Mangroves in Egypt

TCP/EGY/0168 (A) REHABILITATION, CONSERVATION AND SUSTAINABLE UTILIZATION OF MANGROVES IN EGYPT EGYPT Awareness Material for the Mangroves of Egypt (Source Text) by Ahmad K. Hegazy Project Coordinator & FAO Consultant (Professor of Conservation and Applied Ecology, Department of Botany, Faculty of Science, Cairo University, Giza 12613, Egypt) MINISTRY OF AGRICULTURE & LAND RECLAMATION MINISTRY OF STATE FOR ENVIRONMENT FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Cairo, July 2003 Preamble This report is prepared in accordance to consultancy agreement with FAO office, Cairo. The duration of agreement from 1 May to 31 July 2003. This report is to be used as a source text for the preparation of awareness material for the project. The target audience cover wide range, including school and university students, and general public. The key message is to get the target audience knowledgeable of the nature, value and uses, threats and impacts, conservation, restoration and sustainable use of mangroves in Egypt. The awareness material includes posters and computer CD of fully explained short film and still shots on different aspects of mangrove ecosystems in Egypt. Mangroves in Egypt (1) History and Status (2) Mangrove Habitats and Adaptations (3) Environmental Aspects and Link to Food Web (4) Contemporary Value and Uses (5) Human Impacts and Threats (6) Biodiversity (7) Socio-economic Aspects (8) Conservation and Restoration (9) Management of Mangroves (10) Legislative and Institutional Framework (11) Regional Plan for Sustainable Use (12) Summary and Conclusions (13) References for Further Readings Acknowledgement (1) History and Status The word "mangrove" has been used to refer either to the constituent plants of tropical and subtropical intertidal and adjacent forest / vegetation communities or to the mangrove habitats / ecosystems itself. The word "mangal" has been used to refer to the community, leaving mangrove for the habitat or ecosystem and constituent species. Mangrove ecosystems are among the most productive and biologically diverse wetland ecosystems on Earth. Mangroves occur mainly in sheltered situations behind reef flats of fringing reefs, bays or creeks and khawrs in the lee of offshore islands, and on some offshore islands. Habitats are usually not subject to direct wave activities and strong sea currents. In Egypt, mangroves occupy many sites along the Red Sea shoreline inundated by the extremes of tides. Mangal vegetation, either true or associate (exclusive or nonexclusive) flourish in the habitats between land and sea. True mangal vegetation occurs only in the intertidal habitats and rarely elsewhere, while the mangal associates typically occur in a non-mangrove habitats such as salt marshes or lowland water swamps in the adjacent vegetation. They create a habitat for a rich community of other organisms and provide the energy base of the mangrove ecosystem. Historically, the origin of mangroves in the world was first developed in the carboniferous epoch about 360 to 286 million years ago (Ma) when the salt- tolerant gymnosperms and pteridophyta appeared. However the modern mangrove genera (27 genera) were developed along the late Creataceous c. 65 Ma. During the Palaeozoic period (600 Ma-200 Ma), the Red Sea was land. The Jurassic marine fossil deposits demonstrated that the sea margins had advanced significantly southwards by Middle of Jurrasic time (c. 160 Ma). At that time the Gulf of Suez and the Gebel El Galala el Bahariya region were submerged under the water surface. It is postulated that the origin of mangrove in the Red Sea can be "indigenous" or "exogenous". The earliest mangrove record reported from Egypt dating back to the upper Cretaceous in Bahariya Oasis formation (Cenomanian: 93.5-99.0 Ma), where environmental succession occurred along the low-energy coasts (Bahariya system), helped mangroves migrate to the active shore faces of the Red Sea at that time. The excavated mangrove samples were rhizoliths, leaf compressions and stem of tree fern mangrove known as Weichselia reticulata (syn: Paradoxopteris stromeri). These mangrove specimens were found mixed to the recently discovered extremely large Sauropod dinosaur, from Bahariya Oasis (c. 300 km south west Cairo at 28 º 20 ´ N). The indigenous origin of mangrove species demonstrates that mangroves in Red Sea may had developed by migration and adaptation of the Bahariya mangrove; which migrated from the low-energy coasts at Bahariya to the active open sea in Red Sea coasts. This migration probably occurred in early Miocene epoch (25.5 Ma). During Miocene the Red Sea basin was a gulf of the Tropical Palaeo-Mediterranean and had no direct connection to the Indian Ocean. The exogenous origin of mangroves in Late Miocene epoch (25.5 Ma) and up lifting of the Isthmus of Suez region, have led to the severing of the connection between Mediterranean and Red Sea. At the nearly same age Bab el Mandab began to open to the South as the Red Sea was the first time opened to the Indian Ocean led to the migration of the Indo-Pacific fauna and flora. Many Indo-Pacific species invaded the Red Sea may be among of them some of the mangrove species. There are no archaeological mangrove samples recovered from the "Dynastic era"- Dynasty 1 to 30. However, about 2000 years ago, Theophrastus reported that ancient Egyptians used seedling of Rhizophora mucronata in medicine as aphrodisiac. Around the same time of Theophrastus, Nearchus reported the occurrence of mangroves in the region. These reports are probably the first ever to be reported in the world literature. Mangroves in Roman-Byzantine period (400-900 AD) was mentioned by Abu Abbas En-nabty, who wrote that at this period, mangrove trees were extensively used for boats, fuel, houses, forts, posts, poles, leather tanning in addition to its medical use to treat sore mouth. The first intact archaeological findings of mangroves were dated back to 400-900 AD at Abu Sha’ar site, 20 km northern Hurghada 27º N, Red Sea coast. The site has previously identified incorrectly as Ptolemaic—early Roman port Moys Hormos. The fort was active during this period as port for the European merchants to India and Ethiopia through the Nile crossing the desert wadis to the Red Sea. It was also the main port for the African Christian Pilgrims to Palestine. The huge amounts of excavated Avicennia marina leaves, branches and charcoal material reflect the local origin of these remains. The fort poles, fences and doors were made of Avicennia marina woody trunks. Some of these trunks were 40 cm diameter which is equivalent to about 25 m3 canopy volume. This forest-like growth can be found now in the south of Abu Sha`ar. The feeble growth of the relict A. marina trees at Abu Sha’ar region still denoting the presence of this plant in the earlier times. Mangroves in Early Islamic era (1000-1300 AD) were neither archaeologically sampled nor excavated, however, it was reported that the Rhizophora mucronata bark was used for tanning, the wood used for furniture due to its resistance to the termites, and propagules used as aphrodisiac during this era. The present estimates of mangroves in Egypt indicate that there are approximately 5 km2 total areas along the Red Sea coast distributed over numerous small stands. It is represented by two plant species namely Avicennia marina and Rhizophora mucronata. (2) Mangrove Habitats and Adaptations Mangroves colonize waterlogged soil on a variety of substrata, including silty and clayey muds, calcareous muds and sands. They may colonize coastal coral reef rubble as well as cracks and hollows on rocky substrata. They colonize the main wadi deltas, where sediments have been brought by runoff rainwater or deposited by tidal currents. Mangrove soils are generally slightly acidic. Carbon dioxide arising from the decomposition of organic matter and from an aerobic respiration lowers the pH value. The anaerobic conditions help sulphate reducing bacteria produce hydrogen sulphide, reduction of carbon dioxide to methane as well as conversion of nitrates to gaseous nitrogen, where the emission of these gases gives mangrove soils their pungent odour, soft and anoxic conditions. Soils are usually characterized by permanently water logging, high salinity and low oxygen concentrations and mostly anaerobic conditions. The characteristic gray or black colour of mangrove soils is due to the reduction of ferric compounds (insoluble) to ferrous sulphides (soluble) where iron and phosphates released into the substrate. Mangrove organisms typically occur in saline conditions between that of brackish water and sea water. The sea water comprises about 35 gram per liter salt, i.e. an osmotic potential of -2.5 MPa. In some habitat types, such as salt flats, evaporation raises the prevailing salinity to twice that of the sea, where conditions become hypersaline. Mangrove forest plants are highly adapted to the adverse conditions of waterlogging and anoxic soil, salinity and high temperature. The two true mangrove plant species in Egypt, namely Avicennia marina and Rhizophora mucronata cope with this environment in different adaptive mechanisms. (a) Adaptation to waterlogging and anoxic soil. The roots of Avicennia marina are shallow and horizontal that radiate outwards. At intervals of some 15-30 cm vertical pneumatophores (respiratory roots) emerge up to 50 cm above the soil surface. A single tree of 2-3 m in height may have more than 10000 pneumatophores. The lenticels on the respiratory root surface allow gas exchange with the underground tissue. Roots tend to remain close to the soil surface and enter the seriously anoxic depths as little as possible. There are no deeply anchored taproots. Alternatively, the aerial roots of Rhizophora mucronata branch off (diverge) from the trunk as much as 2 m above the soil, elongate at up to 1cm per day, and penetrate the soil some distance away from the main stem. As much as 25% of the aboveground phytomass of the tree may consist of aerial roots.

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