Protecting the Gulf's Marine Ecosystems from Pollution

UNESCO DOHA OFFICE

NCWCD

Ruprecht-Karls Universität Heidelberg

Protecting the Gulf’s Marine Ecosystems from Pollution Abdulaziz H. Abuzinada Hans-Jörg Barth Friedhelm Krupp Benno Böer Thabit Zahran Al Abdessalaam Editors

Birkhäuser Basel · Boston · Berlin

Abdulaziz H. Abuzinada Khaled Bin Sultan Living Oceans Foundation P.O. Box 69428 Riyadh 11547 Kingdom of Saudi Arabia Friedhelm Krupp Senckenberg Research Institute and National History Museum Senckenberganlage 25 60325 Frankfurt a.M. Germany Thabit Zahran Al Abdessalaam Marine Environment Research Centre Environmental Agency – Abu Dhabi (EAD) P.O. Box 45553 Abu Dhabi United Arab Emirates

Hans-Jörg Barth Department of Geography Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 348 69120 Heidelberg Germany Benno Böer UNESCO Doha 66 Lusail Street – West Bay P.O. Box 3945 Doha, Qatar

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e-ISBN 978-3-7643-7947-6

987654321

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Contents

List of contributors……………………………………………………

VII

Editorial……………………………………………………………….

IX

Preface by H.R.H. Prince Turki Bin Naser Bin Abdulaziz ...…………

XI

Foreword by Walter Erdelen, UNESCO ……………………………...

XIII

Foreword by Yousef Omair bin Yousef, CEO, ADNOC…………………

XV

H.-J. Barth and N.Y. Khan Biogeophysical setting of the Gulf ...…………………………………

1

G. Brown, B. Böer, S. Sakkir The coastal vegetation of the western and southern Gulf characterisation and conservation aspects ..……………………….….

23

F. Krupp and A.H. Abuzinada Impact of oil pollution and increased sea surface temperatures on marine ecosystems and biota in the Gulf ……………………………..

45

N.Y. Khan Integrated management of pollution stress in the Gulf ……………….

57

H.N. El-Habr and M. Hutchinson Efforts of regional and international organisations in reducing levels of pollution in the Gulf …………………………………………

93

A.M.M. Al-Janahi Oil pollution preparedness in the ROPME Sea Area …………………

107

R.A. Loughland and B. Saji Remote Sensing: A tool for managing marine pollution in the Gulf …………………………………….………………….……

131

VI

Contents

K. Zainal, H. Al-Sayed and I. Al-Madany Coastal pollution in Bahrain and its management ……………………..

147

R. Facey Pollution from sea based sources ……………………………….……..

163

S. Lattemann and T. Höpner Impacts of seawater desalination plants on the marine environment of the Gulf .………………………………………………

191

F. Al-Yamani Importance of the freshwater influx from the Shatt-Al-Arab River on the Arabian Gulf marine environment .……………………...

207

S.M. Al-Ghais and W.H. Pearson The compensation schedule approach for the assessment of oil spill damages to marine resources of the RSA .…………………………….

223

D.A. Jones, M. Hayes, F. Krupp, G. Sabatini, I. Watt and L. Weishar The impact of the Gulf War (1990 – 91) oil release upon the intertidal Gulf coast line of Saudi Arabia and subsequent recovery ….

237

H.-J. Barth Rapid assessment indicators of oil spill recovery in salt marsh ecosystems ………………………………………………….…............

255

T. Höpner and K.A. Al-Shaikh Shoreline bioremediation after the 1991 Gulf War oil spill ………….

265

L. Weishar, I. Watt, D.A. Jones and D. Aubrey Evaluation of arid salt marsh restoration techniques ………………….

273

Abbreviations ………………………………………………………….

281

Index …………………………………………………………………..

283

List of contributors

Abuzinada, Abdulaziz H., Board Member - Special Advisor, Khaled Bin Sultan Living Oceans Foundation, P.O. Box 69428, Riyadh 11547, Kingdom of Saudi Arabia; e-mail: [email protected] Al Abdessalaam, Thabit Zahran, Director, Marine Environment Research Centre, Environmental Agency-Abu Dhabi (EAD), P.O. Box 45553, United Arab Emirates. Al-Ghais, Saif M., Biology Department, Faculty of Science, UAE University, AlAin, P.O. Box 17551, United Arab Emirates; e-mail: [email protected] Al-Janahi, Abdul Munem Mohamed, Marine Emergency Mutual Aid Centre (MEMAC), P.O. Box 10112, Kingdom of Bahrain; e-mail: [email protected] Al-Madany, Ismail, Public Commission for the Protection of Marine Resources, Environment and Wildlife, P.O. Box 32657, Manama, Kingdom of Bahrain; e-mail: [email protected] Al-Sayed, Hashim, Biology Department, University of Bahrain, P.O. Box 32038, Kingdom of Bahrain; e-mail: [email protected] Al-Shaikh, Khalid Ali, Jubail Marine Wildlife Sanctuary, National Commission for Wildlife Conservation and Development (NCWCD), P.O. Box 61681, Riyadh 11575, Kingdom of Saudi Arabia Al-Yamani, Faiza, Kuwait Institute for Scientific Research, P.O. Box 1638, Salmiyah-22017, Kuwait; e-mail: [email protected] Aubrey, David, Woods Hole Group, 81 Technology Park Drive, East Falmouth, MA 02536, USA Barth, Hans-Jörg, Department of Geography, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 348, D-69120, Germany; e-mail: [email protected] Böer, Benno, UNESCO, Doha, 66 Lusail Street - West Bay, P.O. Box 3945, Doha, Qatar; e-mail: [email protected] Brown, Gary, Kuwait Institute for Scientific Research, AAD, P.O. Box 24885, Safat 13109, Kuwait; e-mail: [email protected] El-Habr, Habib N., Director and Regional Representative UNEP Regional Office for West Asia, P.O. Box 10880, Manama, Kingdom of Bahrain; e-mail: [email protected] Facey, Roy, Port Development Adviser, Yemen Gulf of Aden Ports Corporation, Aden, Republic of Yemen, e-mail: [email protected]

VIII

List of contributors

Hayes, Miles, Panion Ltd, 1119 Park Street, Columbia, Sc. 29202; e.mail: [email protected] Höpner, Thomas, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky Universitaet Oldenburg, Carl-von-OssietzkyStr. 9-11, P.O. Box 2503, D-26111 Oldenburg, Germany; e-mail: [email protected] Hutchinson, Melanie, Associate Programme Officer, UNEP Regional Office for West Asia, P.O. Box 10880, Manama, Bahrain; e-mail: [email protected] Jones, David Alan, P.O. Box No: 443, Ctra. Cabo La Nao (Pla) 124-6, 03730 Javea, Alicante, Spain; e.mail: [email protected] Khan, Nuzrat Yar, Sustainable Development Study Centre, Government College University, Lahore, Pakistan, e-mail: [email protected] Krupp, Friedhelm, Senckenberg Research Institute and Natural History Museum, Frankfurt a.M., Germany; e-mail: [email protected] Lattemann, Sabine, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky Universitaet Oldenburg, Carl-vonOssietzky-Str. 9-11, P.O. Box 2503, D-26111 Oldenburg, Germany; e-mail: [email protected] Loughland, Ronald, A., Centre of Environmental Research, Emirates Heritage Club, P.O. Box 108444, Abu Dhabi, United Arab Emirates; e-mail: [email protected] Pearson, Walter, Environment Agency Abu Dhabi, P.O. Box 45553, Abu Dhabi, (formerly ERWDA), United Arab Emirates Sabatini, Gino, GS Consultants, 7054 D´Ibervillle,Montreal,Canada H2E 2Y4; e-mail: [email protected] Saji, Baby, Wataniya Environmental Services Co., Dar Al-Awadi Complex, Sharq, P.O. Box 27781 safat, 13135 Kuwait; e-mail: [email protected] Sakkir, Sabitha, Environment Agency Abu Dhabi, P.O. Box 45553, Abu Dhabi, United Arab Emirates Watt, Iain, IOMEC, Nelson Road, Grand Gaube, Mauritius; e-mail: [email protected] Weishar, Lee, Woods Hole Group, 81 Technology Park Drive, East Falmouth, MA 02536, USA; [email protected] Zainal, Khadija, University of Bahrain, Biology Department, P.O. Box 32038, Kingdom of Bahrain; e-mail: [email protected]

Editorial

In recent decades, and especially during the last few years, coastal development in the Gulf countries accelerated tremendously due to significant increase in oil related income and economic diversification strategies. Rapid expansion of industrial complexes, exceptional increase in private real estate investment, tourism and service industries, high birth rates and influx of foreign labour, accompanied by prospering economies, resulted in an enormous human population growth in the Gulf’s coastal areas. This development does much to further the well-being of the people and it also leaves severe impacts on the terrestrial, coastal and marine environment. These have changed - and not always for the better. Large areas of the coastal zone including important marine habitats are currently threatened by increasing stress on the Gulf ecosystem, and pollution plays a major role. However, it is exactly this ecosystem that people depend upon directly and indirectly. It serves as resources for fishing, recreation, urban development and probably most importantly, as a major source of freshwater via desalination plants. Although public awareness of environmental issues has grown significantly during the last few years, the scientific information base currently available is inadequate. Informed decision making on resource use, regional planning and adequate environmental impact assessment procedures need scientific documentation and analysis of the different types of pollution and their effects on the coastal and marine environment. It is essential to generate knowledge and technologies on how to prevent and minimize adverse impacts based on the different types of pollution. The first comprehensive monograph, which addressed the ecosystem health and sustainability of the Gulf (Khan et al. 2002), was sponsored by the Kuwait Institute for Scientific Research (KISR) and published by the Aquatic Ecosystem Health and Management Society (AEHMS) in 2002. Following this landmark publication, several international workshops were held in 2005 in Abu Dhabi and Dubai to look into issues of coastal zone management. In a next step the United Arab Emirates University together with AEHMS organized the first international conference on “The State of the Gulf Ecosystem: Future and Threats”, which was held in Al Ain in March 2006 and focused on the problems confronting the Gulf ecosystem and environmental management. The growing attention of the scientific community towards the coastal and marine resources of the Gulf is reflected by the participation of leading environmental experts from 29 countries. A selection of the papers presented at this conference has recently been published in “Aquatic Ecosystem Health & Management“.

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Editorial

Apart from these efforts, a shared vision of a healthy and sustainably managed Gulf ecosystem is still lacking in most of the coastal states. Since both pollution and biota transcend political boundaries, an integrated management of pollution stress on a Gulf-wide basis is an imperative for the Gulf nations. This is a very difficult task which lies ahead of us and with this in mind, UNESCO decided to produce this science-based book on pollution management in the Gulf. The Abu Dhabi National Oil Company (ADNOC) generously sponsored this project which was carried out in cooperation with the National Commission for Wildlife Conservation and Development (NCWCD), Riyadh, Saudi Arabia. The contributions of 28 authors aim at locating the gaps and obstacles, which are currently preventing an effective, transboundary management of the marine and coastal resources and present recommendations of how to improve the situation. This multidisciplinary book on pollution and its mitigation in the Gulf could not have been completed, without the enthusiastic participation of the experts authoring the various chapters. We therefore offer our sincere thanks to all the ladies and gentlemen, listed as authors of this book. We wish to express our gratitude to the referees who, with their expertise helped to improve the manuscripts. We also thank the Birkhäuser Verlag for their support, flexibility and professional way of handling the publishing process. Special thanks are due to Dr. Hans Detlef Klüber and Karin Neidhart. Finally it gives us great pleasure to express our thanks to ADNOC for their partnership, essential for the publication of this book. We trust that this volume will prove useful to scientists, students, environmental managers and decision makers in understanding the urgent need of “Protecting the Gulf’s marine ecosystems from pollution”.

The Editors

Preface

The countries of the Arabian Peninsula have undergone a remarkable process of development and social transformation. This has led to increased rates of transport, industrial development, and consumption of water, food, and goods, which in turn, led to significantly increased rates of environmental pollution. Regional conflicts have also taken their toll and contributed to environmental pollution. For example, the 1991 Gulf War Oil Spill, the biggest known marine pollution event in human history, has occurred in the waters of the Gulf. Moreover, the Gulf is the busiest area in the world in view of maritime oil shipment, and one of the undesired consequences are frequently occurring oil spills, and their impacts on the marine and coastal ecosystems, as well as on the fishing and tourism industry. Wind often blows land-based rubbish towards the sea, and it normally accumulates in the inter-tidal zone; driftwood on the ocean’s surface, as well as all floating trash also eventually accumulates in the coastal zone. This has led for some beaches in the Gulf to be heavily polluted with garbage. Such a development is not only unsightly, but also prevents certain marine organisms, such as turtles, for example, from landing on the beach. It also contributes for waterfowl and other creatures to get entangled in plastic snares and ropes, and exposes them to a slow and painful death: starvation. The situation under the water surface is not much better: environmentally concerned divers routinely clean the sea-bottom from rubbish and ghost-nets, often with dead marine organisms entangled in them, such as dugong, dolphin, whale, turtle and fish. Since decades the environmental groups are organising beach clean up campaigns, as well as dive-clean-up campaigns. Then there is chemical pollution affecting salt marshes and mangroves, coral reef and seagrass-beds as well as other ecosystems. The waters adjacent to the numerous desalinisation plants are exposed to thermal pollution and an increase in seawater salinity levels, even if locally confined. Additionally there is obvious air pollution, and a number of different other types of pollution. Even nuclear pollution of marine sediments has been reported. The people of Arabia depend on and care for the coastal and marine ecosystems, as an integral part of their heritage, and it is also an important source of fish, and seafood. Seawater as an absolutely essential raw material for human living, since it provides most of the region’s drinking and industrial water via desalinization plants. It cannot be underlined enough just how important the marine ecosystems are in view of freshwater security, food security, transport and

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Preface

recreation, and that we have got to manage them at the highest possible professional level, and keep them intact. Due to the wisdom of several of the region’s political leaders, environmental research, education, legislation, and conservation bodies were established in the region, in order to combat adverse environmental impacts, and to try and guarantee the conservation and sustainable development of the country's natural heritage. However, the current rate of pollution seems to be a challenge. A concerted cross-border action is required, together with the necessary legislation, and an implementation strategy. It is UNESCO who has initiated a process of bringing together the riparian countries in the Gulf in order to jointly address and discuss cross-border environmental coastal and marine issues. The process is being supported by UNEP and ROPME, and it is slow but steady ongoing, and it will include dealing with pollution. This volume is a comprehensive introduction towards the understanding of coastal and marine pollution in the Gulf. It will inspire the reader, whether on the researcher level, the layman level, the level of the decision maker and politician, or the level of the industrial developer, towards the initiation and the enhancement of ecosystem management practices in view of pollution. We are certain that this scholarly work is a meaningful contribution documenting the numerous pollutionrelated problems, and that it offers guidance on how to minimize adverse impacts and how to keep our environments clean. We also hope that environmental managers will be inspired and keep working even harder to combating coastal and marine pollution in the best interest of the people living in the Gulf. We thank the UNESCO Doha Office in Qatar for their initiative, we thank the Abu Dhabi National Oil Company ADNOC in the United Arab Emirates for their commitment and support, and we also thank the Saudi Arabian National Commission for Wildlife Conservation and Development for their leading role in producing this publication. Furthermore we convey our sincere respects and thanks to the editor’s and the experts for their enthusiastic and professional work that led to the production of this highly valuable contribution, which we warmly welcome.

HRH Prince Turki Bin Naser Bin Abdulaziz, President, PME Chairman, Council of the Arab Ministers of Environment

Foreword

Protecting the Gulf’s Marine Ecosystems from Pollution has been produced in cooperation between the National Commission of Wildlife Conservation and Development of the Kingdom of Saudi Arabia and UNESCO, with support from the Abu Dhabi National Oil Company. Sustainable living in the Gulf is dependent upon resources provided by the sea. Marine and coastal ecosystems are essential for the continuous supply of freshwater, seafood and for other ecosystem services. However, some of the world’s largest landfill and dredging projects are found in the coastal areas of the Gulf, and the open sea contains the world’s main crude oil shipping routes. Marine pollution, therefore, is one of the undesired factors that accompanies this development. A variety of human impacts are contributing to marine pollution, such as oil, sediments, waste, thermal, chemical, noise, and other forms of pollution. Oil spills are of major concern, and more recently, as mentioned, coastal dredging and landfill. In the long term, systems that provide primary productivity, such as seagrass beds, macro-algal reefs, phytoplankton communities, mangrove forests, salt marshes, cyanobacterial mats, and coral reef communities are crucial for the functioning of the marine ecosystems in the Gulf. Even more important, the seawater is of direct concern for freshwater security, because most of the drinking water for people comes from the sea, in an area with the highest density of desalinization plants in the world. Scientific research into the natural ecosystems will be very important in order to have the necessary knowledge base to enable us to carry out coastal and marine engineering projects with limited adverse environmental impacts. It will also be particularly useful in decision-making for addressing any form of marine pollution, with a special view to food and water security. Even though the regional organizations ROPME and MEMAC, intergovernmental organizations such as UNESCO, UNEP, and IMO, national environmental agencies, ministries, authorities, universities, a number of NGOs, as well as health, safety, and environment departments of private sector companies, are dealing with the subject of combating marine pollution, the science-based management of ecosystems and the maintenance of intact ecosystems and clean water are very difficult tasks that lie ahead. It is with this in mind that UNESCO decided to pursue the request of the National Commissions for Education, Science, and Culture of the Kingdom of Bahrain, the State of Kuwait, the Sultanate of Oman, the State of Qatar, the

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Foreword

Kingdom of Saudi Arabia, and the United Arab Emirates, to produce a sciencebased book on pollution management. I express my sincere thanks to the Abu Dhabi National Oil Company for their generous sponsorship, and to the National Commission for Wildlife Conservation and Development in Saudi Arabia for their cooperation. I congratulate the authors and editors of this new scientific volume for their important contribution to combating marine pollution, which I am sure will be warmly welcomed. Walter Erdelen Assistant Director-General, Natural Sciences Sector, UNESCO

Foreword

It is my honor to present to you the new science-based publication “Protecting the Gulf’s Marine Ecosystems from Pollution”, coordinated by the National Commission of Wildlife Conservation and Development NCWCD, Riyadh, in conjunction with UNESCO, supported by the Abu Dhabi National Oil Company ADNOC. The project was initiated by UNESCO Doha, based on suggestions from the UNESCO National Commissions in the Gulf. The coastal areas in the Gulf are rapidly developing, with some major coastal engineering projects emerging. The development has positive, and also negative aspects, and marine pollution is one of them. Sustainable human development depends on the efficiency and ability to provide reliable information, based on environmental data and human activities. Therefore it is advisable to keep abreast of progress in environmental sciences, environmental education, and social transformation. It is essential to scientifically document and analyse the different types of pollution and their effects on the environment, and to generate knowledge and technologies on how to prevent and minimize adverse impacts based on pollution. The marine and coastal zones are an integral part of the natural and cultural heritage of the maritime countries in the Gulf. Extensive inter tidal and marine ecosystems exist here, with a broad variety of habitats and biological diversity. In the past, today, and in the future, the people here depend on the marine and coastal resources. In a functionary sense the ecosystems via desalinization plants, provide drinking water for the local inhabitants, and as well serve as areas for recreation, fishing, urban development, and transport. These resources are essential for the continuous supply of freshwater, fish, crustaceans, for marine primary productivity, and for ecosystem functioning. Therefore, the marine and coastal resources have to be dealt with the greatest care and sensitivity. Together we have to try and continuously guarantee maximum benefit for the human population, based on intact and healthy environment. The benefits include the protection of the human population from environmentally caused diseases, as well as the development of environment-based jobs and income. ADNOC is fully aware of the importance of the ecosystems biotic and abiotic components, and it is with this in mind that ADNOC decided to support this book publication “Protecting the Gulf’s Marine Ecosystems from Pollution”. The reader will learn from the articles in this publication, about the existing threats of pollution that exist in the region, and methods of pollution management. Improving the knowledge of environmental managers, researchers, administrators,

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Foreword

and decision makers, will contribute towards improvement of environmental management in the Gulf. We congratulate the authors for their excellent work, and we hope it will inspire the environmental agencies and stakeholders in the region to continuously work together towards professional environmental management. Finally we thank the NCWCD and the UNESCO Regional Office in the Arab States of the Gulf for initiating this activity, and for their professional partnership, and we thank the Environment Agency - Abu Dhabi, the University of Heidelberg and the Senckenberg Research Institute for logistic support, and last not least the authors for their excellent contributions. Yousef Omair bin Yousef Secretary General of the Supreme Petroleum Council Chief Executive Officer of Abu Dhabi National Oil Company (ADNOC).

Protecting the Gulf’s Marine Ecosystems from Pollution Edited by A.H. Abuzinada, H.-J. Barth, F. Krupp, B. Böer and T.Z. Al Abdessalaam © 2008 Birkhäuser Verlag/Switzerland

Biogeophysical setting of the Gulf Hans-Jörg Barth1 and Nuzrat Yar Khan2 1 2

Department of Geography, Heidelberg University, Germany Sustainable Development Study Centre, Government College University, Lahore, Pakistan

The Gulf is a semi-enclosed sea (total area 240,000 km2) situated in the subtropical high-pressure-zone and thus characterized by low precipitation and high aridity, resulting in evaporation rates above 2000 mm yr-1 (Barth 1998). It is a shallow sedimentary basin, about 1000 km long and between 200 and 330 km wide. The average depth is presently 35 m with a generally eastward dipping seafloor. The deepest areas are in front of the Iranian coast, reaching from 60 m to about 100 m at the entrance to the Strait of Hormuz. Thus, the whole Gulf lies within the photic zone. The shoreline at the Arabian side displays a gradual slope with a wide intertidal zone, compared to the steep and narrow shoreline at the Iranian side where the Zagros mountains rise more than 2000 m. As a consequence of the gradual topography and of the favourable environment to carbonate producing biota, the Gulf is a strongly sedimentary province with a dominating soft substrate benthos. Sediments of biogenic carbonates - mostly foraminifera - exist over much of the Gulf floor (Sheppard et al. 1992). Highest carbonate concentrations are to be found in the shallow waters of the western and southern Gulf (Fig. 1). Within a depositional setting along the southern Gulf coast the offshore bank is progressively extending (Kendall et al. 2002). Terrestrial sediments are limited to the northwest where the waterway of the Shatt al Arab discharges into the Gulf, and the eastern Iranian shoreline where terrestrial fluvial sediments from the Zagros mountains occasionally are accumulated in the nearshore region. Offshore, underlying salt domes have forced upwards numerous islands and banks of hard substrate which are now colonized by corals.

2

Hans-Jörg Barth and Nuzrat Yar Khan

Figure 1. Carbonate content of surface sediments in the Gulf (modified after Sheppard et al. 1992).

Geology of the Gulf region The geologic situation of the Gulf region is basically the result of continuous sediment accumulation since Paleozoic times. The present structure was established during major tectonic processes in the Tertiary period. The Arabian Peninsula originally was attached to the African (Nubian) Shield. At the beginning of the Cambrian to the north and the east of the Arabian Peninsula a great sedimentary basin (Tethys) had developed. Throughout the Paleozoic, Mesozoic, and early Cenozoic times sediments accumulated in this slowly sinking trough. In the wide epicontinental seas between the Tethys and the Arabian Peninsula, a relatively thin succession of almost flat lying Paleozoic, Mesozoic, and early Cenozoic strata was deposited (Chapman 1978). These strata spread widely over the eastern Arabian Peninsula. In the late Cretaceous, orogenic movements constituted the first stage of the Alpine orogeny. The second stage began in the late Tertiary, when the deformed rocks of the geosyncline started to rise, leading to the formation of the Taurus, the Zagros mountains, and the Oman mountains. The Arabian Peninsula itself was little affected by this uplift except for being tilted towards the eastern Gulf region. There subsidence continued. In the middle Tertiary (25 Ma ago), when these events were at progress, the Arabian plate started to split away from the African Shield along the large rift system

Biogeophysical setting of the Gulf

3

which extends from the Gulf of Aqaba and the Dead sea rift in the north to the Afar triangle in Ethiopia. There it diverges through the Gulf of Aden into the Arabian Sea and down the African mainland as the large African Rift Valley System in the south. The separated Arabian plate started moving northeastward with a slight counter-clockwise turn, sliding beneath the great Asian plate in Iran. The tensional forces along the rift lead to the formation of a graben structure (Red Sea depression) with a pronounced relief between the plateau and the floor of the rift. Magma rising up the faults covered large parts of the eastern Arabian Shield. This development continues until the present. The current Red Sea rift is estimated to be between 2 and 3 cm each year (Stanley 1994). Thus the Arabian Peninsula can be divided into two structural provinces. The Arabian Shield in the west is part of the Precambrian crustal plate, generally exposed except the parts which are covered by tertiary volcanic rock. The second structural province is the Arabian Shelf in the east which consists of the sedimentary sequences covering the plate.

The Arabian Shelf The Arabian Shelf lies to the east of the shield where it forms two thirds of the peninsula. Its foundation consists of the same Precambrian plate that makes up the shield. On top of this basement a series of continental and shallow water marine sediments accumulated, ranging from Cambrian to Pliocene age. These layers dip gently away from the shield into a number of deep basins (Chapman 1978). Thus the thickness of the sediment strata increases gradually from the west to the east where in the coastal lowlands 11,000 m are reached (Alsharhan and Nairn 1997). Beside the main Zagros Reverse Fault even 18,000 m of sediment has accumulated (Edgell 1996). Erosion exposed most of the sediments, forming a series of parallel strike escarpments facing westward, each capped with resistant limestone. These cuestas are exposed in a great curved belt along the eastern margin of the shield, reflecting the gently arched surface of the buried basement. Large parts of the basins in the southeast (Rub’al Khali), east (Gulf), and northeast (Nefud) are covered by quaternary sandy sediments. The Persian Gulf Basin is the largest basin with active salt tectonism in the world. The more than 900 km long Gulf is the present-day geosynclinal expression of the 2600 km long Persian Gulf Basin. The Persian Gulf Basin consists of a number of NW-SE trending, geotectonic units such as the Arabian Plattform and the zone of marginal troughs, including the Zagros Fold Belt, limited on the northeast by the Main Zagros Reverse Fault (Edgell 1996). The Basin is crossed by several N-S structures, expressed by the major Qatar-Kazerun lineament (Qatar Arch). These rejuvenated uplifts have existed for 650 Ma. The Halokinesis in the Gulf originates where major intersecting basement faults (e.g. the Qatar-Kazerun lineament) cut the buoyant salt beds of the different formations (Edgell 1996). Diapiric oil fields as a result of salt tectonism account for 60% of the recoverable oil reserves of the Persian Gulf Basin (Edgell 1996).

Hans-Jörg Barth and Nuzrat Yar Khan

4

3.2 cm/year

ARABIAN GULF 2 cm/year

RED SEA Quarternary

Rub’ al Khali

Tertiary volcanic rocks Miocene and Pliocene

Oligocene Palaeocene /Eocene Cretaceous Jurassic

2 cm/year

Triassic Palaeozoic Precambrian Precambrium

Figure 2. Geology of the Arabian Peninsula and tectonic movements (after Chapman 1978 and Johnson 1998).

The southern part of the Mesopotamian depression includes the Gulf and a narrow coastal strip of the Arabian Peninsula. This coastal strip is the Gulf coastal region. The elevation of the coastal region rises gradually inland at a rate of about one metre per kilometre. The coastline is irregular, low, and sandy and the water has many shoals, so that tidal changes cause the waterfront to shift back and forth up to several kilometres. Sabkhat (salt flats) are common all along the coast from Kuwait to the southern end of the Gulf (Barth 2002). On the Iranian side steep shores formed by the anticlinal fold structure from the foothills of the Zagros mountains are dominant, together with narrow bands of alluvial coastal lowlands.

Sea level changes Considerably lower sea levels and even complete evaporation of the Gulf occurred in the Pleistocene. The period between 110 ka BP and 30 ka BP was characterised by considerable sea level fluctuations within the range of 30 and 60 m below present sea level (Sheppard et al. 1992). These sea levels correspond to

Biogeophysical setting of the Gulf

5

the depths of major wadis, especially at the Read Sea coast. After 30 ka BP the sea level fell rapidly to a minimum at about 17 ka BP. The values provided by various authors range between 120 and 150 m below present sea level. This implies that the Gulf was completely dry during that period. At about 15 ka BP global surface temperatures increased, which lead to the Holocene transgression. The rise in sea level commenced about 14 ka BP and proceeded rapidly to near present levels at about 6.0 ka BP. This transgression was especially pronounced during periods at 12 ka, 11 ka, 9.5 ka, 8.5 ka, and 7.0 ka BP (Teller et al. 2000, Glennie 1998) (Fig. 3). The average horizontal transgression between 13 ka and 6.0 ka must have been 140 m yr-1, but during periods of intense sea level rise this distance increased to more than 1000 m (Teller et al. 2000). The transgression reached its maximum at about 6.0 ka BP. At that time the sea level was between 2.5 (Felber et al. 1978) and 3.5 m (Lambeck 1996) above the actual level.

Figure 3. Palaeogeographic map showing the Gulf during the post-glacial transgression (source: Barth 2001, Uchupi et al. 1999, Glennie 1998, Felber et al. 1978).

About the succeeding development there are different opinions. Felber et al. (1978) and Evans et al. (1969) state that the maximum sea level situation persisted for about 2,000 years before regression started gradually. Kassler (1973) and AlAsfour (1978) assert a considerable regression to two meters below the present sea level at 5,000 yr BP and a following transgression back to the 6,000 yr BPlevel at 4,000 yr BP. The later development was characterised by alternation of trans- and regression (Fig. 3). Evans et al. (1969), Felber (1978), and Hötzl et al.

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(1984) as well as more recent studies (Alsharhan et al. 1995) promote the idea of a more gradual regression starting at 4,000 yr BP and reaching today’s level at about 1,000 yr BP (Fig. 4).

5

0 years B.P. in 1000

0

present sea level

8

6

4

2

sea level in m

-5 -10 -15 -20 -25

Kassler, 1973 Al-Asfour, 1978 Felber et al., 1978

-30

Figure 4. Sea level changes of the Gulf during the last 8000 years (based on 14C-dates of calcareous shells)(Barth 2001).

But even later than 1,000 yr BP the coastal geography at the western and southern Gulf coast experienced significant changes. Seaward progradation of carbonate intertidal flats in the UAE amounts up to seven kilometres during the last 4,000 years (Kinsman 1964). Coastal marine sediments, found in a distance of more than two kilometres from the present intertidal zone north of Jubail (Saudi Arabia), provided 14C dates (of cyanobacteria) of 700 yr BP. This implies an average progradation of more than 3 m/year (Barth 2001). 14C dates of cyanobacteria by Evans et al. (1969) in the Abu Dhabi sabkha indicate an average progradation rate of one metre per year for the last 1,000 years. Evans (2002) points out that the recent cyanobacterial mats lie slightly higher than the remains of older mats further inland. This may be due to local tectonics or some change in coastal morphology and the rate of supply of sediment, but there is also the possibility that it reflects a slight sea level rise (Evans 2002). Studies carried out by Al-Mansi (1992) may indicate a minimal rise of sea level in the Gulf of 2-3.8 cm between Ras Tanura and Saffaniya in the time period from 1980 to 1991.

Biogeophysical setting of the Gulf

7

General climate pattern The climate of the Gulf region is a typical desert and semi-desert climate, characterized by high summer temperatures and aridity throughout the year, due to its geographical situation within the subtropical high pressure belt. Descending air is adiabatically warmed as it looses altitude and consequently dries. This leads to an almost complete dispersal of cloud and an absence of rain, except when this pattern is disturbed by incursions from outside. These occur in the winter months between October and April. Thus, in the northern parts of the Gulf, rain is almost exclusively confined to this period. In the summer season the “Trade Winds”, which are generally north-easterlies, become north to northwest winds as a result of locally dominant pressure patterns over the Gulf and the Asian land mass to the east. The surface circulation in the summer months is influenced by two pressure zones. First, the eastern north-African high pressure centre, which - because of its clockwise turn - leads to northern currents over the Gulf region. Second, the thermal continental low pressure cell over the Asian land mass that reaches from the Indian subcontinent into the Gulf. It provides - because of its anti-clockwise turn - a northerly current on its western flank (Fig. 5 a). The southernmost area of the Gulf as well as the Gulf of Oman may then receive precipitation from monsoonal currents originating in the Asian low pressure cell which attracts tropical air masses. Due to the southward shift of the global pressure belts in the winter months, atlantic cyclones breaking free from the sub-polar low pressure belt move eastward across the Mediterranean Sea and pass across the northern part of the Arabian Peninsula. These depressions are gradually dissipated as they move east or southeast across Arabia, and the probability of rain thus decreases to the southeast. South-eastern winds are the result of currents on the south-western flank of the continental Asian high pressure cell (Fig. 5 b). Precipitation in the northern Gulf region in not exclusively due to the influence of Mediterranean depressions. Recent studies by Barth and Steinkohl (2004) demonstrate that the formation of new low pressure centres in Iraq, west to the Zagros mountains is equally important. Thermal convection, as well as the influence of currents from Sudan and Ethiopia, are other significant precipitation sources.

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A Europe

India

Africa Arabia

Indian Ocean

B Europe

Africa

India

Arabia

Africa

Arabia

India

Indian Ocean

Figure 5. Pressure zones influencing the Arabian Peninsula in July (A) and January (B) after Breed et al. (1979). The low pressure trough above the Gulf in summer leads to strong northern and northwestern currents of the Shamal.

Biogeophysical setting of the Gulf

9

Hydrographical influences The marine environment of the Gulf along the Saudi Arabian shores is a unique ecosystem among the world’s oceans. Primary determining factors are its restricted water exchange with the Arabian Sea, its high evaporation and low fresh water input, and its isolation (Hunter 1983).

Salinity and circulation Due to the high evaporation rates (more than 2,000 mm yr-1) there is a net loss of water in the Gulf. This creates a density dependent estuarine reverse flow (Reynolds 2002, Meshal and Hassan 1986). Fresh sea water (from the Indian Ocean) enters the Gulf through the Strait of Hormuz at a salinity of 36.5-37 ppt and circulates in a general counter-clockwise direction with northward currents along the Iranian shores and southward currents along the Saudi Arabian shores. With increasing distance from the Strait of Hormuz there is a general decrease in nutrients and increase in salinity because of excess of evaporation over fresh sea water input (Fig. 6).

Figure 6. Salinity of the Gulf surface water (in ppt) and general surface water circulation pattern.

The velocity of this current along the Iranian coast is the highest but gradually decreases towards the northern part of the Gulf and becomes rather sluggish along

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the western and southern coasts. Because of its relative consistency, this density driven current probably plays an important role in sediment dispersion, sediment deposition, and pollutant removal out of the Gulf through the Strait of Hormuz. The northern part of the Gulf represents a low energy zone and the circulation in this part of the Gulf is largely wind driven in the south-easterly direction on both the Iranian and Arabian sides (Elshorbagy et al. 2006, Swift and Bower 2003, Johns et al. 2003, Reynolds 2002, 1993). In the northern Gulf the diluting influence of the Shatt al Arab at the northwest corner of the Gulf is evident throughout the year, but especially in winter when flow is greater (Sheppard et al. 1992). The dense saline water of the western Gulf (now 40 ppt) sinks towards the trough along the Iranian coast and is returned southward in greater depths. It exits the Gulf via the Strait of Hormuz as a deep water current, providing the driving force for the renewal of the Gulf water. In winter, temperature gradients increase the density flow, since water retained in the south cools more than the inflowing water. The total exchange rate of the Gulf water is estimated from 3-5 years (Sheppard et al. 1992). Going southward along the coast of Saudi Arabia, the salinity increases dramatically south from Al-Khobar where restricted water exchange in the Gulf of Salwah, due to the Peninsula of Qatar, promotes highly saline conditions (Fig. 6). Salinities range between 38-42 ppt in the region north of Al-Khobar and 52-59 ppt in the open waters of the Gulf of Salwah (KFUPM/RI 1988). Because salinity is a controlling factor for occurrence and abundance of organisms, the waters south of Al-Khobar display a less diverse plant and animal life (Coles and McCain 1989). Studies carried out by the KFUPM/RI (1988) showed, that salinity is the physical variable most highly correlated with changes in plankton abundance. Reef corals and many other major taxonomic groups are not found south of Tarut Bay, and the number of species and individuals of benthic infaunal organisms and zooplankton decrease significantly with increasing salinity (Cole and McCain 1989).

Tidal pattern In the Gulf, the tidal pattern is complex and does not correlate with the tides of the Indian Ocean, although they are driven to some extent by the tidal forces propagating through the Strait of Hormuz. There are two amphidromic points where tidal range is zero (and around which tidal waves rotate). One is off the northern Saudi Arabian coast and the second off the UAE coast. The tidal regime in the central part is complex and basically semi diurnal (tidal cycle over 12 hours so that, on successive days, high and low tides occur approximately one hour later). However, in some areas of the Gulf there is only one daily, or diurnal, tide (Fig. 7). Over most of the Gulf away from shore, tidal range is 700 tonnes), intermediate spills (between 7 and 700 tonnes) and small spills (