exchange ranges from 3.4 to 17.9 per year in the upper Volga, 4.1–24.3 per year in the middle Volga, and 5.4–23.8 per year in the lower Volga. The Rybinsk reservoir has the lowest water exchange in the Volga cascade system.
stations. Reservoir drawdowns show wide daily and weekly variation, and flow velocities can change by an order of magnitude below reservoir dams.
2.5.2.3 Water Temperature The temperature regime of the Volga is typical of most waters in the boreal zone, following the seasonal pattern in heat input (Figure 2.3). Water temperature generally increases downstream, although sometimes being higher than air temperature in the north and lower in the south. Reservoirs also changed the thermal regime of the Volga. For instance, the average duration of ice-cover increased by 8–20 days and now ranges from 158 days in the upper Volga to 101 days in the lower Volga. However, ice-cover duration has decreased from 90 to 70 days in its lowest section near the city of Astrakhan. In winter, temperatures within flowing reaches and shallow reaches are lowest and most uniform with depth. In deep lake-like areas, temperatures depend on heat exchange between the water and bottom sediments. A gradual increase in temperature due to heat emission of sediments leads to increases in water heat storage and reservoir stratification. The most intensive warming occurs during the spring flood from mid May to early June. Accumulation of spring runoff water in reservoirs and the loss of winter water below dams decrease temperatures by 0.8–2.4 C in the lower Volga and increases water temperatures in the upper Volga. At the end of spring runoff, thermal stratification of water usually develops in reservoirs, but the timing is short and stratification is unstable. Temperature gradients observed at depths of 2–4 m are on average 1–3 C/m. Monthly average temperature of the surface layer is maximum in July, while the total water storage temperature is maximum in August. The seasonal temperature decrease begins in late August and is most intensive in September, especially in the upper Volga (Figure 2.3). Long-term records show an increase in mean water temperature since the late 1970s (Figure 2.4). The Volga contributes on average 104 1017 J of heat per year to the Caspian Sea, and flow regulation has decreased the inter-annual fluctuation in heat runoff.
2.5.2.2 Current Reservoir construction dramatically altered the flow regime in the Volga due to current velocity decreases in the impounded water-bodies. Under natural conditions, mean velocities in the southern part of the upper Volga during low summer flows ranged from 0.26–0.32 m/s in deep areas to 0.50–0.70 m/s over shallow bars. During the annual spring flood, velocities increased to 1.50–1.70 m/s, decreasing to 1.25 m/s post flood. Flood velocities can reach 0.85 m/s in summer and 0.96 m/s in winter (Butorin & Mordukhai-Boltovskoy 1979). Currents in the present Volga system are complex, as river flows are influenced also by convective flows and wind effects formed in the reservoirs. As such, water circulation in the river depends on reservoir morphology and the interaction of these different factors. For instance, river channels dominate the morphology of Ivankovo, Uglich, Gorky, Saratov and Volgograd reservoirs, whereas the total water input governs hydrodynamic processes. Here, the highest flow velocity usually occurs during the spring flood and velocities decrease to a minimum in summer. Flow velocities become considerable again under ice-cover in winter. In contrast, wind effect and bottom relief strongly influence hydrological conditions within the more lake-like Rybinsk and Kuibyshev reservoirs. Regardless, the head and tailwaters of reservoirs have distinctive current regimes due to activities of power
Temperature [°C]
25
Upper
Middle
Lower
20
15
10
5 May
June
July
Aug
Sept
Oct
FIGURE 2.3 Annual temperature regime for the upper, middle, and lower Volga.
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Chapter | 2 Volga River Basin
FIGURE 2.4 Long-term temperature records for the Volga.
14
12
1950
1960
1970
1980
1990
2000
2.5.3. Biogeochemistry 2.5.3.1 Mineralization The superfluous nature of the Volga results in relatively low water mineralization along the river. Total mineralization decreases with increasing discharge during spring runoff and high flows from rain, and increases during winter and summer low flows. Headwaters in the upper Volga are hydrocarbonate streams with low content of alkaline metals, chloride, and sulphate. Average mineralization values range from 100–270 mg/L in summer to 300–400 mg/L in winter. Mineralization decreases downstream of Rybinsk dam (Kopylov 2001). In the middle Volga, the Oka River adds highly mineralized waters that have a high content of strong acidic ions. For instance, the average sulphate concentration in the Oka typically exceeds that in the Volga by 4–6 times, whereas hydrocarbonate concentrations are lower. Downstream of the confluence with the Oka, chemical stratification of the two rivers is evident although mixing increases towards the mouth of the river Sura. Downstream of the confluence with the Oka, mineralization in the Volga ranges from 150– 340 mg/L in spring and summer to 220–400 mg/L in winter (Butorin & Mordukhai-Boltovskoy 1979). Downstream of the Kama confluence, calcium and hydrocarbonate remain high, but chloride increases twofold and the concentration of alkaline metals also increases. The total amount of chloride and sulphate is almost equal that of hydrocarbonate. Here, mineralization varies from 180–380 mg/L in summer to 480–560 mg/L in winter. Lateral inputs in the lower Volga are small and the salt composition of the water remains similar to those below Kuibyshev reservoir. Intra-annual variation in mineralization in the lower Volga is low with average May–October values of 160–420 mg/L and winter values of 230–470 mg/L (Butorin & Mordukhai-Boltovskoy 1979). Long-term trends indicate an increase in total mineralization of Volga waters (Figure 2.5).
2.5.3.2 Suspended matter High flow velocities within the river, as well as susceptibility to wind mixing in reservoirs, result in high levels of suspended matter in the Volga that affects water transparency. The amount and composition depends on the contribution from alluvial drift, reformation of riverbanks and beds, and
phytoplankton production. Suspended matter content varies from 2 to 35 mg/L. Seasonally, turbidity is typically maximal during spring runoff, minimum in winter, and with periodic increases in summer and autumn from precipitation events. Prior to flow regulation, water transparency generally decreased downstream, whereas presently transparency is higher in the lower Volga.
2.5.3.3 Water colour Water colour is associated with the content of humic organic matter. Due to features of the catchment area and decreased lateral inflow, water colour in the Volga decreases from north to south. Based on colour values, waters of the upper Volga are mainly mesohumic and meso-polyhumic. Occasionally, polyhumic waters with colour >100 Pt–Co degree can be found. Seasonally, water colour is highest during spring runoff with peaks in colour after heavy rains. Water colour is lower below Rybinsk dam and further downstream in the middle and lower Volga. Here, water colour corresponds to a mesohumic type in the Middle basin and to mesohumic and oligohumic type in the lower basin.
2.5.3.4 Dissolved oxygen In spite of flow regulation, the oxygen regime in the Volga remains favourable for hydrobionts and dissolved oxygen (DO) is rather high. Vertical gradients in oxygen are rare, occurring only under ice cover in shallow floodplain areas where DO content can become low enough to kill fish. During the ice-free period, DO content usually is 8–9 mg/L (75–100% saturation). Dissolved oxygen can become super-saturated near the surface during peaks in phytoplankton growth.
250 Mineralization (mg/L)
Temperature (°C)
16
200
150 1950
1960
1970
1980
1990
FIGURE 2.5 Long-term changes in mineralization in the Volga.
2000
34
PART | I Rivers of Europe
2.5.3.5 Bottom sediments
2.5.3.7 Pollution
Before flow regulation, bottom sediments of the Volga down to the confluence with the Sheksna River were stony mixed with coarse sand. Following regulation, the riverbed became gradually sandier. Downstream from the confluence with the Kama, bottom sediments were dominated by fine sand with areas of clay; areas of stony sediments were rare, and loam and mud sediments were deposited in deeper areas. The bed was covered with a mixture of loam, mud and sand sediments in side-arms of the delta having slow currents (Butorin & Mordukhai-Boltovskoy 1979). Sands and transformed soils are the most typical sediments in the littoral of the upper Volga, while grey clay silts cover deep channel areas. Brown and white silts are common in the middle and lower Volga, especially in areas of bank failure (Kopylov 2001; Zakonnov 2005). Transformation of riverbed sediments began with the filling of the reservoirs. Early on, the abrasive action of water masses caused destruction of shorelines and erosion of the streambed. At the same time, transported suspended matter deposited on the reservoir bottom formed secondary deposits that are now the main constituents of reservoir bottoms. The distribution of various sands characterizes the bed sediments of most reservoirs with grey muds common in areas next to the main channel. Muddy deposits predominate in the more lacustrine areas and near dams. The mean rate of deposition was estimated to be 1.7– 2.5 mm/year (Butorin & Mordukhai-Boltovskoy 1979). Today, the mean rate of deposition in reservoirs is 1.9– 3.8 mm/year. These secondary deposits range from 85– 300 cm in the upper Volga, 110–120 cm in the middle Volga, to 65–85 cm in the lower Volga (Zakonnov 2005).
Industrial and agricultural developments in the basin have resulted in an annual discharge of about 21 km3 of waste-water, including 11 km3 of untreated or insufficiently treated wastes. Annually, about 350 000 tons of nitrates, 90 000 tons of phenols, 521 000 tons of sulphates, 384 000 tons of chlorides, and 87 000 tons of organic matter are discharged with the wastewater. The atmosphere of the Volga basin receives 20.6 million tons of toxic substances (Lukyanenko et al. 1994; Komarov 1997, http://www.biodat. ru/doc/biodiv/part6b.htm). Serious pollution problems in the Volga catchment are associated with water abstraction for irrigation, industrial and municipal needs. In 1993, total consumption of freshwater in the Volga catchment was 34 billion m3: 47% for municipal needs, 29% for industrial production, and 24% for agriculture. The state of aquatic resources in the catchment indicates both qualitative and quantitative degradation that poses a serious threat to aquatic and terrestrial ecosystems (Avakyan 1998).
2.5.3.6 Nutrients Following flow regulation, the Volga maintains relatively high nutrient loads favourable for growth of phytoplankton. Anthropogenic inputs from the surrounding landscape sustain high levels of total phosphorus (TP) and total nitrogen (TN) in the river. Seasonally, little variation was found for TP or TN during the ice-free period in Rybinsk reservoir. Nutrient re-suspension from bottom sediments also occurs in open, large, shallow areas subject to wind mixing. In terms of inorganic nutrients, nitrate and phosphate are high in concentration. Mineral nutrients decrease substantially during phytoplankton blooms, becoming higher after elimination of algae. Total phosphorus content averages 71–139 mg/L and TN 0.88–1.32 mg/L with the highest values of both nutrients found in the middle Volga. Here, TN may be as high as 2.16 mg/L. Long-term trends show an increase in nutrient content from the river into the Caspian Sea. Indeed, TP has increased by 89% and TN has increased by 48% from 1935 to 1985. During the last 15 years, TN and TP have decreased, although nitrate and phosphate continued to increase.
2.6. AQUATIC AND RIPARIAN BIODIVERSITY 2.6.1. Upper Volga 2.6.1.1 Plants The upper Volga basin is located in the zone of southern taiga forests. Vegetation of the river and its littoral is diverse. Representative vegetation in the basin is a combination of osiers (Salix acutifolia, S. triandra, S. viminalis), oak (Quercus robur) and black alder (Alnus glutinosa) forests. Widely distributed are meadows covered by red fescue grass (Festuca rubra), foxtail (Alopecurus pratensis) and creeping bent grass (Agrostis alba). Lower areas of the floodplain are dominated by communities of reed canary grass (Phalaroides arundinacea) and narrow-leaved sedge (Carex acuta) (Isachenko & Lavrenko 1980). Riverbanks alternate between thickets of willow (S. triandra, S. cinerea) and P. arundinacea. Gentle wet banks and dry shoals in bays are dominated by thickets of manna grass (Glyceria maxima), narrowleaved sedge (C. acuta), and swamp horse-tail (Equisetum fluviatile). Periodically, there are growths of reed (Phragmites australis) and bulrush (Scirpus lacustris). In the river channel, pondgrasses (Potamogeton pectinatus, P. perfoliatus) prevail. Aquatic vegetation is more diverse in reaches of rivers and bays of reservoirs in the upper Volga. Here, Batrachium circinatum, Ceratophyllum demersum, Myriophyllum spicatum, Nuphar lutea, Nymphaea candida, P. lucens, and P. natans dominate. At some sites occur the North American introduced species Elodea canadensis. Overall, the flora of the upper Volga and its reservoirs is represented by 138 species of higher aquatic plants.
35
Chapter | 2 Volga River Basin
2.6.1.2 Algae On the basis of published (Yakovlev 2000) and unpublished data from 1953 to 2004, 1329 phytoplankton species or 1609 species, varieties and forms have been identified in the upper Volga. Green algae (571) and diatoms (340) are taxonomically the most diverse planktonic algae. The greatest diversity of algae (983 species) has been found in Rybinsk reservoir, it having a vast littoral zone. The total number of algal species in Gorky reservoir is 754, 672 in Ivankovo reservoir, and 412 in Uglich reservoir. Diatoms and blue-greens show major seasonal and longterm phytoplankton dynamics in the upper Volga reservoirs (Lyashenko 1999, 2000; Okhapkin et al. 1994; Kopylov 2001). Three peaks in diatom biomass occur during the open water season, that is spring, summer and autumn, with a maximum peak in spring. Major species include Aulacoseira islandica (O. M€ ull.) Sim., A. subarctica (O. M€ ull.) Haworth, A. ambigua (Grun.) Sim., A. granulata (Ehr.) Sim., Stephanodiscus hantzschii Grun., S. minutulus (K€ utz.) Cleve et M€ uller, S. neoastraea (Hak. et Hickel) emend. Casper, Scheffler et Augsten, Stephanodiscus binderanus (K€utz.) Krieg., S. invisitatus Hohn et Heller., Asterionella formosa Hass., Diatoma tenuis Agardh., Skeletonema subsalsum (A. Cl.) Bethge., and at times Fragilaria crotonensis Kitt., F. capucina Desm., Synedra ulna (Nitzsch.) Ehr., S. acus K€utz., and Melosira varians Ag. Small-celled algae typical of waters with high organic content such as genera Stephanodiscus: S. hantzschii and S. minutulus, as well as the brackish water species Skeletonema subsalsum were common in the 1960s. These species appeared along the entire Volga following completion of the main hydro-engineering works. S. subsalsum invaded the Volga from the south, and belongs to the Ponto-Caspian group. In the 1990s, the appearance of the brackish-water Actinocyclus normanii (Greg.) Hust. was registered in Rybinsk reservoir (Genkal & Yelizarova 1996). It entered from the Baltic and Caspian Sea basins. Since 2000, this species has been actively spreading in Rybinsk and Gorky reservoirs. In 2000, the diatoms Cyclotella radiosa (Grun.) Lemm. and Cyclostephanos dubius (Fricke) Round began to dominate phytoplankton of Ivankovo and Rybinsk reservoirs. These species are common algae in Sheksna reservoir located to the north. In the 1980s, Cyclotella meneghiniana K€ utz. was an important component of the phytoplankton community in Rybinsk Reservoir. From 1980 to 2000, Stephanodiscus binderanus disappeared as a dominant alga in Ivankovo and Uglich reservoirs. Cyanobacteria (blue-greens) develop mainly in summer. Summer blooms of Aphanizomenon flos-aquae (L.) Ralfs, Microcystis aeruginosa (K€ utz.) K€ utz., M. wesenbergii (Kom.) Kom., M. holsatica (Lemm.) Lemm and at times Anabaena species have been recorded. In the 1960s, nonheterocystous cyanobacteria Planktothrix agardhii (Gom.) Anag. et Kom. and mixotrophic cryptomonads were common in Ivankovo reservoir. The abundance of cryptomonads
(species Cryptomonas, Chroomomas acuta Uterm.) increased in the 1970s in Rybinsk reservoir, and during the 1990s these algae began to dominate Gorky reservoir. In Uglich reservoir in the 1990s, P. agardhii became common in phytoplankton samples. The green algae Coelastrum, Pediastrum, Scenedesmus, Sphaerocystis, Schroederia, Mougeotia, Chlamydomonas, Carteria and Pandorina morum (O. M€ull.) Bory generally prevail in summer phytoplankton communities. The greatest diversity of green algae is noted for Rybinsk reservoir. In 2000, development of motile species of the genera Chlamydomonas, Carteria and P. morum increased here. Mean annual phytoplankton biomass during the ice-free period of 1954–2001 increased from 0.5 to 3.4 g/m3. Maximal values were recorded in the 1970s in the highly eutrophic Ivankovo reservoir, and highest biomasses were recorded in summer and in spring.
2.6.1.3 Zooplankton Zooplankton in the upper Volga consists of about 400 species, mainly Cladocera, Copepoda and Rotifera. The last group dominates the community, making up >60% of the total species number (Butorin & Mordukhai-Boltovskoy 1979; Kopylov 2001). Two seasonal maxima in zooplankton can be observed. Cladocera make up 60–70% of the total biomass in June, while the Copepoda (up to 80% of biomass) prevail more often during late summer in August. The most abundant and wide spread are the Crustacea Bosmina longispina Leydig, B. coregoni (Baird), B. longirostris (O.F. M€uller), Daphnia galeata Sars, D. cucullata Sars, D. cristata Sars, Chydorus sphaericus (O.F. M€uller), Mesocyclops leuckarti Claus, Thermocyclops oithonoides (Sars), Cyclops kolensis Lilljeborg, C. vicinus Uljanin, Eudiaptomus gracilis Sars, Heterocope appendiculata Sars, Leptodora kindtii (Focke), Bythotrephes longimanus Leydig, and Rotifera Asplanchna priodonta Gosse, Conochilus hippocrepis (Schrank) and C. unicornis Rousselet. Since the 1980s, larvae (veliger) of the mollusk Dreissena polymorpha Pallas were common in Ivankovo and Uglich reservoirs, making up 1.3–1.5 million organisms/m3 in the mid-1990s (Stolbunova 1999). The dominating complex of zooplankton is quite variable, changing every 10–20 years. At present, two groups can be distinguished among nonnative species. The first group includes northern lacustrine forms Heterocope appendiculata, Eudiaptomus gracilis, E. graciloides Lilljeborg, Cyclops kolensis, Limnosida frontosa Sars, Daphnia longiremis Sars, D. cristata, Bosmina longispina, Bythotrephes longimanus that entered the upper Volga from lakes Volgo, Peno, Vselug and Sterzh, and Lake Beloye on the river Sheksna even before regulation. These species presently make up the main part of the total species number. The second group includes species recently introduced in the Volga. The northern species Arctodiaptomus laticeps Sars appeared in Rybinsk reservoir in 2004 probably from Lake Beloye and is still rare.
36
PART | I Rivers of Europe
Southern species such as Asplanchna henrietta Langhaus, Diaphanosoma orghidani Negrea and Acanthocyclops americanus (Marsh) moved into the upper Volga in the 1980s. The number of A. americanus has sharply increased since the early 1990s. An expansion of Asplanchna henrietta and Diaphanosoma orghidani has begun since 2003–2004, and now they are common forms of plankton. However, high numbers (3–15 000 organisms/m3) are found only occasionally (Stolbunova 1999; Kopylov 2001; Gusakov 2001). Zooplankton abundance differs significantly between different sites in the catchment. Mean seasonal (May– October) abundance is 350–400 000 organisms/m3 in Ivankovo and Uglich reservoirs (Stolbunova 1999). In Rybinsk and Gorky reservoirs, abundances do not exceed 4– 116 000 organisms/m3. Mean zooplankton biomass varies from 90% of zoobenthic numbers in deep water reaches. The larvae of Chironomidae (Chironomus muratensis Ryser et al., Lipiniella araenicola Shil., Stictochironomus crassiforceps (K.), Polypedilum bicrenatum K., Cladotanytarsus mancus (Walk.) as well as the oligochaete T. newaensis and amphipod Gmelinoides fasciatus (Stebb.) dominate shallow waters. Five macroinvertebrates including two Coleoptera species (Ditiscus latissimus L. and Graphoderus bilineatus (Deg.), Odonata (Leucorrhinia pectoralis (Charp.), and two mollusks (Anisus vorticulus Troschel and Unio crasus Philips) are under danger of extinction. Several Ponto-Caspian introductions (non-indigenous benthic species) inhabit the upper Volga at present. They are the mollusks Dreissena polymorpha, D. bugensis, and Lithoglyphus naticoides Pfeiffer, polychaetes Hypania invalida Grube, oligochaetes Potamothrix heusheri (Bret.) and FIGURE 2.6 Changes in the biomass of phytoplankton (A), zooplankton (B), and zoobenthos (C) from the source to the mouth in the Volga.
20
10
A
0
Zooplankton (g/m 3)
5.0
2.5
B
0
Zoobenthos (g/m 2)
60
40
20
C
0 3000
2000
1000
Distance from mouth (km)
0
37
Chapter | 2 Volga River Basin
P. vejdovsky Hrabe, Baikal amphipods Gmelinoides fasciatus (Kopylov 2001; Pavlov et al. 2003), gammarids Dikerogammarus haemobaphes (Eichw.) (Bakanov 2003), and Chinese crab Eriocheir sinensis Edwards. Macrozoobenthos biomass in the deepwater zone of upper Volga reservoirs depends considerably on the thickness of silt sediments and the current regime. Minimal biomass values (0.1–0.5 g/m2) were found in riverine areas of Rybinsk and Gorky reservoirs, while maximal biomass was found near Rybinsk reservoir dam (Figure 2.6). Average biomass within the sunken Volga River channel and in the reservoirs varies little, from 13.0 1.8 g/m2 (Uglich Reservoir) to 19.4 3.7 g/m2 (Rybinsk Reservoir).
2.6.1.5 Fish Ichthyofauna of the Volga River is represented by 23 families with the most diverse being cyprinids (36 species), percids (9 species) and salmonids (8 species) (Berg 1948, 1949a, 1949b). Prior to regulation, there were up to 69 fish species comprising 5 groups. 1. Species living all along the river such as sterled sturgeon, roach, dace, chub, ide, redeye, zherekh, belica, undermouth, bleak, bystranka, silver bream, bream, white-eye bream, blue bream, sabrefish, sazan, sheatfish, pike, burbot, pikeperch, Volga pikeperch, and perch. 2. Species inhabiting separate sites of the basin or tributaries such as river lamprey, trout, taimen, grayling, and minnow. 3. Species of brackish waters of the delta such as Caspian kilka, stickleback, needle-fish, and some sculpins. 4. Anadromous species such as beluga, sturgeon, stellate sturgeon, ship, Volga and black-backed shad, lamprey, sheefish, and Caspian salmon. Representatives of the group fattened in the Caspian Sea, went upstream in the river to spawn, and then migrated downstream back to the sea with fry. Sturgeons reached the town of Rzhev, blackbacked shad arrived at the Oka and Kama Rivers, and Ponto-caspian alosa (Alosa caspia) arrived at Yaroslavl. 5. Semi-anadromous fish inhabiting the desalinated part of the Caspian Sea and spawn in the delta at a distance of 600 km, including sterled sturgeon, bream, vobla (Rutilus rutilus caspicus), pikeperch, Volga pikeperch, sheatfish, three species of clupeids, kilka, rearl roach, barbel, shemaya and vimba. Regulation of the Volga resulted in the disappearance of a distinctive ichthyofauna in the upper, middle, and lower Volga. Before filling of reservoirs, ichthyofauna of the upper Volga consisted of 38 species of residential fish and 6 species of anadromous fish, that is Caspian lamprey, Russian sturgeon, beluga, stellate sturgeon, sheefish (Caspian migrants), and eel (Baltic migrant). From the source up to the Sheksna confluence, grayling dwelled in the main channel, while trout inhabited some tributaries. Ecological composition of ichthyofauna in the Volga and tributaries did not strongly
differ and consisted of the same reophilous elements typical of the entire catchment (Yakovlev 2000). After filling the reservoirs, Caspian anadromous fish disappeared. At present, grayling, Volga undermouth, and chub form small local populations in tributaries and in the Volga upstream of the town of Tver. Twenty-five mainly limnophilous species can be found in Verkhnevolzhskoe reservoir, although eutrophication resulted in the gradual disappearance of vendace, a valuble coregonid fish (Ivanov & Pechnikov 2004). There is no reliable information on selfreproducing populations of trout. The only residential species of sturgeon in the upper Volga basin, sterled sturgeon, which was among the earlier trade fish can be found as a small self-reproducing population in Gorky reservoir. Relic populations are found in Lake Beloye, and vendace and smelt settle in the upper Volga and along the Volga cascade. Dominating fish species are bream, roach, blue bream, silver bream, sabrefish, perch, and pikeperch, all limnophilous fishes. At present, the annual catch is about 300 tons in Ivankovo reservoir, 200 tons in Uglich reservoir, 1500 tons in Rybinsk reservoir, and 350 tons in Gorky reservoir. Catches consist mainly of bream, roach, blue bream and pikeperch (Kopylov 2001; Ivanov & Pechnikov 2004). Since the 1930s, attempts of acclimation and breeding of a number of species have been undertaken. However, only sazan and peled formed small self-reproducing populations, and the occasional acclimation of Amur sleeper and guppy. Since the 1980s, self-reproducing species of Baltic and White Sea basins (nine-spined stickleback) and euryhaline Ponto-Caspian species (Ponto-Caspian tyulka, southern ninespine stickleback, round goby, Caspian bighead goby, stellate tadpole-goby) are present. Self-reproducing populations are formed also by round goby, kilka and bitterling. Altogether, there are self-reproducing populations of 14 nonnative species in the upper Volga.
2.6.2. Middle Volga 2.6.2.1 Plants The middle Volga lies within forest, forest-steppe and steppe biomes. In the north it lies in the zone of spruce and northern broad-leaf forests, in the zone of herb-feather grass steppe in the south, and within meadow steppe mixed with broad-leaf and pine forests in the center (Isachenko & Lavrenko 1980). After construction of Cheboksary and Kuibyshev reservoirs, virtually no floodplain vegetation was preserved in the middle Volga. The banks of the middle Volga reservoirs are mostly open meadow or meadow-steppe. On the banks of islands in forest-steppe and, especially, in forest zones, osier thickets (Salix triandra, S. viminalis etc.) are found. Aquatic vegetation is rich and diverse (95 associations 43 formations). The greatest area is occupied by narrow-leaved cattail (Typha angustifolia), reed (Phragmites australis), manna grass (Glyceria maxima), bulrush (Scirpus lacustris), pondweed (Potamogeton
38
pectinatus, P. perfoliatus, P. lucens, P. natans), and hornwort (Ceratophyllum demersum). Aquatic flora are represented by 142 species of macrophytes, including 61 genera and 38 families. Most diverse are the pondgrasses (Potamogeton) at 21 species and 14 hybrids. High diversity is found in the flora of damp sandy and rubble shoals in Kuibyshev reservoir, where the boundaries of many southern, western and eastern species overlap. Introduced plants are abundant. The most widely spread are Elodea canadensis and Bidens frondosa.
2.6.2.2 Algae During 1957–1995, the number of phytoplankton taxa in the middle Volga reservoirs (Yakovlev 2000; Trifonova 2003) accounted for 1335 species (1628 species, varieties and forms) and was similar to that in the upper Volga. The greatest phytoplankton diversity was found in Kuibishev reservoir (1166 species). In Cheboksary reservoir, the number of taxa is equal to that in Gorky reservoir located upstream. Algal flora of the middle Volga and especially in Kuibishev reservoir is characterized by a high diversity of euglenoids. The diatom spring bloom is dominated by Stephanodiscus hantzschii, S. minutulus, S. binderanus, Aulacoseira islandica, Asterionella formosa, M. varians, and at times species of the genus Synedra, S. ulna, S. acus. In summer, the complex is replaced by a combination of diatoms, cyanobacteria and green algae. Among them the most typical are the diatoms Aulacoseira granulata, A. ambigua, A. subarctica, Cyclotella meneghiniana, Skeletonema subsalsum, Stephanodiscus invisitatus, S. neoastraea, Fragilaria crotonensis, Diatoma tenuis; cyanobacteria Aphanizomenon flos-aquae, Microcystis aeruginosa, M. wesenbergii, M. pulverea (Wood) Forti emend. Elenk., species of genus Anabaena; chlorophytes Pediastrum, Coelastrum, Chlamydomonas, Oocystis, Scenedesmus, Monoraphidium, Planctococcus, and Pandorina morum. At times, euglenoids (Euglena, Trachelomonas, Phacus) dominate in Cheboksary reservoir in summer. Diatoms form a significant part of the algal community in autumn (Okhapkin 1994; Trifonova 2003). Since the 1980s, cryptomonads (Cryptomonas, Chroomonas) became an important component of the late spring and autumn phytoplankton community (Okhapkin 1994; Pautova & Nomokonova 2001). The invasive diatom species, Actinocyclus normanii began dominating since the 1980s in Kuibishev reservoir in summer and autumn (Genkal et al. 1992). Mean annual phytoplankton biomass during the ice-free period of 1956–1992 increased from 1.6 to 16.3 g/m and reached maximal values in the 1970s in Kuibishev reservoir.
2.6.2.3 Zooplankton Zooplankton of the middle Volga consists of over 200 species of the same large taxa, that is Cladocera, Copepoda, and Rotifera, as the upper Volga. Among them, the
PART | I Rivers of Europe
Rotifera (>50% of total species number) and Cladocera (>30%) prevail. The most abundant are Crustacea. Copepods make up >60% of the total biomass in Cheboksary reservoir, while Cladocera dominate in Kuibyshev reservoir (Shurganova 1987; Timokhina 2000; Shurganova et al. 2005). Widespread and numerous taxa include Crustacea Chydorus sphaericus, Bosmina longirostris, B. longispina, B. coregoni, Daphnia galeata, D. cucullata, Mesocyclops leuckarti, Thermocyclops oithonoides, Cyclops kolensis, C. vicinus, Acanthocyclops vernalis (Fisch.), Heterocope caspia Sars, Eurytemora affinis (Poppe), Eudiaptomus gracilis, Leptodora kindtii, Bythotrephes longimanus, and Rotatifera Brachionus calyciflorus Pallas, B. angularis Gosse, Keratella quadrata (O.F. M€uller), Asplanchna priodonta, Conochilus unicornis. As with the upper Volga, two groups of non-native species can be distinguished. The first group consists of the northern lacustrine forms entering downstream from the upper basin: Heterocope appendiculata, Eudiaptomus gracilis, Cyclops kolensis, Eurytemora lacustris (Poppe), Limnosida frontosa, Daphnia cristata, Bosmina longispina, B. coregoni mixta (=B. coregoni kessleri (Uljanin), Bythotrephes longimanus. At present, most of them are basic components of the middle Volga. Introduction of southern species began before regulation of the Volga. Among them, Heterocope caspia, Eurytemora affinis were found in Kuibyshev reservoir in the 1960s, the last becoming numerous since 1984 (Timokhina 2000). Two southern species entered the middle Volga just recently. The Caspian Cornigerius maeoticus maeoticus (Pengo) appeared in 1993–1994 and formed high abundances in 2000, and a few individuals of another Caspian Crustacen, genus Cercopagis, have been found in 2002–2005 (Dgebuadze & Slyn’ko 2005). Seasonal (May–October) average zooplankton biomass decreases downstream and varies from 0.7–1.2 g/m3 in river reaches to 0.4–0.9 g/m3 in lentic habitats (Shurganova 1987; Timokhina 2000). Long-period zooplankton dynamics show an increase in the amplitude in annual biomass as well as tendency for a decrease overall. Major changes in zooplankton of Kuibyshev reservoir took place since 1982, when the number of Rotifera became much lower, and the number of Cladocera much higher after filling of Cheboksary reservoir.
2.6.2.4 Zoobenthos More than 600 zoobenthic species have been identified from the middle Volga. The richest in number are Chironomidae (200 species) and Mollusca (112 species). At present, oligochaetes, chironomides and mollusks make up the most in zoobenthic number and biomass. The Ponto-Caspian gammarides Dikerogammarus haemobaphes (Eichw.), Pontogammarus obesus (G. Sars) and P. robustoides (Grimm) also are abundant (Butorin & Mordukhai-Boltovskoy 1979;
39
Chapter | 2 Volga River Basin
Borodich & Lyakhov 1983; Bakanov 1988, 2005; Zinchenko 2002). The two mollusk species under danger of extinction, Anisus vorticulus and Unio crasus, inhabit the middle Volga. The non-native Ponto-Caspian mollusk Dreissena polymorpha, as well as amphipods Dikerogammarus haemobaphes, P. obesus, P. sarsi (Sowin.), Stenogammarus dzjubani (M.Bolt. & Ljach.) and Corophium curvispinum G. Sars that are common today had been found in the basin before the Cheboksary and Kuibyshev reservoirs were filled. Following impoundment, some intentional introductions had taken place, including the Ponto-Caspian species of polychaetes Hypania invalida, and Manayunkia sp., mollusks Monodacna colorata (Eichw.), Dreissena bugensis, Lithoglyphus naticoides, Teodoxus pallasi Lind., and Borysthenia naticina (Menke), amphipods Corophium sowinskyi Martyn., Paramysis ullskyi Czern., P. intermedia (Czern.), Schizorinchus bilamellatus (G. Sars), Gammarus pulex (L.), Dikerogammarus caspius (Pallas) and Pterocuma sowinskyi (G. Sars), and leeches Archaeobdella esmonti Grimm (Butorin & Mordukhai-Boltovskoy 1979; Pirogov et al. 1990; Antonov 1993; Bakanov 2005; Dgebuadze & Slyn’ko 2005). In 2001, two Baikal gammarides Gmelinoides fasciatus and Micruropus possolskyi Sow. (Bakanov 2005) were intentionally introduced into Gorky reservoir (Yoffe 1968) as well as the Chinese crab Eriocheir sinensis and amphipoda Pontogammarus crassus Grimm, Corophium fluviatilis (Martynov) in Cheboksary reservoir. Initially after the Kuibyshev reservoir was in operation, average macrozoobenthos biomass in the channel was low at about 5 g/m2 (Butorin & Mordukhai-Boltovskoy 1979; Borodich & Lyakhov 1983). In 1985, average macrozoobenthos biomass within the Volga River and in Kuibyshev reservoir was 12.1 2.3 g/m2, and 5.6 2.1 g/m2 in Cheboksary reservoir, mainly oligochaetes (Bakanov 1988). As the Cheboksary reservoir bottom became siltier, macrozoobenthos biomass within the channel increased and in 2001 was 9.7 2.1 g/m2.
2.6.2.5 Fish There are 19 fish species in Cheboksary reservoir and only 11 (vendace, smelt, guppy, nine-spined stickleback, Amur sleeper, stellate tadpole-goby, monkey goby, Caspian bighead goby, round goby, tubenose goby) have self-reproducing populations. Most non-native species first appeared from 1950–1960, including five salmonids and four cyprinids, while six percids appeared in the mid-1990s. Cyprinid species were observed at a single time in the reservoir, and among salmonids only vendace and smelt formed self-reproducing stocks. Percids, in general, can be found everywhere. The single representative clupeid, the tyulka, is highly abundant (Dgebuadze & Slyn’ko 2005). Before filling the Kuibyshev reservoir, 47 fish species inhabited this reach of the Volga. After the reservoir had been filled in 1956, the number of species increased
(Dgebuadze & Slyn’ko 2005), most of them represented by typical limnophilous cyprinids and percids. Self-reproducing fish include two species of silver carp, Asian carp, peled, buffalo, some occasional mysids (i.e. Ponto-Caspian needle-fish, round goby, stellate tadpole-goby), non-native fish from the north (i.e. vendace, European smelt), and some fishes from the south (i.e. Ponto-Caspian tyulka). Altogether, 9 species are self-reproducing and 12 species belong to occasional non-native ichthyofauna. Species such as round goby, Amur sleeper and pipefish reproduce successfully and shown increases in number. More recently, grayling and common undermouth have been found, and paddlefish and channel catfish are self-reproducing. Amur bitterling, Siberian loach and guppy have been found but their distribution is still unknown, and individuals of Siberian sturgeon and bester (beluga sterled) also may be encountered. Few invasive species have self-reproducing populations in the middle Volga, and they are mostly insignificant in number. More valuable fish introduced by direct efforts are rare and do not have self-reproducing populations. The basic fishery consists of limnophilous species, mainly cyprinids and percids that are typical of the present Volga. Presently, the annual catch is about 2000 tons in Kuibyshev reservoir and 200 tons in Cheboksary reservoir, consisting mainly of bream, roach, silver bream, and blue bream (Ivanov & Pechnikov 2004).
2.6.3. Lower Volga 2.6.3.1 Plants The lower Volga flows through herb-feather grass, fescuefeather grass and deserted wormwood-fescue-feather grass steppes (Lipatova 1980). Remnants of floodplain vegetation in the lower Volga are preserved on islands in Saratov and Volgograd reservoirs and within the Volga-Akhtyubinsk floodplain, being represented by osiers (Salix acutifolia, S. triandra, S. viminalis), white willow (S. alba), black poplar (Populus nigra), elm (Ulmus laevis) and oak (Quercus robur) forests, fescue (Festuca valesiaca) and herb-fescue steppes, and coach grass (Elytrigia repens) and herb-coach grass halophyte meadows turning into sedge and boggy meadows of Carex acuta, Sparganium erectum, Alisma plantago-aquatica, and Butomus umbellatus in depressions (Lipatova 1980). Aquatic vegetation is less diverse than in the upper and middle Volga. Here the main vegetation in shallows is semi-submersed species dominated by reed Phragmites australis and narrow-leaved cattail Typha angustifolia. Submersed plants are dominated by pondweed Potamogeton perfoliatus. In lower reaches of the river, Phragmites australis is replaced by P. altissimus, developing sprouts 4–6 m high. On the whole, the aquatic flora in the lower Volga is represented by 135 species of vascular plants.
40
2.6.3.2 Algae From 1968–2002, 1003 species (1179 species, varieties and forms) of phytoplankton had been recorded in the lower Volga reservoirs (Yakovlev 2000; Trifonova 2003). Phytoplankton of Saratov reservoir is the most diverse. Diatoms and green algae are the richest in terms of species diversity in the lower Volga, although the number of taxa is lower (1179) than found in the upper and middle Volga. Diatoms and cyanobacteria are the most important members of the lower Volga phytoplankton community. Diatoms Stephanodiscus hantzschii, S. binderanus, Aulacoseira islandica, Asterionella formosa, Diatoma tenuis, Melosira varians, and Skeletonema subsalsum are most often dominant in spring. In summer, diatoms S. subsalsum, A. granulata and cyanobacteria Aphanizomenon flos-aquae, Microcystis aeruginosa, M. wesenbergii, M. pulverea and species of genus Anabaena form an important part of the phytoplankton community. Chlorophytes (species of genus Pediastrum, Scenedesmus, Monoraphidium, Coelastrum, Actinastrum, Chlamydomonas and Pandorina morum) are also abundant at this time (Gerasimova 1996; Daletchina & Silnikova 2001; Pautova & Nomokonova 2001; Poptchenko 2001; Trifonova 2003). The invasive diatom Actinocyclus normanii became a significant component of the summer-fall phytoplankton in the lower Volga since 1980. From 1980 to 1990, the proportion of non-heterocystous cyanobacteria of genus Oscillatoria, Phormidium, Lyngbya, Aphanothece, and Synechocystis increased. In the 1990s, cryptomonads became an important part of the phytoplankton community. Spring and summer complexes of algae continue to develop in autumn. The number of algae taxa in the unregulated section of the lower Volga is even less than in the Saratov and Volgograd reservoirs. In 1964–1969, richness totalled only 287 species, varieties and forms (Voloshko 1971), increasing to 390 in 1984–1991 (Labunskaya 1995). According to Labunskaya (1995) and our unpublished data (1989–1991), diatoms dominate during the ice-free period. The spring complex consists of Stephanodiscus hantzschii and Aulacoseira islandica, while in summer it includes A. granulata, Skeletonema subsalsum, Actinocyclus normanii and blue-green algae Aphanizomenon flos-aquae and Microcystis aeruginosa. In 1997, 127 taxa of algae were found in this reach of the Volga. Together with the common diatoms and cyanobacteria, Oscillatoria (cyanobacteria) and Chroomonas (cryptomonads) were recorded as dominants (Trifonova 2003). Average annual phytoplankton biomass during the icefree period of 1984 to 1990 ranged from 0.6 to 7.6 g/m3 with maximal values in 1989 (Labunskaya 1995). In general, the species diversity of phytoplankton decreases from the upper to lower Volga. In recent years, the proportions of invasive brackish-water diatoms, non-heterocystous cyanobacteria and mixotrophic cryptomonads have increased in the Volga. Average annual phytoplankton biomass during the ice-free period of 1968 to 1993 increased from 0.7 to 14.5 g/m3 and
PART | I Rivers of Europe
reached maximal values in the 1970s in Volgograd reservoir. In Saratov reservoir, maximal biomass of phytoplankton reached 12.6 g/m3 in 1988 and 1989.
2.6.3.3 Zooplankton As well as in the other basins, the zooplankton community in the lower Volga consists of Cladocera, Copepoda, and Rotifera. There are more than 200 species found with a prevalence of Rotifera (>50% of the total) and Cladocera (>30%). The crustaceans Copepoda and Cladocera make up from 50% to 90% of the total biomass. The usual species among them are Daphnia galeata, Chydorus sphaericus, Bosmina longirostris, Mesocyclops leuckarti, Thermocyclops oithonoides, Cyclops kolensis, C. strenuus Fisch., Acanthocyclops vernalis, Heterocope caspia, Eurytemora affinis, Leptodora kindtii), Cornigerius maeoticus maeoticus. The prevalent Rotifera species are Keratella quadrata, Asplanchna priodonta, Synchaeta pectinata Ehrenb., Brachionus quadridentatus Herm., and Euchlanis triquetra Ehrenb. Like in the other two basins, two groups of non-native species can be distinguished. The first is formed by the northern lacustrine forms entering downstream from the upper Volga, including Heterocope appendiculata, Eudiaptomus gracilis, Cyclops kolensis, Eurytemora lacustris, Limnosida frontosa, Daphnia cristata, Bosmina longispina, B. coregoni kessleri, B. obtusirostris Sars, B. crassicornis P. E. M€uller, Bythotrephes longimanus. At present, species such as Cyclops kolensis and Bosmina longispina are the main planktonic taxa in the lower Volga. The second group consists of the southern Caspian species, and most of them began their invasion into the region after construction of the reservoirs. Among them, Calanipeda aquaedulcis Kritsch colonized first in the early 1970s in Volgograd reservoir and later, in 1982, it was found in Saratov reservoir. Cornigerius maeoticus maeoticus became numerous in Volgograd reservoir since 1970 and in 1996 it appeared in Saratov reservoir (Mordukhai-Boltovskoy & Dzuban 1976; Dgebuadze & Slyn’ko 2005). The non-native Cercopagis sp. had high abundances in the lower part of Volgograd reservoir in 2002 (Malinina et al. 2005), although Heterocope caspia had colonized the lower Volga even earlier before reservoir filling. Seasonal development in zooplankton is characterized with a summer peak. Zooplankton biomass is low, being on average 500 taxa, and among them the Chironomidae (200 species) and mollusks (112 species) are the most diverse (Nechvalenko 1976; Butorin & Mordukhai-Boltovskoy 1979; Zinchenko 2002). The highest quantity and biomass is found in the same oligochaete, chironomid, and mollusk species as the ones dominating in the upper and middle Volga. Additionally, the Ponto-Caspian gammarids Dikerogammarus haemobaphes and Pontogammarus obesus are common (Nechvalenko 1976; Butorin & MordukhaiBoltovskoy 1979). Four inhabitants of the lower Volga benthic fauna are in danger of extinction: Odonata (Coenagrion ornatum Selys. and Leucorrhinia pectoralis) and mollusks (Anisus vorticulus and Unio crasus). At present, macrozoobenthos of the lower Volga contains a number of non-native species, among them include the Ponto-Caspian crustaceans Dikerogammarus haemobaphes, Pontogammarus abbreviatus (G. Sars), P. crassus, P. obesus, P. sarsi, Stenogammarus compressus (G. Sars), S. macrurus (G. Sars), Chaetogammarus ishnus (Stebb.), Pandorites platycheire (G. Sars), Corophium curvispinum G. Sars, Paramysis baeri (Czern.), P. ullskyi, P. intermedia, P. lacustris (Czern.) and Limnomisis benedeni Czern., polychaetes Hypania invalida, mollusks Monodacna colorata, Dreissena polymorpha, D. bugensis, Lithoglyphus naticoides, and Teodoxus pallasi, leeches Archaeobdella esmonti, and Chinese crab E. sinensis (Antonov 1993; Bakanov 1993; Nechvalenko 1976; Butorin & Mordukhai-Boltovskoy 1979; Dgebuadze & Slyn’ko 2005). Today, 15 Ponto-Caspian crustacean species are found in the lower Volga macrozoobenthos and 14 in the middle Volga macrozoobenthos, while only Dikerogammarus haemobaphes is found in the upper Volga. Due to higher current velocities, macrozoobenthos biomass in the main channel has not changed since reservoir construction and averages about 3 g/m2. During the first years after the Volgograd reservoir, macrozoobenthos biomass did not differ from that of Saratov reservoir. However, by 1985 it had increased by more than three times and reached 10.5 3.5 g/m2. Crustaceans, polychaetes and oligochaetes dominate the biomass here (Butorin & MordukhaiBoltovskoy 1979; Bakanov 1988).
sabrefish, sazan, crucian carp, tench, sheatfish, pike, burbot, pikeperch, Volga pikeperch, perch, and ruffe became common and dominate the fishery (Reshetnikov 1998). A total of 17 new species have appeared in the lower Volga. Non-native fishes in Saratov reservoir suggest that the species have a different origin (Dgebuadze & Slyn’ko 2005). Peled, vendace, smelt came in 1960 downstream from the upper basins. Species such as Amur sleeper, Caspian bighead goby, tubenose goby, stellate tadpole-goby, pipefish, and southern ninespine stickleback formed self-reproducing populations. As a result of direct introduction, Asian carp, white and spotted silver carp, smallmouth and black buffalo, and Siberian sturgeon appeared in the reservoir mainly during the 1980s. However, the introductions were not successful because of the small number of fish introduced, and none have been found in the fishery catch in recent times. New fishes appeared in the Volgograd reservoir since 1969, within 10 years after filling (Dgebuadze & Slyn’ko 2005), including the European vendace, smelt, and peled among them. However, only vimba, Amur sleeper, Caspian bighead goby, tubenose goby, stellate tadpole-goby, pipefish, and the southern ninespine stickleback that appeared in late 1990s have self-reproducing populations. A number of valuable species appeared as a result of direct introduction from 1967 to 1990, including white and spotted silver carp and Asian carp smallmouth and black buffalo, black carp, and vimba. These non-native fishes have little significance in the commercial fishery, making about 1% of the total catch. The small-sized Amur sleeper and sculpins are caught by fishermen. Today, the annual catch is about 700 tons in Saratov reservoir, and 1000 tons in Volgograd reservoir, consisting mainly of bream, roach, silver bream, and perch (Ivanov & Pechnikov 2004). The lower Volga had great fishery importance before building of the dam near Volgograd, with an annual output over 12 000 tons. At present, there is no commercial fishery in the lower basin. Regulation of the Volga resulted in the disappearance of a distinctive ichthyofauna in the upper, middle, and lower Volga. The fish population now consists mainly of typical limnophilous species that differ little along the river because of the invasion of non-native species. These species enter as a result of direct introduction of valuable fish as well as the occasional expansion and accidental intrusion. Non-native species originated from three faunistic groups, that is Ponto-Caspian, Arctic, and Chineselowland (plain) group, and the most significant being the Ponto-Caspian complex.
2.6.3.5 Fish
2.7. MANAGEMENT AND CONSERVATION
At present, ichthyofauna of the lower Volga consists of 62 species. After filling of Volgograd reservoir, anadromous fish as well as a number of rheophilous species at sites above the dam disappeared. Limnophilous fish such as roach, ide, bleak, silver bream, bream, white-eye bream, blue bream,
2.7.1. Economic Importance The geographic situation of the Volga and its large tributaries allowed for the development of trade relations between West-European countries and pre-Caspian countries of
42
middle Asia by the 8th century. Russia was originally founded along the Volga, partly by Viking entrepreneurs using it as a road to the south from an entry point near Archangel. From the earliest times, the Volga was a great trade way. Cloth, metal fabrics, and precious stones were transported from Central Asia to the north. Furs, wax, honey and slaves were moved from Slavic and Bulgarian lands to Caspian countries. Trade declined in the 11th century following the fall of the Khazar Khaganate, and the Tatar invasion virtually eliminated economic activity in the middle and lower Volga regions since the 13th century. During this period, the river routes from northeast Russia to Veliki Novgorod played an important role in barter exchange with Europe. It has been only since the 14th century that trade has revived throughout the entire Volga with large market centres appearing along the Volga following liberation from Tatar control. The main tradeways moved to the west in the 18th century. Transportation increased into the Volga’s northern tributaries (rivers Tvertsa, Mologa, Sheksna), and their upper reaches were connected with rivers of the Baltic system by a network of man-made canals. Inland water transport was completed on the Volga by the middle of the 19th century. Today, the Volga is connected with the Baltic Sea by the Volga-Baltic water way, Vyshniy Volochek and Tikhvin systems, with the White Sea via the Northern Dvina system and the White Sea-Baltic Canal, and with the Sea of Azov and the Black Sea through the Volga-Don Canal. The construction of reservoirs resulted in an increase of guaranteed depth up to 4 m along the whole length of the river that, in turn, boosted freight turnover from 27.4 million tons in 1930 to 300 million tons in 1990. Some large reservoirs also included hydroelectric power stations in the 1930s with a current gross output of 11 098 thousand kilowatts and total energy generation of 3968 billion kilowatt-hours. The Volga catchment occupies more than a third of the European area of Russia and 8% of the total area of Russia. At present, it is the most populated region in the Russian Federation and 39 administrative units with a total population of some 60 million (40% of the country’s population) are located here. Around 45% of industrial and 40% of agricultural products are produced here. A total 426 of 1057 Russian cities, including 7 cities with a population of more than 1 million people and 10 with populations from 500 000 to 1 million, are situated in the region. The Volga and its tributaries account for 70% of the goods carried by river transport in Russia. More than half of all fish and 90% of all sturgeons from inland waterbodies are caught in the Volga catchment (Avakyan 1998). Vast woodlands are typical for the upper Volga basin. Large areas of the middle and some of the lower Volga basin are occupied by grain and technical crops, and melon farms and private garden plots are common. There are oil and gas fields in the Volga-Urals region, and major deposits of potassium salts are found
PART | I Rivers of Europe
near the city of Solikamsk. Table salt is mined in the lower Volga basin around lakes Baskunchak and Elton.
2.7.2. Conservation and Restoration In the Volga basin, the protected territories, i.e., preserves, forest reserves, national parks, recreational zones, etc., make an appreciable part of the catchment area (Table 2.1). A network of nature reserves covering more than 6000 km2 reside in the Volga catchment. Principal information on reserve activity, and their flora and fauna is summarized in: Sokolov and Syroechkovsky (1988, 1989), Sokolov (1988), Internet sites ‘Reserves’ (http://www.water.zapovednik.com/), ‘Reserves of Russia’ (http://www.sevin.ru/natreserves). The Darwin State Wildlife Biosphere Reserve, established in 1945 and included in the international network of biosphere reserves, is situated in the upper Volga basin within the territory of Vologda and Yaroslavl provinces. The reserve covers an area of 1400 km2 of which 450 km2 is occupied by Rybinsk reservoir. Around 19 species of fish, 7 species of amphibians, 5 species of reptiles, 194 species of birds, 37 species of mammals, 600 species of higher plants 37 of which are rare species, 70 species of mosses, >60 species of lichens, and 123 species of pileate fungi are found in the reserve. The area has a high abundance of brown bear Ursus arctos L., and until recently there was a wood grouse (Tetrao urogallus L.) farm. The Kerzhenskiy Reserve, 469 km2, was organized in 1993 in Nizhniy Novgorod province. It lies in the Kerzhenets River basin (the Volga’s left tributary) within the middle Volga. The reserve is included in the UNESCO network of biosphere reserves under the name ‘Nizhegorodskoye Zavolzhie’. Natural areas of southern taiga were restored in its territory. The Zhiguli State Wildlife Reserve established in 1996 in Samara province is situated in the middle Volga. It covers an area of 230 km2 of which 176 hectares is occupied by Volga waters. About 800 species of higher plants, 20 species of mosses, 20 species of lichens, and 30 species of pileate fungi are found in the reserve. About 240 species of vertebrates including 52 species of mammals, 155 bird species, 6 species of reptiles, 5 species of amphibians, and 19 fish species inhabit its territory. The Astrakhan State Wildlife Biosphere Reserve was founded in the Volga delta in 1919. Presently it occupies 680 km2, including 110 km2 of the Caspian Sea. These open-water areas and marshlands are of international importance (Ramsar Convention – the Volga Delta) and included in the international network of biosphere reserves. Approximately 300 species of higher plants are found here. Thirty species of mammals, 230 bird species and 50 fish species inhabit the area, and the Caspian Ornithological Station operates in the reserve. Measures are taken at each reserve to culture and preserve particularly valuable species of flora and fauna. The
43
Chapter | 2 Volga River Basin
following plants of the Volga basin are included in the Red Book of Russia: (Cypripedium macranthon Sw., Cypripedium calceolus L., Cephalanthera rubra (L.) Rich., Koeleria sclerophylla P. Smirn., Schivereckia podolica (Bess). Andrz. ex DC, Globularia punctata Lapeyr., Trapa natans L., Nelumbo nucifera Gaertn. [incl. N. caspicum (DC) +Fisch., N. komarovii Grossh.]), mammalia (e.g. muskrat Desmana moschata L., European bison Bison bonasus bonasus L.), and birds (e.g. white well sweep Grus leucogeranus Pallas, golden eagle Aquilla chrysaetos L., buff-backed heron Bubulcus ibis (L.) Wagler, spoonbill Platalea leucordia L., bushy pelican Pelecanus Pelecanus Brush, bald eagle Haliaetus albicilla (L.), pinc pelican Pelecanus onocrotalus L., osprey Pandion haliaetus (L.), falcon Falco cherrug Gray, little bustard Tetrax tetrax L., flamingo Phoenicopterus roseus Pallas, black stork Cyconia nigra L., and hawk Circaetus gallicus Gmelin) (http://www.biodat.ru).
problems concerning environmental safety from industrial production and the formation of sustainable economic developments (Komarov 1997). Priority guidelines for major ecologically poor complexes include: Development of master non-waste technologies for re-equipment and reconstruction of ecologically unsound developments in the region; development of environmentally safe production of chemicals as well as process technologies that together ensure an increase in ecological-sound industry; realization of new technologies in industry; development of ecologically sound agriculture; rehabilitation of forests and prevention of their degradation, wildlife conservation, and development of wildlife reserves; creation of favourable conditions for development of the fishery; reclamation and use of industrial and municipal wastes; organization of environment monitoring systems and development of a geo-information system; improvement of ecological conditions in cities; and development of ecological education and professional training.
2.8. CONCLUSIONS AND PERSPECTIVES Transformations of the Volga have caused major changes in water circulation that affected the energy flow and massexchange such as water balance and exchange, variation in water levels, flow velocity, and thermal regime. The morphology of reservoirs is influenced by natural climatic factors (i.e. water quantity and quality) as well as human activities that regulate flow. Reservoirs represent unstable ecosystems; however they are integral parts of the Volga River. Together with positive aspects regarding economic development, the Volga transformation has had serious consequences such as flooding of productive lands, collapse of banks due to fluctuations in water level, and losses in the fishery. At present, a fish community resembling the one before regulation inhabits only two reaches of the river. Such rheophilous species such as dace, chub, undermouth, zherekh, loach, gudgeon, minnow, bystranka prevail in the headwaters of the Volga and all typical river fishes can be found within the reach from the river mouth to Volgograd dam. However, their numbers decrease upstream because of unfavorable changes in hydrological regime after regulation. Among the sturgeons, belugas are now rare and sheefish (Caspian salmon) are essentially extinct. Regulation of the Volga resulted in the disappearance of a distinctive ichthyofauna in the upper, middle, and lower Volga. The fish population consists mainly of the same typical limnophilous species along the river because of the invasion of non-native fishes. The high density of humans and extensive industrial development caused a strong anthropogenic impact on the river and its biota. Consequently, conservation actions and nature management should emphasize preservation and recovery of the Volga catchment. The realization of a special federal program ‘Revival of the Volga’ can help in this situation. This program aims at solving urgent
2.9. MAJOR TRIBUTARIES OF THE VOLGA RIVER 2.9.1. The River Kama 2.9.1.1 Introduction The Kama is the largest tributary of the Volga. Its name comes from the Udmurt ‘kam’, meaning ‘river’ or ‘current’. The Kama-Vyatka area was originally colonized by Fins before the end of the 11th century. The first Russian boats arrived on the Kama during this period and resulted in various Russian settlements. The river was a major link of communication between Asia and Europe. For instance, Yermak the Cossack ataman travelled to Siberia on the Kama in the mid-16th century, thereby connecting Siberia with Muscovite Russia. The natural riches of the Ural region caused intensive development of the Kama catchment. The Kama is the 5th longest river in Europe after the Volga, Danube, Ural and Dnieper (Shmidt 1928b).
2.9.1.2 Paleography The Kama valley is older than the Volga, being present already in the early Quaternary (Shklyaev 1964). The Kama and its major tributary Vishera flowed to the Caspian Sea, but presently flow in the upper basin drains to the north. Later glaciation reformed its hydrographic network. The geology as well as the relief of the catchment is diverse. The Ural highlands are situated between the Russian plain in the west and the Siberian plain in the east. The Russian plain and Ural Mountains are divided by an elongate pre-Ural marginal depression that forms the Yuryuzan-Slyvinskaya plain and Belskaya depression. The present-day Urals were formed by neogenic and quaternary vertical-block movements of
44
ancient folded-fault massifs, erosive activity of rivers, and long-term weathering. Sedimentary rocks (sand, clay, sandstone, conglomerate, limestone, shale) make up much of the geology in the catchment. Rocks differing in age and composition stretch longitudinally in the catchment. The Eastern European plain is composed of mainly horizontal-beds of sedimentary rocks of Precambrian granite-gneiss of the Russian plain. The most widely distributed are deposits from the Upper Permian period. Among them, Tatar deposits (in the western and central parts of the region) are represented by multi-coloured clays and marls often alternating with limestone and sandstone bands. In the upper Kama and Vyatka basins, beds of Jurassic and Lower Cretaceous marls, clays and sands are superimposed on these deposits. In the Uval area of the Vyatsky basin, limestone and gypsum of the Kazan layer are interspersed among multi-coloured marls. Near the Kama river valley, Tatar deposits are replaced by Kazan deposits in which limestone and marl bands occur among red-coloured clays and sandstones. To the east on the left bank of the middle Kama and along the lower river Belaya, lower Permian Ufa deposits with bands of gypsum occur. Along the margins of the Russian plain are highly soluble lower Permian rocks causing extensive karstic formations. The pre-Ural depression is filled by weakly dislocated Permian sedimentary rocks including some typical salt-bearing sections near the city of Solikamsk, and deposits of gypsum and anhydrites. In the plain, Paleozoic rocks are mostly covered by thin Quaternary deposits of mainly loam soils, and clays and sands in some areas. In the northern Kama catchment, fluvio-glacial sands are underlain by clays. In tributary valleys of the Chusovaya, Sylva and Iren, karstic areas develop under river deposits and non-karstic and karstic rocks of carbonate, sulphate and halogenous composition alternate.
2.9.1.3 Physiography, Climate, and Land Use The relief of the catchment is distinguished by the Ural Mountains in the middle, north and south; and the Eastern European plain (along with the pre-Urals) to the east. Coniferous forests similar to Siberian taiga occur in the upper catchment and deciduous forests are found in the lower catchment, both in the forest-steppe and forest biomes. However, large areas of the catchment have been deforested and are used for agriculture or mining. The Ural Mountains are of moderate height (400– 600 m asl) and have a weathered but strongly irregular surface. Some peaks in the south and north can reach 1500– 1600 m asl. In the northern Urals, a system of parallel, gradually decreasing ridges are found to the west along with various forested plateaus at 400–500 m asl. The middle Urals (59 150 to 55 N) reach 500–600 m asl and consist of a rugged hilly plain with single irregularly spaced peaks, the highest being Sredniy Baseg at 994 m asl. Western foothills of the middle Urals are represented by low ranges rising
PART | I Rivers of Europe
within the plain, including among others Basegi (993 m asl), Belyi Spoi (568 m asl), Kirgishansky uval (555 m asl), and Bardymsky (681 m asl). The southern Urals (55 300 to 56 N) are highly mountainous and contain some of the highest ridges, most of these found in the Belaya river basin. The southern Urals extend for 150–200 km in width and include the Uraltau Divide, a wall-like range reaching up to 1000 m asl. The Eastern European plain has an undulating relief of elevated rugged inter-fluvial areas and wide gentle-terraced river valleys. In the upper Kama and Vyatka lies the flat upper Kama upland about 300 m asl and deeply incised by rivers. The middle Vyatka flows south-east through the distinctive Vyatskiy Uval, running north-south at 250– 280 m asl. In the southern pre-Urals, the Bugulma-Belebeevskaya peak rises up to 450–480 m asl and is connected to the west with Obshchiy Syrt. Climate of the region is defined as continental with large variations in annual and daily temperature. Humid air masses from the Atlantic Ocean exert a strong influence on climate. Features of the relief cause the presence of latitudinal zones in climate in the plain and vertical climate zones in the mountains. Severe snowy winters and short cool summers in the north and frosty winters with little snow and comparatively hot summers in the far south characterize the general climatic differences with latitude. In winter, a Siberian anticyclone causes stable but frosty weather with more snow in the pre-Urals and on mountain slopes. Frequent cold-air surges from the north and southern cyclones often bring sharp changes in weather. In summer, the area is influenced by low-pressure air masses from the Barents and Kara seas, while the air masses from the Azores bring hot dry weather. Average annual air temperature in lowland areas of the Kama vary from 0 to 3 C north to south. The coldest month is January, ranging from 17 to 14 C south to east. Lowest air temperatures occur between December and February, reaching 48 . Average daily temperatures 5 C usually occur by the third week in March, and >0 C in the first week in June. The hottest month is July, averaging 16–17 C in the north and about 19 C in the south. Temperatures decrease to around 5 C in late September early October. Winter thaws are rare and short, often lasting for only several hours. Annual precipitation varies widely but decreases north to south. In the north, annual precipitation reaches 1300– 1600 mm. In mountain valleys, annual precipitation is about 850–950 mm. Annual precipitation is 800–900 mm in the northern middle Urals and 600–700 mm in the south. Annual precipitation is 1200–1500 mm in the southern Urals and 500–600 mm in the pre-Urals plain. Precipitation during the year occurs unevenly and is 1.4–1.7 times higher in summer than in winter. Heavy showers are frequent in the middle Urals and pre-Urals, but drought can occur in the south. Snow cover can happen by September and is complete by late October early November. Spring thaw begins in mid-April in the south and late April in the north. In the mountains and in
45
Chapter | 2 Volga River Basin
the northern foothills, spring thaw begins in May. In winter, southerly and southwesterly winds prevail. Wind direction is variable in summer, although northerly, northwesterly and westerly winds are most common. In the mountains, wind direction is affected by orography and mountain-valley winds are common. Annual average wind velocity can vary 2–5 m/s.
2.9.1.4 Geomorphology, Hydrology, and Biogeochemistry The Kama begins in the Ural Mountains, flows east in Udmurtia then south-west in Perm porvince before flowing again through Udmurtia into Tatarstan where it meets the Volga. The Kama flows into the Kuibyshev reservoir in the middle Volga. The length of the river is about 1800 km and its catchment area is about 517 000 km2. Before construction of the Kama reservoir system, its length was 2030 km (Butorin & Mordukhai-Boltovskoy 1979). The Kama main channel forms a large arch with only 445 km separating the river source and its mouth (Shmidt 1928a, 1928b). Around 74 000 rivers and streams totaling 252 000 km in length are found in the Kama catchment. Shallow streams 4 C occurs between October 7 and October 29 and the average date of ice cover occurs between November 2 and November 23. The duration of the ice-cover period lasts from 125 to 171 days. 2.9.1.4.2 Current All the types of currents known for artificial water bodies can occur in reservoirs of the Kama. Discharge currents and wind-drift currents are the most frequent (Devyatkova & Trutnev 1983). Discharge currents occur throughout the year, whereas wind-drift currents are observed only during the icefree period. Discharge currents are most typical in the upper basin, while wind effects and long waves caused by the irregular discharge regime of hydroelectric power stations are common near dams. Inputs of the Kama and Vishera rivers as well as reservoir levels influence flow velocity in the upper Kamskoye reservoir. High velocity currents that occur during the spring
46
flood in the upper reservoir range from 120 to 188 cm/s and are similar to those in the upstream river. Current velocity slows to 40–100 cm/s by the end of June and to 10–40 cm/s in late summer early autumn. However, velocity can increase to 60–100 cm/s during floods from rain. Two-ply currents often develop in the middle lake-like part of reservoir. Flow direction and velocity in the upper layer depends upon wind velocity and direction and rarely exceeds 16–18 cm/s. At the same time, currents in deeper layers are relatively stable. Near the dam, discharge currents vary from 45–50 cm/s in spring to 10–15 cm/s in summer and autumn. In Votkinskoye reservoir, flow velocity also decreases downstream. In spring, velocity is about 1 m/s in the upper reservoir, 0.2–0.5 cm/s in the middle part of the reservoir, and 0.1–0.15 cm/s in the lower reservoir. Velocities are 2–3 times lower in summer. In the lower Kama below the town of Chistopol’ in the Volzhsko-Kamsky reach of Kuybushev reservoir, discharge velocity depends on the reservoir level but typically decrease downstream from 15–30 to 60%) from May to June and Crustacea from July to
48
September. The most abundant are Chydorus sphaericus, Bosmina longirostris, B. obtusirostris, Daphnia longispina O.F. M€ uller, D. cucullata, Mesocyclops leuckarti, Eudiaptomus gracilis, Eurytemora velox Lill., Cyclops vicinus, C. strenuus, Heterocope appendiculata, Leptodora kindtii, Bythotrephes longimanus. Rotifera such as Euchlanis dilatata Ehrenb., Asplanchna priodonta, Polyarthra major Bruck., Synchaeta sp. and Keratella species are also common. After regulation, Crustacea became abundant not only in near-shore areas but also in the main river channel. Mean zooplankton biomass between May and October varies from 1.0 to 4.6 g/m3 (Kortunova 1985, Dementieva 1985). The abundance of zooplankton can reach up to 2.7 million/m3 and 25.5 g/m3 in July in shallow areas in the upper and middle reaches of the river. Long-term records in Sylva bay of Kamskoe reservoir showed increases in zooplankton biomass from 1.4 g/m3 in 1957 to 2.3 g/m3 in 1978. 2.9.1.5.4 Zoobenthos Before regulation, zoobenthos in the Kama was similar to that in the Volga and Oka Rivers. The first information on zoobenthos for the entire Kama under natural conditions and without any anthropogenic impact such as hydropower stations was in 1925 (Behning 1928). Later, 296 taxa were recorded (Tauson 1947): among them Spongia with 1 species, Coelenterata 1, Nematoda 67, Oligochaeta 25, Hirudinea 6, Mollusca 20, Ostracoda 15, Isopoda 1, Amphipoda 6, Mysidacea 1, Decapoda 1, Plecoptera 4, Ephemeroptera 28, Trichoptera 17, Hemiptera 2, Odonata 1, Hydracarina 10, Bryozoa 1, and Diptera 89 including 84 species of Chironomidae. The most frequent chironomids were Chironomus f.l. semireductus, Beckidia zabolozkyi Goetgh. Tanytarsus gr. gregarius, Polypedilum gr. nubeculosum, Procladius, and Ablabesmyia spp. (Gromov 1951). Nematods were the next most speciose, including the widespread species Dorylaimus stagnalis Dujar., D. chrysodorus Bast., Ironus tenuicaudatus de Man., and Plectus cirratus Bast, and were especially numerous in tributary mouths. The most common oligochaetes in the middle Kama included Nais behningi Mich., Propappus volki (Mich.), T. newaensis Mich., and Limnodrilus hoffmeisteri Clap. (Svetlov 1936). Before regulation, Caspian crustaceans, that is Amphipoda, inhabited the middle and lower reaches of the Kama (Behning 1928; Gromov 1954). D. haemobaphes Eich. and the highly abundant Corophium curvispinum Sars inhabited pebble substrates, while other species, for example Stenogammarus macrurus Sars and P. sarsi Sowin., inhabited sandy and sand-pebble areas. Numerous colonies of Metamysis strauchi (Czern.) (Mysidacea) were found in pure sand habitats. The Caspian mollusc D. polymorpha (Pallas) was quite abundant in the lower Kama, especially in stone and pebble habitats (Behning 1928), and later, in 1939, it also occurred in the middle Kama (Gromov 1951).
PART | I Rivers of Europe
Presently, macroinvertebrates in the Kama consist of 250 species and among them Chironomidae make up 50%. Three taxonomic groups, that is Oligochaeta, Mollusca, and Chironomidae, comprise the most zoobenthos in terms of number and biomass. The most numerous are Chironomidae Polypedilum scalaenum (Schrank), P. bicrenatum Kieffer, Cryptochironomus gr. defectus, Dicrotendipes nervosus (Staeger), C. plumosus, Procladius ferrugineus, and Tanytarsus gr. gregarius, Oligochaeta T. newaensis, T. tubifex, Limnodrilus hoffmeisteri, and P. hammoniensis, Mollusca Viviparus viviparus, Valvata piscinalis, Pisidium sp., and D. polymorpha. Several Ponto-Caspian introduced taxa inhabit the present Kama River, including the mollusk D. polymorpha, polychaete H. invalida, and three crustaceans D. haemobaphes, P. sarsi, and Corophium curvispinum. These taxa are also found in zoobenthos of the Volga. The abundance of D. polymorpha became significant since late 1980s with local biomasses of 200–370 g/m2. Although uncommon, H. invalida had been found in the lower Kama. The Chinese crab E. sinensis had been recorded in the upper Kamskoye reservoir in 2001. The total biomass of zoobenthos in the Kama varies from 5 to 31 g/m2, and without mollusks is 2–4 g/m2. High biomass values over 60 g/m2 typically occur in the upper Kama. Long-term observations showed increases in the abundance of the mollusks Viviparus viviparus and D. polymorpha. At the same time, Oligochaeta and Chironomidae decreased in biomass. Average zoobenthic biomass in Votkinskoye reservoir (2003) is 141 g/m2, while it was 12–24 g/m2 in the Kamskoye reservoir in 2002–2004. 2.9.1.5.5 Fish Studies of the fishes in the Kama River has been carried out for the last two centuries. The first faunistic descriptions did not contain complete information on fish species and differed greatly from modern taxonomy. However, 24–43 fish species were recorded from those times. Before filling of the Kamskoye reservoir in 1954, 42 fish species had been recorded in the middle Kama. After dam construction in the middle Volga and Kama River, anadromous fish such as lamprey, beluga, Russian sturgeon, two species and one subspecies of herring, sheefish, and Caspian salmon were lost from the fish community. Concomitantly, catfish disappeared and the natural habitat of brook trout was reduced. As a result, only 32 fish species were found in the middle Kama and its tributaries in the 1970s. Further modifications in the fish community were realized with the appearance of chub and Amur sleeper, by natural recolonization of catfish, and invasion of sardelle from the Volga basin. The white-finned gudgeon inhabits a number of lower reaches of tributaries, and brook trout, Volga zander, spine fish, and round bullhead can now be found in fish catches. Presently, there are 41 fish species in the upper and middle Kama. During the two centuries of observation, fish composition in the Kama changed little, although significant
49
Chapter | 2 Volga River Basin
modifications occurred in structure of communities. As in earlier times, the Ponto-Caspian freshwater species make up most of the species, being dominated by bream, whiteeye bream, blue bream, silver bream, rudd, asp, bleak, chub, sneep, sabrefish, belica, and chub. The boreal plains complex is made up of pike, golden and silver crucian, roach, ide, dace, gudgeon, lake minnow, tench, spined loach, perch, and ruff. The boreal sub-mountain complex consists of beeper, brook trout, grayling, riverine minnow, loach, and bullhead. The upper tertiary plain complex consists of starlet, sazan, catfish, loach, zander and Volga zander. The remaining fish taxa are represented by 1–3 species. The burbot comprises the freshwater Arctic group, sardelle, spine fish, and round bullhead form the Ponto-Caspian sea group, the Amur sleeper forms the Chinese plain group (Dgebuadze & Slyn’ko 2005).
2.9.1.6 Management and Conservation There are 12 administrative regions with a total population of over 29 million in the Kama catchment. Among them, >10 million (40%) inhabit the adjacent riverine floodplain. The catchment is rich in minerals and several thousand mines are active here. Ferrous and non-ferrous metallurgy, coal industry, oil processing, and engineering and chemical industries thrive in the catchment. Forests occupy about 14 million ha of the catchment area. Kama reservoirs, similar to the Volga reservoirs, had been built for multi-purpose goals of water supply, water transport, and timber rafting, among others. Industrial and municipal discharge from river-side cities are the main sources of pollution. Three reserves are found in the Kama catchment (Sokolov & Syroechkovsky 1988, http://www.sevin.ru/ natreserves/). The Volga-Kamsky Reserve founded in 1960 is located in Tatarstan and occupies 80 km2. The Basegi Reserve (1982, 190 km2) and the Vishera Reserve (1991, 2400 km2) are situated in the Perm’ oblast. Most of the Volga-Kamsky Reserve is covered by forests of taiga, oak, and steppe. Flora of the reserve consists of over 840 species of plants. Faunistically, about 200 species of birds, 55 species of mammals, 30 species of fish, and a number of amphibians and reptiles inhabit the reserve. Both flora and fauna include rare species registered in the Red Book of Russia.
2.9.2. The River Oka 2.9.2.1 Introduction The Oka is a relatively large river in Russia, and one of the two largest tributaries of the Volga. The origin of its name is not exactly known, although the most likely are the Lithuanian word ‘aka’ meaning ‘spring’ or Finnish word ‘joki’ meaning ‘river’. Before Slavic colonization, the upper Oka was inhabited by Baltic tribes (polekhi) and
the middle and lower Oka by Finnish tribes (meshchera, muroma). Sites of Stone Age man were discovered on the left bank of the Oka between the Dmitriyevy Mountains and Murom. In 15th–16th century the river acted as the defence line of the Moscow State against Tatars raids from the south.
2.9.2.2 Paleography of the Catchment The present Oka catchment was formed in the post-glacial period. The catchment occupies the central part of the Russian plain that is covered by a layer of sedimentary rocks. Within the Moscow syncline, this sedimentary layer exceeds 3000 m in depth. Lowlands, at 50% of the catchment area (Yablokova 1973). The climate of the catchment is continental-temperate and is similar to that of the middle Volga. Mean air temperature in January ranges from 11 C in the north to 9 C in the south; and from 17 to 20 C, respectively, in July. Annual rainfall averages 450–680 mm, decreasing from northwest to southeast.
2.9.2.4 Geomorphology, Hydrology, and Biogeochemistry The Oka flows from west to east. Headwaters of the river are in the forest-steppe black earth (chernozem) lands of the Kursk province. Headwaters are fed by underground springs from Devonian deposits. Banks of the upper Oka are steep, and its width up to Kaluga varies from 60 to 160 m. Its right bank is for the most part higher than the left. From its headwaters, the Oka enters an area of coal mining, changing its direction at right angles several times. In this section, together with its tributary Ugra, the river flows through the Central Russian upland and chernozem forest-steppe zone. Downstream from the confluence with the Moksha River, the Oka leaves the coal-mining area and enters a region of
50
Upper-Jurassic sandstones. Here the right bank, ‘Ryazan side’, is high and undercut, whereas the left bank, ‘Meshchera side’, is low, wooded and boggy. A wide bottomland of vast coniferous forests lies on the Meshchera side with a base of impervious Jurassic clays covered with layers of sand. The Ryazan side is forest-poor and incised with gullies that stretch to the Pronya confluence. The Oka then turns north and then acutely southeast. The middle Oka transverses the Kasimovskaya limestone ridge made up of carboniferous rocks. Downstream from its confluence with the Moksha, the river flows north and then northeast to its mouth. Here the left side is bounded by the Dmitriyevy and Bolotovy Mountains and the right by the historically significant, coniferous-forest lowlands of Murom. Downstream of the town of Murom, the left bank lowers and the right is composed of Permian marls and gypsums. Downstream from the town of Pavlov is the steep Gorbatovskaya bend where the tributary Klyazma enters from the left. Between the tributary and Gorbatovskaya bend, the Oka runs through a wide depression called Oka gate. Further downstream, the left bank is low, whereas the right-bank borders the Dyatlovy Mountains. At the confluence of the Oka and Volga sits a large industrial and cultural center, the city Nizhni Novgorod. The total number of rivers and streams in the catchment is >19 000, and about 1600 of these are >10 km (Yablokova 1973). Left-side tributaries drain mixed coniferous–deciduous forests of sod-podzolic soils of different grain sizes mixed with alluvial soils in floodplains and bog-podzolic soils in poorly drained areas. Right-side tributaries drain forest-steppe where soils are mostly grey forest soils and leached chernozems. Floodplains on the right side of the river are heavily tilled. The flow regime of the Oka has a pronounced spring flood, and summer and winter low flows with periodic floods from rain events. Spring runoff contributes on average 58% (April–May), winter 14% (January–March, December), and summer–autumn 28% (June–November) to annual discharge. Minimum discharge usually occurs in February (Yablokova 1973). Mean annual discharge is 39.3 km3, maximum 58.3 km3, and minimum 21.6 km3. Maximal mean monthly discharge in May is 12 500 m3/s, a minimum of 827 m3/s occurs at a mean annual discharge of 1240 m3/s. Average annual discharge ranges from 4.9 L s1 km2 in the upper Oka to 5.4 L s1 km2 in the lower river, or 0.98– 600 m3/s, respectively. Year-to-year fluctuations in discharge before the Volga was regulated showed irregular cycles of 3–5-year long high-water periods (i.e. 1905– 1909, 1915–1917, 1926–1929) and 3–11-year long lowwater periods (i.e. 1910–1914, 1918–1925, 1934–1945, and 1948–1950) (Yablokova 1973). 2.9.2.4.1 Temperature The highest water temperature in the river is in July, averaging 21 C and ranging from 18.5 to 24.6 C. The river begins to freeze-over in late November early December and lasts on
PART | I Rivers of Europe
average 125–140 days. Ice thickness varies on average 45– 60 cm but can reach 95 cm in some years. In the upper river near the city Orel, the Oka is ice-free on average 235 days (early April to late November) and 210 days in its lower reach between Murom and Nizhni Novgorod. 2.9.2.4.2 Biogeochemistry The lower Oka belongs to the hydrocarbonate–calcium group. Water mineralization is high due to direct contact of surface waters with carbonates and inputs of highly mineralized ground waters. Mineralization is 260–570 mg/L during most of the year, decreasing to 130–140 mg/L in spring during high flows (Alekin 1948). From the source to its mouth, mineralization continuously increases due to dissolution of surface Dyas deposits, transition of podzolic-sandy soils in the north to gray podzolic soils of forest-steppe and rich chernozems in the south, and a decrease in rainfall from north to south concomitant with an increase in evaporation rate. Mineral content is mainly from SO2 and Ca (Alekin 1948). A dominance of HCO is clearly pronounced in the anion composition of the water, representing from 40–45% equivalent in the upper river (by Orel) to 26–35% equivalent in the lower river (by Nizhni Novgorod). In contrast, sulphates increase from 5–8% equivalence in the upper river to 15–20% equivalence in the lower river. Water pH during the ice-free period is 6.2–8.1 and highest in summer. Average turbidity ranges from 1400 g/m3 in the upper river to 190 g/m3 in the low river (Yablokova 1973). Low water colour (15–25 Cr–Co degree) is observed during winter. Water oxidization changes from 2–8 mg/L in summer to 4–19 mg/L in spring due to organic matter inputs from melting snow. Dissolved oxygen varies significantly during the year. Total nitrogen content averages 1.49 mg/L (Alekin 1948; Zenin 1965). Total phosphorus content at the mouth varies from 0.208 to 0.304 mg/L, total nitrogen from 1.80 to 3.21 mg/L, and carbon from 5.7 to 11.8 mg/L. Bottom sediments are composed of mostly small particles 0 C average daily temperature occurs around April 8 and to 90% of the biomass. Bosmina coregoni gibbera (Schoedler), B. longispina, B. crassicornis, Daphnia galeata, D. cucullata, D. cristata, Diaphanosoma brachyurum, D. orghidani, Mesocyclops leuckarti, Thermocyclops oithonoides, Eudiaptomus gracilis, Heterocope appendiculata, Limnosida frontosa, Leptodora kindtii, Bythotrephes longimanus are most common. Small organisms, that is Conochilus unicornis, C. hippocrepis (Schrank), Keratella cochlearis, and Kellicottia longispina Kellicott are numerous Rotifera, making up to 50 000/m3. Non-native species of Cyclops scutifer Sars and Asplanchna herricki Guerne that belong to the northern lacustrine complex probably came from water bodies of the catchment from 1960 to 1980. The southern species, Diaphanosoma orghidani, found in 2005 likely came from the upper Volga, it numbers about 2000/m3. Average zooplankton abundance during May–October is 40 000/m3 and biomass is 0.7 g/m3. Highest values (156–235 000/m3 and 2.8–4.0 g/m3) are usually observed in June–July in the lower river. 2.9.3.5.4 Zoobenthos Presently, 170 species of macrozoobenthos have been found in the flooded channel of the Sheksna (Bakanov 2002). The majority, up to 83% of the total, is made up by chironomids (60 species), mollusks (40), and oligochaetes (37). Oligochaetes Tubifex newaensis, T. tubifex, Limnodrilus hoffmeisteri, L. udekemianus Claparede, Potamothrix hammoniensis, and P. moldaviensis, chironomids Chironomus plumosus, and Procladius choreus, mollusks D. polymorpha and large representatives of Pisidiidae, the genus Amesoda and Sphaerium dominate zoobenthos numbers and biomass. The highest biomass of macrozoobenthos at 145– 200 g/m2 was found near the dam at a depth of 18–22 m. The chironomid Chironomus plumosus and oligochaete Tubifex tubifex made up most of the biomass (about 75%). Only one species under danger of extinction, mollusk Anisus vorticulus, was not included in the fauna list of macroinvertebrates in the Sheksna. Along the entire river, the nonindigenous Baikal amphipod Gmelinoides fasciatus was the single representative of crustacean (Bakanov 2002). In 2005, average macrozoobenthos biomass in the Sheksna reservoir was about 6 g/m2, while upstream of Cherepovets, in the river with flowing water it was 0.5–3.6 g/m2. 2.9.3.5.5 Fish Ichthyofauna of the Sheksna traditionally was of a mixture of rheophilous species (pike, perch, roach, ide, ruffe, bleak, etc.) and limnophilous species coming from Lake
Beloye. The first marked decrease in the number of species and their composition was observed in 1896 after the dam that separated Lake Beloye from the upper Volga basin was built, leading to the disappearance of Russian sturgeon, beluga, sterled and sazan. In 1970s, the number of species was 29, 25 in the 1980s, and 22 species are presently observed in catches. The following species are no longer observed since 1970s: minnow, grayling, zanthe, wels catfish, chudskoi whitefish, ludoga whitefish, smelt and river lamprey. Tench, eel and peled were observed at single times. In the 1980s, these species along with belica and loach have disappeared, and elets, chub, crucian carp, spined loach and bullhead became rare. In the 1990s, these latter species became extinct and white-eye bream, rudd, gudgeon, ide and zherekh were counted as rare. Now the ichthyofauna is made up of limnophilous fish species (Dgebuadze & Slyn’ko 2005). Before Sheksna was regulated, commercial catches were about 5 tons, dominating species was pike. At present, the annual catch equals 100 tons and the dominating species is bream.
2.9.3.6 Management and Conservation Anthropogenic stressors in the Sheksna are few. There are a number of diffuse pollution sources along the banks, diffuse runoff, and navigation effects. Water quality is estimated as ‘pure’ according to microbiological tests, and the water is mesotrophic according to chlorophyll and b- or a–b mesosaprobic. Poor water quality is apparent only at local sites. The Sheksna is monitored by a regional ecological service net, and the water chemistry has not changed in the last 40 years.
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Bakanov, A.I. 2002. Taxonomic composition and abundance of benthos in the Sheksna Reservoir in the late 20th century. Biology of Inland Waters 1, (In Russian). Bakanov, A.I. 2003. The contemporary state of the benthos in the Upper Volga within the Yaroslavl Region. Biology of Inland Waters 1, (In Russian). Bakanov, A.I. 2005. Benthos in the Cheboksary reservoir: taxonomic composition and abundance. Biology of Inland Waters 1, (In Russian). Balkov, V.A. 1978. Water Resources of Bashkiria. Bashkiria Book Publisher, Ufa, (In Russian). Balkov, V.A. 1979. Influence of Karst on the Rivers Run-Off in European Territory of the USSR. Hydrometeoizdat, Leningrad, (In Russian). Belevsky, P.E. (ed). 1892. Volga. Encyclopedic Dictionary 7 Brokgause & Efron, SPb, (In Russian). Belko, N. 2004. Reserved Meshera. Logata, Moscow, (In Russian). Behning, A.L. 1928. Data on the hydrofauna of the River Kama. Proceedings of the Volga Biological Station 94–5, (In Russian). Berg, L.S. 1948. Freshwater Fishes of USSR and Adjacent Countries Vol. 1, AS USSR, Moscow-Leningrad, (In Russian). Berg, L.S. 1949a. Freshwater Fishes of USSR and Adjacent Countries Vol. 2, AS USSR, Moscow-Leningrad, (In Russian). Berg, L.S. 1949b. Freshwater Fishes of USSR and Adjacent Countries Vol. 3, AS USSR, Moscow-Leningrad, (In Russian). BioDat: Informational Resources (http://www.biodat.ru/). Borodich, N.D., and Lyakhov, S.M. 1983. Zoobenthos. Kuibyshev Reservoir. Nauka, Leningrad, (In Russian). Butorin, N.V., and Ekzertsev, V.A. (eds). 1978. Ivankovo Reservoir and its Life, Nauka, Leningrad, (In Russian). Butorin, N.V., and Mordukhai-Boltovskoy, P.D. (eds). 1979. The River Volga and its Life, Junk Publishers, The Hague. Bylinkina, A.A., Trifonova, N.A., Kudryavtseva, N.A., and Kalinina, L.A. 1982a. Select data on hydrochemistry of the Kama reservoirs. Hydrobiological Characteristics of the Volga Basin Reservoirs, Nauka, Leningrad, (In Russian). Bylinkina, A.A., Trifonova, N.A., Kudriavtseva, N.A., Kalinina, L.A., and Genkal, L.F. 1982b. Hydrochemical regime of Sheksna Reservoir and waterbodies of Northern-Dvina system. Ecological Study of Waterbodies of Volga-Baltic and Northern-Dvina Water Systems, Nauka, Leningrad, (In Russian). Chernyaev, A.M. (ed). 2000. Waters of the Russia, Aqua-Press, Ekaterinburg, (In Russian). Daletchina, I.N., and Silnikova, G.V. 2001. Characteristic of phytoplankton in the Volgograd Reservoir during 1999–2000. Fundamental and Applied Aspects of Water Ecosystems Functioning: Problems and Future Trends of Hydrobiology and Ichthyology in XX Century. Saratov State University, Saratov, (In Russian). Dementieva, A.A. 1985. Zooplankton in the Votkinsk reservoir. Biology of Waterbodies in the Western Urals, Permsky State University, Perm’, (In Russian). Devyatkova, T.P., and Trutnev, A.Y. 1983. Peculiarities of forming flow velocity and water discharge in Kamskoye reservoir. Integrated Investigations of Rivers and Reservoirs in the Urals, Permsky State University, Perm, (In Russian). Dgebuadze, Y.Y., and Slyn’ko, Y.V. (eds). 2005. Alien Species in Holarctic (Borok-2). Book of Abstracts. 2nd International Symposium Rybinsk – Borok, (In Russian). Genkal, S.I., Koroleva, N.L., Poptchenko, I.I., and Burkova, T.N. 1992. The first finding of Actinocyclus variabilis in the Volga River. Biology of Inland Waters. Information Bulletin 94, (In Russian). Genkal, S.I., and Yelizarova, V.A. 1996. Actinocyclus variabilis (Makar.) Makar., a new representative of Bacillariophyta in the Rybinsk Reservoir. Biology of Inland Waters 1, (In Russian).
PART | I Rivers of Europe
Gerasimova, N.A. 1996. Phytoplankton in Saratov and Volgograd reservoirs. Samara Science Centre, Togliatti, (In Russian). Gromov, V.V. 1951. Changes of bottom fauna in the Kama River under influence of waste waters. Izvestia of YeNI 13, (In Russian). Gusakov, V.A. 2001. The Effect of the Hydrological Regime in the Rybinsk Reservoir on the Distribution and Dynamics of Benthic Cyclops. Water Resources 28. Isachenko, T.I., and Lavrenko, Y.M. 1980. Botanial and geographical zoning. Vegetation in the European part of the USSR, Nauka, Leningrad, (In Russian). Ivanov, D.I., and Pechnikov, A.S. 2004. Contemporary State of Fisheries in Russian Inland Water Bodies. GosNIORKh, St. Petersburg, (In Russian). Klige, R.K., Kovalevsky, V.S., and Fedorchenko, E.A. 2000. Influence of the global climatic changes on the water resources of the Volga basin. Global Changes of the Environment, Scientific World, Moscow, (In Russian). Komarov, I.K. 1997. Revival of the Volga – a Step to Salvation of Russia. Ecology, Moscow, (In Russian). Komlev, A.M., and Cernykch, E.A. 1984. Rivers of the Perm’ Oblast. Permsky Book Publisher, Perm’, (In Russian). Kopylov, A.I. (ed). 2001. Ecological Problems of the Upper Volga, YSTU Press, Yaroslavl, (In Russian). Kortunova, T.A. 1983. Zooplankton and its production in the Kamskoe reservoir. Integrated Investigations of Rivers and Reservoirs in the Ural, Permsky State University, Perm’, (In Russian). Kortunova, T.A. 1985. Variations in zooplankton in the Kamskoe reservoir during vegetation season. Biology of Waterbodies in the Western Ural, Permsky State University, Perm, (In Russian). Kuzin, P.S. 1960. Classification of the Rivers and Hydrological Regions of the USSR. Hydrometeoizdat, Leningrad, (In Russian). Kuzmin, G.V., and Okhapkin, A.G. 1975. Phytoplankton of the River Volga at the route of building the Cheboksary Reservoir and prognosis of its algological regime. Anthropogenic Factors in the Life of Waterbody, Nauka, Leningrad, (In Russian). Kuznetsova, L.A., and Rassadnikova, G.I. 1983. Physical and mechanical characteristics of the bottom sediments in the Votkinsk reservoir. Integrated Investigations of Rivers and Reservoirs in the Urals, Permsky State University, Perm’, (In Russian). Labunskaya, E.N. 1995. The Phytoplankton of Lower Volga and Northern Caspian, its Significance in Estimation Water Quality. Dissertation. Moscow State University, Moscow, (In Russian). Lipatova, V.V. 1980. Vegetation in floodplains. Vegetation in the European part of the USSR, Nauka, Leningrad, (In Russian). Litvinov, A.S. (ed). 2002. Modern State of the Sheksna Reservoir Ecosystem, YSTU Press, Yaroslavl, (In Russian). Lukyanenko, V.I., Riv’er, I.K., Litvinov, A.S., and Kopylov, A.I. 1994. Ecology of the Upper Volga: Modern State, Problems and their Solution. Yaroslavl, (In Russian). Lyashenko, O.A. 1999. Phytoplankton and chlorophyll content as index of trophic status of Ivankovo Reservoir. Water Resources 26(1). Lyashenko, O.A. 2000. Seasonal dynamics and long-term changes of phytoplankton and chlorophyll content in the Uglich Reservoir. Biology of Inland Waters 3, (In Russian). Malinina, Yu.A., Dalechina, I.N., and Filinova, E.I. 2005. Hydrobiological estimation of the water quality in the Volgograd reservoir in a zone of influence of industrial center. Actual Problems of Efficient Use of Biological Resources of Reservoirs, Publisher House, Rybinsk, (In Russian). Mineeva, N.M. (ed). 2000. Modern Ecological Situation in the Rybinsk and Gorky Reservoirs: the State of Biological Communities and Perspectives of Fish Reproduction, YSTU Press, Yaroslavl, (In Russian).
Chapter | 2 Volga River Basin
Mineeva, N.M. 2004. Plant pigments in the water of the Volga river reservoirs. Nauka, Moscow, (In Russian). Mokeeva, N.P. 1964. Algae flora of the River Oka. Proceedings of Zoological Institute AS USSR 32, (In Russian). Mordukhai-Boltovskoy, P.D., and Dzuban, N.A. 1976. Variations in composition and distribution of the River Volga fauna under anthropogenic impact. Biological Production Processes in the River Volga Basin, Nauka, Leningrad, (In Russian). Nechvalenko, S.P. 1976. Bottom fauna in the Volgograd Reservoir. The Volgograd Reservoir, Privolzhckoye, Saratov, (In Russian). Obidientova, G.V. 1975. Forming of the River Systems in the Russian Plain. Moscow, (In Russian). Okhapkin, A.G. 1994. Phytoplankton in Cheboksary Reservoir. Samara Science Centre, Togliatti, (In Russian). Okhapkin, A.G., Mikulchik, I.A., Korneva, L.G., and Mineeva, N.M. 1994. Phytoplankton in Gorki Reservoir. Samara Science Centre, Togliatti, (In Russian). Pakhtusova, N.A. 1969. Geological structure. Hydrogeology of the USSR. V. 44. Arkhangelsk and Vologda oblast, Nedra, Moscow, (In Russian). Pautova, V.N., and Nomokonova, V.I. 2001. The Dynamics of Phytoplankton in the Lower Volga River – From the River to Reservoirs Cascade. Samara Science Centre, Togliatti, (In Russian). Pavlinova, R.M. 1930. Biological study of the River Volga within the site from Gorodets to Sobchinsky zaton in 1926 and 1927. Proceedings of the Institute of Constructions of the Central Committee of Water Protection 11, (In Russian). Pavlov, D.S., Dgebuadze, Y.Y., Korneva, L.G., and Slyn’ko, Y.V. (eds). 2003. Invasions of alien species in Holarctic. Proceedings of the US – Russian Workshop, 27–31 August 2001, Borok, (In Russian). Pirogov, V.V., Fil’chakov, V.A., Zinchenko, T.D.,Karpyuk, M.I., and Edsky, L.B. 1990. New elements in the composition of benthic fauna in the Volga-Kama reservoir cascade. Zoological Journal 69 (9), (In Russian). Pivovarova, Z.I., and Stadnik, V.V. 1988. Climatic Parameters of the Solar Radiation as Source of Energy at the USSR Territory. Hydrometeoizdat, Leningrad, (In Russian). Poptchenko, I.I. 2001. Species Composition and Dynamics of Phytoplankton in Saratov Reservoir. Samara Science Centre, Togliatti, (in Russian). Reserves (http://www.water.zapovednik.com/). Reserves of Russia (http://www.sevin.ru/natreserves). Reshetnikov, Y.S. 1998. Annotated Catalog of Cyclostomes and Fishes of the Continental part of Russia. Nauka, Moscow, (In Russian). Savinov, Y.A., and Filenko, R.A. 1965. Hydrogeological regions of the Vologda oblast. North-West of the European USSR. Pt 4 Leningrad, (In Russian). Shilova, A.I., and Zelentsov, N.I. 2003. Fauna of Chironomidae (Diptera, Chironomidae) in the Upper Volga basin. Biology of Inland Waters 2, (In Russian). Shklyaev, A.S. 1964. Patterns in Distribution of Precipitations and Drainage at the Northern and Southern Ural. Permsky State University, Perm’, (In Russian). Shmidt, O.Y. (ed). 1928a. The Volga. Grand Soviet Encyclopedia. Vol. 12. Soviet Encyclopedia, Moscow, (In Russian). Shmidt, O.Y. (ed). 1928b. The Kama. Grand Soviet Encyclopedia Vol. 30 Soviet Encyclopedia, Moscow, (In Russian). Shtina, E.A. 1968. Basic features of phytoplankton in the River Kama. Volga-1. Book of Abstracts. Togliatti, (In Russian). Shurganova, G.V. 1987. Dynamics of Species Structure of Zooplankton Community Under its Formation (by example of Cheboksary
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reservoir). Dissertation thesis, Moscow State University, Moscow, (In Russian). Shurganova, G.V., Cherepennikov, V.V., Krylov, A.V., and Artel’ny, E.V. 2005. Spatial distribution and peculiarities of basic zooplankton cenoses in Gorky reservoir. Biological Resources of Freshwaters: Invertebrates, Rybinsk Publisher House, Rybinsk, (In Russian). Sokolov, V.Y. (ed). 1988. Flora and Fauna in Reserves of the USSR, Nauka, Moscow, (In Russian). Sokolov, V.Y. and Syroechkovsky, Y.Y. (eds). 1988. Reserves of the European part of RSFSR Vol. 1. Mysl’, Moscow, (In Russian). Sokolov, V.Y. and Syroechkovsky, Y.Y. (eds). 1989. Reserves of the European part of RSFSR Vol. 2. Mysl’, Moscow, (In Russian). Stolbunova, V.N. 1999. Long-term variation in zooplankton communities in Ivankovo and Uglich reservoirs. Biology of Inland Waters 1, (In Russian). Svetlov, P.G., 1936. Oligochaeta found during the Kama expedition in 1935. Izvestia of Biological NII of Perm’ State University. 10, (In Russian). Tauson, A.O. 1947. Water Resources of Molotovskaya oblast. Molotov, (In Russian). Timokhina, A.F. 2000. Zooplankton as a Component of the Ecosystem of Kuibyshev Reservoir. Samara Science Centre, Togliatti, (In Russian). Tretyakova, S.A. 1989. Phytoplankton of the Kama reservoirs (Kamskoe and Votkinskoe). Hydrobiological Characteristics of Waterbodies in the Urals, Sverdlovsk, (In Russian). Trifonova, I.S. (ed). 2003. Lower Volga Phytoplankton. Reservoirs and Lower Reaches of the River, Nauka Press, St. Petersburg, (In Russian). Vikulina, Z.A. and Znamensky, V.A. (eds). 1975. Hydrometeorological Regime of Lakes and Reservoirs in the USSR. Reservoirs of the Upper Volga, Hydrometeoizdat, Leningrad, (In Russian). Vodeneeva, E.L. 2000. The state of the phytoplankton community in the estuarine zone of the River Oka in 1997–1998. Proceedings of the Biological Department of the N.I. Lobachevsky Nizhegorodsky State University Vol. 3. Nizhni Novgorod, (In Russian). Voloshko, L.N. 1971. Species composition of phytoplankton in the Lower Volga River and its Delta. Botanical Journal 56, (In Russian). Wikipedia – Open Encyclopedia (http://ru.wikipedia.org/). Yablokova, Y.Y. (ed). 1973. Resources of the surface waters in the USSR. The Upper Volga region Vol. 10, Pt 1. Hydrometeoizdat, Moscow, (In Russian). Yakovlev, V.N. (ed). 2000. Catalog of Plants and Animals of Volga River Basin Waterbodies, YSTU, Yaroslavl, (In Russian). Yesyreva, V.I. 1945. Algae flora of the River Volga from Rybinsk to Gorky. Proceedings of the Moscow State University Botanic Garden. 5 (82), (In Russian). Yesyreva, V.I. 1968. Phytoplankton of the River Oka. Abs. 1st Conf. on the Study of Water Bodies in the Volga Basin ‘Volga-1’,Togliatti, (In Russian). Yoffe, T.I. 1968. Review on realization of acclimation of the invertebrates for fish in reservoirs. Izvestiya GosNIORKh. 67, (In Russian). Zakonnov, V.V. 2005. Origin and transformation of bottom sediments in the Volga river reservoirs. Nature and Resources, Ecological, Social and Economic Problems of Environment in Large River Basins, MediaPress, Moscow, (In Russian). Zenin, A.A. 1965. Hydrochemistry of the River Volga and its reservoirs. Leningrad, (In Russian). Zinchenko, T.D. 2002. Chironomids of surface waters in the Middle and Lower Volga basins (Samara district). Ecological and Faunistic Review. Togliatti, (In Russian). Znamensky, V.A. and Chigirinsky, P.P. (eds). 1978. Hydrometeorological regime of the lakes and reservoirs in the USSR. Kuibyshev and Saratov Reservoirs Hydrometeoizdat Leningrad, (In Russian).
Chapter 3
The Danube River Basin Nike Sommerwerk
Christian Baumgartner
J€ urg Bloesch
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), M€ uggelseedamm 310, 12587 Berlin, Germany
Donauauen National Park GmbH, 2304 Orth an der Donau, Schloss Orth, Austria
International Association for Danube Research (IAD), Stauffacherstrasse 159, 8004 Z€ urich, Switzerland Eawag, Swiss Federal Institute of Aquatic € Science and Technology, Uberlandstrasse 133, 8600 D€ ubendorf, Switzerland
Thomas Hein
Ana Ostojic
Momir Paunovic
University of Natural Resources and Applied Life Sciences, Vienna, Institute of Hydrobiology and Aquatic Ecosystem Management, Max – Emanuelstrasse 17, 1180 Vienna, Austria WasserCluster Lunz, Dr. Carl-KupelwieserProm. 5, 3293 Lunz/See, Austria
University of Zagreb, Faculty of Science, Division of Biology, Rooseveltov trg 6, 10000 Zagreb, Croatia
Institute for Biological Research, 142 Despota Stefana Boulevard, 11060 Belgrade, Serbia
Martin Schneider-Jacoby
Rosi Siber
Klement Tockner
EuroNatur – European Nature Heritage Fund, Konstanzer Str. 22, 78315 Radolfzell, Germany
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3.1. 3.2. 3.3. 3.4. 3.5. 3.6.
3.7.
Introduction Historical Aspects Palaeogeography and Geology Geomorphology Climate and Hydrology Biogeochemistry, Water Quality and Nutrients 3.6.1. General Characteristics 3.6.2. Water Quality Biodiversity 3.7.1. Riparian Vegetation 3.7.2. Vegetated Islands 3.7.3. Macrophytes 3.7.4. Macroinvertebrates 3.7.5. Fish 3.7.6. Avifauna 3.7.7. Wetland Mammals 3.7.8. Herpetofauna
Rivers of Europe Copyright Ó 2009 by Academic Press. Inc. All rights of reproduction in any form reserved.
3.8. 3.9.
3.10.
Human Impacts, Conservation and Management Major Tributaries and the Danube delta 3.9.1. Inn 3.9.2. Morava 3.9.3. V ah 3.9.4. Drava 3.9.5. Tisza 3.9.6. Sava 3.9.7. Velika Morava 3.9.8. Olt 3.9.9. Siret 3.9.10. Prut 3.9.11. Danube delta Conclusion Acknowledgements References
59
60
FIGURE 3.1 Digital elevation model (upper panel) and drainage network (lower panel) of the Danube River Basin.
PART | I Rivers of Europe
61
Chapter | 3 The Danube River Basin
3.1. INTRODUCTION
3.2. HISTORICAL ASPECTS
It was July 10 in 1648 when Pope Innocent X approved the construction of the ‘Four-Rivers-Fountain’ at the Piazza Navona, probably the most beautiful square in Rome. He asked the famous sculptor Gian Lorenzo Bernini to finish the fountain by 1650, a Holy Year. The four rivers were the Nile of Africa, the Ganges of Asia, the Rio del la Plata of the Americas and the Danube of Europe (Weithmann 2000). The Danube is the European river par excellence; a river that most effectively defines and integrates Europe. It links more countries than any other river in the world. The Danube River Basin (DRB) collects waters from the territories of 19 nations and it forms the international boundaries for eight of these (Figure 3.1). The river’s largely eastward course has served as a corridor for both migration and trade, and a boundary strongly guarded for thousands of years. The river’s name changes from west to east from Donau, Dunaj, Duna, Dunav, Duna˘rea, to Dunay, respectively. The names of the river (Danube, as well as Don, Dnjeper and Dnjester) most likely originate from the Persian or Celtic word Danu, which literally means flowing. It also may stem from the Celtic ‘Don, Na,’ or ‘two rivers,’ because the Celts could not agree on the source of the Danube (cited in Wohl in press). In this chapter, we provide an overview of the DRB, including the three main sections (Upper, Middle, Lower Danube), the delta and 11 major tributaries (Figures 3.1 and 3.2, Table 3.1). This chapter builds upon several textbooks on the Danube, including Liepolt (1967) and Kinzelbach (1994) and, among many other sources, on information derived from the International Commission for the Protection of the Danube River (ICPDR).
In 1908, an 11.1-cm large statuette, the so-called ‘Venus of Willendorf’, was excavated by the archaeologist Szombathy near the village of Aggsbach (Austria, Wachau valley), dating back 25 000 years BC. North of this place, in Dolvi Vestonica, a large meeting place of mammoth hunters from the same period was discovered 1924–1952. These two examples demonstrate that the Danube valley has experienced a long history of human occupation and cultural development that started during the Paleolithic period. Between 8500 and 500 BC, permanent fishery and hunting settlements were erected in Lepinski Vir (Iron Gate Gorge) and Vinca (in the suburban sector of Belgrade) (Weithmann 2000). Starting >7000 years ago, farmers from Anatolia entered Europe and expanded throughout the continent. The Danube was most likely one of the major expansion pathways. There is evidence that a major flood that entered the Black Sea from the Mediterranean (i.e., the diluviam) probably forced the westward migration of these early farmers. Between 750 and 500 BC, the Celts occupied the entire Upper Danube valley. The best known place was the Heuneburg near Riedlingen where a large Celtic wall circled the entire hill. The Celts respected the Danube as a bringer of life and death and their sole connection to the outside world. They called it the Great Mother of Gods – Danu. The Celts were stimulated by Greek culture. The Greek poet Hesiod first mentioned the Danube in about 700 BC as the ‘beautifully flowing Istros’, the son of Tethys and Okeanos. Herodotus wrote in 450 BC that the (H)Istros is the largest river in the world, a river that ‘has its source in the country of the Celts near the city Pyrene, and runs through the middle of Europe, dividing it into two portions . . . before it empties itself into the Pontos Euxeinos’. During the war against the Scythes in 513/12 BC, Dareis, the great Persian king, sailed up the Danube to explore a suitable location for constructing a bridge for his army. The first European waterway was established during the Greek period and connected the Adriatic Sea with the Black Sea via the Ocra pass, the Sava River and the Lower Danube. Today, there exist plans to re-establish this ancient Danube–Adriatic waterway for navigation. The Danube was always both a migration corridor as well as a frontier. During the Roman Empire, the ‘Limes’ along the Danube as well as along the Olt River protected the Empire agains the ‘Barbarians’. The Romans erected fortifications along the Danube such as Castra Regina (Regensburg), Juvavum (Salzburg), Lentia (Linz), Vindobona/ Vindomana (Vienna) and Aquincum (Budapest), among many others. The Limes played an important role even long after the fall of the Roman Empire, for example, it was used as a fortification against the Mongolian invasion in 1241. The armies of Charlemagne also marched along the remnants of the Roman Limes, as did the Crusaders. The boundary between Orient and Occident is roughly just east of the
FIGURE 3.2 Longitudinal profile of the Danube River and its major
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TABLE 3.1 General characterization of the Danube River Basin Upper Danube
Middle Lower Delta Inn Danube Danube Danube
Mean catchment 793 435 355 9 elevation (m) 104 932 473 214 218 387 4560 Catchment area (km2) 25.3 125.9 188 205 Mean annual discharge (km3) Mean annual 101.2 79.2 60.5 43.2 precipitation (cm) 6.7 8.8 9.2 10.7 Mean air temperature ( C) Number of ecological 4 8 7 1 regions Dominant (25%) 2; 70 52 9 55 ecological region(s) Land use (% of catchment) Urban Arable Pasture Forest Natural grassland Sparse vegetation Wetland Freshwaterbodies Protected area (% of catchment)
1260
378
V ah
Drava
473
760
Tisza
Sava
350
Velika Morava
541
631
Iskar 655
Olt
Siret
621
Prut
485
267
26 128 27 267 19 660 40 087 156 087 95 793 37 571 8860 24 439 46 289 28 568 23.1 3.47 4.35 17.1 25.0 49.6 8.74 1.70 5.43 6.63 2.11 136.0
63.8 79.3
112.1
65.8
105.4
77.8
62.1
67.6
62.4
59.8
8.6 2
9.2 4
9.3 3
9.4 2
7.9 4
7.7 5
8.5 4
9; 58
9; 13
13; 22
13; 22; 28
4.6 2
8.1 7.5 4 2
7.3 3
2; 70
52; 70 13; 52
2; 52
52
27; 52
9
4.7 31.5 13.4 37.3 6.4 5.5 0.3 0.9
4.1 44.8 7.8 35.4 5.9 0.6 0.5 0.9
6.0 54.1 6.7 26.6 4.1 0.3 0.7 1.5
2.4 22.9 1.1 5.8 4.6 1.4 49.0 12.8
2.9 14.7 15.4 35.2 13.5 17.0 0.3 1.0
6.0 6.4 59.4 45.6 3.0 6.4 29.3 36.8 1.8 3.8 0.0 0.2 0.0 0.2 0.5 0.6
3.5 28.7 7.9 45.8 9.0 3.9 0.3 0.9
4.9 48.1 11.1 30.0 4.4 0.1 0.7 0.7
2.1 36.9 5.8 45.3 8.4 0.7 0.1 0.7
1.7 38.8 7.3 42.6 8.8 0.5 0.0 0.3
6.3 42.2 4.3 30.3 14.6 1.6 0.1 0.6
5.0 36.5 12.6 37.4 6.7 0.4 0.4 1.0
7.7 38.8 9.4 38.2 3.9 0.2 0.5 1.3
4.9 57.3 7.3 27.7 0.6 0.0 1.2 1.0
0.5
2.8
0.7
89.1
0.9
7.7 11.2
0.3
3.0
0.8
0.0
0.0
0.0
0.3
3.3
2.0 2.9 3 217
2.0 3.0 3 143
2.0 3.0 2 227
2.2 3.0 1 0
2.0 2.9 3 31
2.0 3.0 3 17
2.0 3.0 3 49
2.0 3.0 2 45
2.0 2.9 2 18
2.0 2.9 2 3
2.1 3.0 2 2
2.0 3.0 3 27
2.0 3.0 3 18
2.0 3.0 2 3
49 14 3 91
56 12 13 85
50 5 5 92
35 7 1 116
37 3 1 170
17 6 2 87
29 5 3 75
41 5 3 112
15 832
2876
3664
702
2763
2212
1703
943
2.0 3.0 3 46
59 13 7 140
72 12 23 95
70 7 18 101
70 4 0 34
15 2 2 84
45 7 2 129
37 n.d. 0 133
27 726
4886
1746
2145
31 317
8771
4342
Catchment boundaries: see Figure 3.1a. The Iskar River is not treated in detail in the text. n.d.: Not determined. For data sources and detailed explanation see Chapter 1.
PART | I Rivers of Europe
Water stress (1–3) 1995 2070 Fragmentation (1–3) Number of large dams (>15 m) Native fish species Nonnative fish species Large cities (>100 000) Human population density (people/km2) Annual gross domestic product ($ per person)
Morava
Chapter | 3 The Danube River Basin
Iron Gate and south of Belgrade. The division into two parts has remained for most of its history, making the Danube ‘aqua contradictionalis’, the river of fatality as mentioned by Pope Innocent IV. The Roman Empire influenced the Danube region for >500 years, starting with the expansion of the empire toward the Danube during the regency of Octavianus Augustus. The Upper Danube, down to the Iron Gate, then changed its name from (H)Ister (Istros) to Danuvius (Danubis). The Romans established several provinces along the Danube, including Raetia, Pannonia, Dacia, Moesia and Scythia. Dacia was the only province north of the Danube, but it was given up by Emperor Aurelian in 270 AD. The retreat of the Romans from Dacia created a power-vacuum and contributed to a global political and military crisis at that time. In the context of the Roman Empire, the Danubian provinces were primarily of military interest and the people in Rome and the Mediterranean area considered these provinces as culturally undeveloped. The battle at Adrianopel (Edirne), 378 AD, marked the beginning of the end of the Roman Empire. An unstable period followed after the fall of the Empire and the subsequent invasion by the Barbarians. German tribes and later Turkic Avars (‘Huns’ is often used synonymously for Avars) entered the area and crossed the Danube; in particular during winter when the Middle and Lower Danube were frozen. The Goths left Pannonia at the end of 469 and crossed the frozen Danube north of Aquincum (Budapest). The Langobards replaced the Goths in Pannonia, remaining for >100 years. Moesia was the only Romanian province along the Danube that remained for longer periods under the control of Constantinople, the capital of the Eastern Roman Empire. The Avars, a steppic tribe that forced the Langobards to leave the area (the Langobards settled in northeast Italy), established their Khangat in the Danube–Tisza area. For short periods, they expanded their area to near Constantinople. In the 7th century, Slavs (Croatians and Serbians) originating from north of the Carpathian Mountains and nomades (Bulgarians) from the Volga area entered the Danube region and replaced the Avars in the Sava–Drava and Lower Danube, respectively. Later, the Avars disappeared from the Pannonian plain, and in 895 AD the Magyars, originating from the northeast Ural Mountains and western Sibiria, arrived in the Pannonian plain and established their regency. The Upper Danube was mainly under the control of the Bavarians. Up to 1050 AD, the Danube was primarily a migration corridor for warriers. During the 11th century, the river became an important route for pilgrims visiting the Holy Country and Jerusalem. However, the Crussards could not stop the loss of the Holy Country to the Ottoman Empire. The Ottoman Empire influenced the Danube region for 500 years. The ‘foreign’ rule by the Turks has often been blamed for the present state of under-development in the Middle and Lower Danube. Bulgaria was the first country under Ottoman control (1393–1878). In 1389, Serbia lost at the memorable battle of Kosovo polje against the Ottomans. Soon after,
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the entire Danube downstream of Iron Gate became under Ottoman control. During the Ottoman Empire, the Danube was again a ‘Limes’ but this time to protect the northern parts against the threats entering from the south. Hungarians (King Sigismund), together with French, Burgundian and German armies, tried to re-occupy these areas but were defeated by Sultan Bayezid at Nikopolis in 1396 AD. This battle stabilized the Ottoman occupation in the area for the coming centuries, until the Balkan wars at the beginning of the 20th century. At the end of the 13th century, the Habsburg dynasty appeared for the first time in the Upper Danube valley after they had lost their stronghold in 1291 AD to the Swiss Federation. Until the 15th century, the Habsburg influence was restricted roughly to the area of present Austria. After the successful battle against the Ottomans in 1683 at Vienna, the Austrians, together with their allies, expanded their territories, re-occupied Budapest, freed Hungary and for a short period also Belgrade. The fight for the ‘golden apple’ Vienna was a historic benchmark event for all of Europe. Kara Mustafa moved 200 000 men, the largest army Europe ever saw, along the Danube, devastating whole areas. During these battles, galleys constructed by the Dutch were successfully used on the Danube. In 1867, the Austrio-Hungarian Monarchy was formed, which was known as the ‘DanubeMonarchy’ until the great political reconfiguration in 1918. Along the Lower Danube and delta, the Russians established their influence at the beginning of the 19th century. After World War II, the Iron Curtain again divided the Danube basin and increased the difference between the two parts. The Danube has served as a major waterway since the Greek period. In Vienna, the Romans already erected a pontoon bridge during the war against the Markomans. And at Drobeta Turnu–Severin (Serbian/Romanian border), the Emperor Trajan erected in 105 AD a 1000-m wide wooden bridge across the Danube (the famous Trajan bridge). The Tabula Trajana, a monument of the Roman frontier, marks a section of the Roman road along the Danube. The tablet honours Trajan for the construction of the road and bridge over the Danube. Along the Pannonian section of the Danube, the Classis Pannonica, the warship fleet of the Romans operated. These boats were 35-m long and 5-m wide, provided space for 120 people and reached a speed of 10 km/hr (Weithmann 2000; Landesausstellung 1994). In 1828, the ‘Donau-Dampfschiffahrtsgesellschaft’ (DDSG) was founded. It soon became the world’s largest inland shipping company, with a total length of navigable rivers and canals of 4100 km, a fleet of 1000 ships and 12 000 staff members. Early attempts to connect the Danube with the Main and Rhine Rivers date back to Charlemagne in 793, who tried to build a 2-km long canal between Altm€uhl and the Swabian Rezat, yet failed to complete it. In the following centuries, this idea was brought up several times but was never fully realised. The Bavarian King Ludwig I opened in 1845 a continuous waterway – the ‘Ludwig–Main–Danube–Canal’ – which was in operation until World War II, but never gained
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importance because of limited capacity and the concurrent development of the railway network. Construction of the 177-km long Rhine–Main–Danube Canal started in 1960 and was completed in 1992. Early attempts to coordinate the use of the Danube River led to the 1856 Treaty of Paris. Based on negotiations that started in 1848 (Congress of Vienna), the Budapest Commission was created to coordinate navigation. A convention on fisheries was signed among the lower Danube countries, but it took 2500 years after Herodotus and the fall of the Iron Curtain for Europeans to agree on the protection and sustainable use of the river. Based on the Danube River Protection Convention signed in 1994, the International Commission for the Protection of the Danube River (ICPDR) was founded.
3.3. PALAEOGEOGRAPHY AND GEOLOGY Comprehensive introductions to the palaeogeography and geology of the Danube River Basin are given in Liepolt (1967); Hantke (1993); Bl€ uhberger (1996); Neppel et al. (1999); Domokos et al. (2000); Belz et al. (2004) and Kovac et al. (2006). The largest part of the basin belongs to the alpidic or neo-European geological macro-region in Europe. Smaller parts belong to the western and eastern Variscan subregions and to the pre-Palaeozoic Russian platform. In the tertiary, the basin was part of the Paratethys, a branch of the Tethys, the proto-Mediterranean Sea. During this period, the Alps, the Carpathian Mountains, the Dinarides and the Balkan Mountains started to fold via plate tectonics. In the Miocene and Pliocene, the nuclei of these mountain chains formed islands in the shallow Paratethys. The rivers that exist today appeared for the first time in the Middle Miocene. They emerged as coastal rivers from the surrounding mainland and as streams on the Paratethys islands. It is worth noting that the basin boundary of the former Paratethys is almost identical to the present boundary of the Danube basin. Since that time, only local exchanges between neighbouring basins took place. During the Pliocene, a strong uplift of the mountains occurred. Subsequently, massive debris and sediment erosion, conditioned by a sub-tropical climate, gradually filled the shallow Paratethys. A progressive subsidence of subbasins, the Pannonian basin in particular, followed. At the end of the Pleistocene, the Paratethys became brackish, then freshened and finally formed a network of lakes, swamps and watercourses. This fluvio-lacustrine system disappeared when the residual lake Geta silted up completely in the first half of the Pleistocene. Periodic cooling during the Pleistocene led to partial and complete (in the Alps) glaciation of the mountains that continued to rise. As a consequence, physical weathering generated vast amounts of solid material that filled the Danube basins to their present level. In piedmont zones, the rivers formed megafans and bedload ramps and the channels
PART | I Rivers of Europe
permanently shifted their course. In glaciation-free mountains, the rivers followed incised valleys. Geologically, the Upper Danube is much older than the Rhine. In the Pleistocene, the Rhine started at the southwestern tip of the Black Forest, while waters from the Alps that today feed the Rhine were carried east by the so-called Urdonau (original Danube). Parts of this ancient riverbed, which was much larger than the present Danube at this location, can still be found as submerged canyons in the Swabian Alb. After the Upper Rhine valley had descended, rivers draining the northern slopes of the Alps changed their direction towards the Rhine. Because the Swabian Alb consists of porous limestone and the valley bottom of the Rhine is much lower than the Upper Danube, water from the Danube still continues to feed the Rhine via subsurface pathways (the so-called ‘Donauversickerung’ or ‘loss of Danube’ near Immendingen). Most of this water resurfaces at Aachtopf, Germany’s most yielding spring with an average production of 8000 L/s, north of Lake Constance. In the Middle Danube, following the aggradation of the Vienna Basin, the river first followed the eastern margin of the Alps southwards, turned at the southern border of the Pannonian Basin eastwards, and finally reached the Iron Gate. At Visegrad Gate, it formed an immense alluvial fan that gradually filled the depression of the Great Hungarian Plain. In the Lower Danube, the river course is more stable. Due to climate-induced low flow, tributaries exiting the mountains immediately deposited coarse bedload material and only small amounts of sediments, mainly as suspended material, reached the Danube valley. The Danube River valley, structured by several terraces, stretched along the southern margin of the Romanian Lowland. During the past 15 000 years, the Romanian section of the Danube valley has been mainly shaped by tectonic activities. Between Bazias and Drobeta Turnu Severin, the Danube flows for 130 km through a deep valley that links the Pannonian depression with the Dacic Basin (‘Iron Gate’). The ongoing uplift of the Carpathian Mountains during the Pleistocene and Holocene resulted in intense erosion of the valley, which is 1500 m asl (cited in Belz et al. 2004). Average peak precipitation occurs in July in the western part of the basin, in May/June in the southeastern parts, and in autumn in the areas influenced by the Mediterranean. The highest average annual temperature (+11 to +12 C) occurs in the Middle and Lower Danube and in the lower Sava valley. Seasonal differences increase from west to east. In the Hungarian plains, the seasonal change in temperature (min./max.) can be as high as 74 C. Spatial and seasonal differences in precipitation have strong effects on the surface run-off and discharge regime of the Danube and its main tributaries (ICPDR 2005). For example, Austria (22% of total flow) and Romania (18%) contribute most to the total flow of the Danube, reflecting the high pecipitation in the Alps and Carpathian mountains. The average annual specific discharge decreases from 25 to 35 L/s/km2 in the Alpine headwaters to 19 L/s/km2 for the Sava, 6.3 L/s/km2 for the Tisza and to 2.8 L/s/km2 for the rivers draining the eastern slopes of the Carpathians (Belz et al. 2004). At its mouth at Ceatal Izmail (upstream end of the Danube delta), the mean annual discharge is 6480 m3/s, corresponding to an annual flow of 203.7 km3 (range: 134 km3 in 1990; 297.1 km3 in 1941) (Table 3.2).
In the Lower Danube, the flow regime has been modified by the Iron Gate dams as well as by the large water management schemes along the Olt, Arge¸s, Siret and Prut Rivers. The suspended sediment load decreased from 40 million tons/year (maximum of 106 million tons in 1940) to a low of 7.3 million tons/year today. The basin has experienced many disastrous floods. The flood in February 1342, associated with a big ice drift, caused the reported death of 6000 people. The largest flood during the past millenium was the memorable flood in August 1501. Peak discharge at Vienna was 14 000 m3/s, and flood marks can still be seen along the entire Danube. Since 1821, the water level has continuously been recorded at selected stations. The flood in 1862 stimulated the regulation of the main Danube (1869 to 1876, see Photo 3.4a, b and c), and the largest flood in the last century occured in 1954 (peak discharge at Vienna was 9600 m3/s).
3.6. BIOGEOCHEMISTRY, WATER QUALITY AND NUTRIENTS 3.6.1. General Characteristics Physico-chemical and selected biological parameters are regularly monitored by the International Commission for the Protection of the Danube River (ICPDR). These data for the Danube and its main tributaries are mostly derived from the TransNational Monitoring Network (TNMN; monitoring period: 1996–2005). The biogeochemistry of the Upper Danube is mainly influenced by the Alps. The major tributaries Sava, Drava and Tisza dominate the chemistry of the Middle Danube, where alluvial deposits predominate,
TABLE 3.2 Flow regime (in m3/s) of the Danube River and its tributaries (time period: 1931–1990) River
Station
A (km2)
NQ
MNQ
MQ
MHQ
HQ
MHQ/MNQ
Danube Danube Danube Danube Danube Danube Inn Morava V ah Drava Tisza Sava Velika Morava Olt Siret Prut
Berg Regensburg Vienna Bezdan Orsova Ceatal Izmail Passau-Ingling Moravsky Jan Sala Donij Miholjac Senta Sremska Mitrovica Ljubicevski Most Stoenesti Lungoci Cernicvi
4047 35 399 101 731 210 250 576 232 807 000 26 084 24 129 10 620 37 142 141 715 87 996 37 320 22 683 36 036 6890
4.6 107 504 505 1060 1790 195 7.7 0.5 166 80 194 17 15 16 1.5
12.9 198 832 992 2246 2901 267 29 22 234 179 401 55 48 52 10
38.5 444 1920 2372 5611 6486 732 110 138 541 792 1572 277 172 210 67
209 1468 5547 4788 10 604 10 889 2936 584 861 1359 2142 4154 1290 908 1294 1200
445 2531 9600 7689 14 813 15 540 6359 1573 1497 2281 3730 6638 2355 2320 2825 2170
16.2 7.4 5.5 4.8 4.7 3.8 11.0 20.1 39.1 5.8 12.0 10.4 23.5 18.9 24.9 120
A: Catchment area upstream of gauging station. NQ: lowest measured discharge. MNQ: arithmetic mean of the lowest measured annual discharge. MQ: arithmetic mean annual discharge. MHQ: arithmetic mean annual flood discharge. HQ: highest measured discharge (data: Belz et al. 2004).
Chapter | 3 The Danube River Basin
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PHOTO 3.4 The Danube River at Vienna in 1848, 1888 and 1989 (from Mohilla & Michlmayr 1996; with kind permission from Oesterreichischer Kunst und Kulturverlag, Vienna).
whereas the Iron Gate reservoirs influence the biogeochemistry and material transport in the Lower Danube (Garnier et al. 2002; Teodoru & Wehrli 2005). Last, the flux of nutrients and transported material to the Black Sea is influenced by the Danube delta, one of the largest European wetlands and covered by vast reed beds (UNESCO-MAB Biosphere Reserves Directory – www.unesco.org). In general, the ion content increases along the course of the river. Calcium is the major cation, and carbonates, sulphates and chlorides are the main anions. Tributaries with the highest ion contents include the Prut and Siret, where elevated conductivity values result from high sulphate and chloride concentrations (Table 3.3). Suspended solid concentrations increase with drainage size and range
from 27 mg/L to over 40 mg/L. Suspended solid concentrations are positively related to discharge with maximum concentrations during the rising limb of the hydrograph that can exceed 1000 mg/L (Zessner et al. 2005). The Siret and Prut as well as the Inn and Tisza Rivers exhibit the highest mean concentrations of suspended solids. In the Austrian Danube section, suspended solids are dominated by silt (70%) and clay (25%), mainly composed of silicates and secondary limestones of Alpine origin (Nachtnebel et al. 1998). The discharge-weighted annual load of suspended solids ranges from 0.7 to 3.1 106 t/year in the Upper Danube and from 3.5 to 6.3 106 t/year in the Lower Danube (TNMN yearbook 2000–2004). The Inn and Tisza contribute most to the annual load of the river
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TABLE 3.3 Physicochemical and biological parameters of the main Danube River sections and tributaries based on data from the TransNational Monitoring Network (TNMN) 1996–2005 Organic Ammonium Nitrate Nitrite Total Orthophos- Silicates Calcium Chloride Magnesium Sulphate Suspended TOC DOC Chlorophyll BOD(5) Total (SiO2) nitrogen nitrogen (NH4–N) (mg/L) (mg/L) a (mg/L) (NO3–N) (NO2–N) phosphorus phate (Ca2+) (Cl ) (Mg2+) (SO4 ) solids (mg/L) (mg/L) (mg/L) (PO4–P) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Upper Min. Danube Mean Max. n
247 386 641 1489
3.7 10.9 28.0 1501
7.5 8.2 9.0 1490
1.0 2.6 5.2 293