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Distribution, coverage and the species composition for seagrasses along 89 km of the shoreline of Wadi El Gemal National Park (WGNP) in the southern of Egyptian Red Sea coast. 26 meadows of seagrass were marked, mapped and seagrass diversity and abundance were investigated. Eleven species of seagrasses were recorded; four species were new records to the whole Red Sea, the Egyptian waters of the Red Sea and WGNP. Halodule pinifolia (Miki) den Hartog is newly recorded to the whole Red Sea, while Enhalus acoroides (L.f.) Royle, represents a new record to the Egyptian waters of the Red Sea. Halophila decipiens Ostenfeld and Cymodocea serrulata (R.Brown) Ascherson were recorded for the first time in the area of WGNP. The total area of meadows estimated 1783.08 ha with range 498.2 ha to 0.024 ha. The seagrass coverage ranged between (82.5% ±8.7) and (17.5% ±8) in different sites. However, the higher overall mean coverage was recorded at sheltered sites than exposed sites. H. stipulacea was the most dominant species. The total coverage of seagrass found to be higher at shallower and deeper waters, rather than the middle depths of 5-20m. The highest richness value was 1.001 in front of Wadi El Gemal catchment basin, while the depth 0-5m (1.495) had the highest richness and evenness. Introduction Seagrasses are defined as marine flowering plants (angiosperms). As such, they live and complete their whole life cycle submerged in seawater (including underwater flowering, pollination, distribution of seeds and germination into new plants). Seagrasses grow in a wide range of habitats ranging from the intertidal to depths of over 70 m (Jones et al., 1987; Long et al., 1996). The Red Sea harbors 11 seagrass species, all of tropical origin, which penetrated through its relatively narrow mouth at Bab al Mandab. (den Hartog, 1970; Aleem, 1979; Jacobs and Dicks, 1985). Only a single plant of Halophila decipiens has hitherto been reported from the Red Sea, grabbed from 30 m (Jacobs and Dicks, 1985). Enhalus acoroides seems not to reach much beyond the Tropic of Cancer, whereas the other ten species continue to the northwestern part of the Red Sea proper, but only seven (the above listed species excluding Enhalus acoroides, Cymodocea serrulata, Halophila ovata and Halophila decipiens) penetrate into most of the Gulf of Aqaba and only five (Halodule uninervis, Halophila stipulacea, Halophila ovalis, Halophila decipiens and Thalassodendron ciliatum) into much of the Gulf of Suez. Wadi El Gemal National Park (WGNP) encompasses a great diversity of habitats in a uniquely compact setting, representing a complete terrestrial/marine ecosystem characteristic of the Red Sea coast. The region is of phenomenal natural beauty and outstanding biological diversity. The current study was aimed to investigate different ecological aspects of the seagrass communities. The scope items were: Surveying the marine area of Wadi El Gemal National Park (WGNP) by Demarking and mapping the main meadows in the study area and estimated the areas of seagrass meadow; Study the spatial variations in abundance and diversity of seagrasses with different depths. Methods Wadi El Gemal National Park (24° 45' N, 35° 3' E), is located about 35 km south of Marsa Alam City. 26 sites were selected to represent different conditions, i.e lagoon and sharms, inshore and offshore, and shallow and deep waters (> 20m) (Fig. 1). The methods used to map the distribution of seagrass meadows varied according to the marine zone, water depth and water clarity. At the intertidal zone, demarcation of meadows was conducted at low tide when the seagrass meadow was exposed and its boundaries were cleared. This was carried out by walking around the outer boundaries of each meadow with (GPS, GARMIN etrix Vistae). Regarding the shallow subtidal zone (<10m depth), the method used to map and demarks seagrass meadows were based on depth and water clarity as follow: In areas of high clarity, the boundaries of meadows mapped from a boat driven slowly (1-2 knots) around the perimeter of each meadow with single fixed position and recorded every 4 seconds (GPS set to “Track”). A snorkeling used to assist in identification of the presence of continuous or sparse meadows and the determination of deep edge meadows. In the case of the deep water (>10m depth), the seagrass meadows were mapped, using a grid pattern or a combination of transects and spots, much in the same manner as when mapping shallow subtidal meadows, but completely based on SCUBA diving. Seagrass meadows were mapped using the GIS capabilities and application (ArcMap vers. 9.1). At each meadow, the shore profile and seagrass distribution were plotted. To estimate the diversity and abundance of seagrasses, 26 transects ranges between 25m to 250m length each perpendicular to the shore. In each transect seagrass diversity and abundance was estimated. Four quadrates of 1m x 1m (1m2) each were laid randomly per transect. Identification of seagrass species was based on: Phillips and Menez, (1988), Kuo and Den Hartog (2001) and Waycott et al. (2004). Additional advice on the taxonomic status of the genus Halodule in the Indian Ocean was provided by Pro. F. T. Short (founder of SeagrassNet organization) Results Eleven species of seagrasses were recorded from the area of WGNP: namely Halophila stipulacea (Forsskal) Ascherson , Halophila ovalis (R.Brown) Hooker f., Halophila decipiens Ostenfeld, Thalassia hemprichii (Ehrenberg) Ascherson, Enhalus acoroides (L.f.) Royle, Halodule uninervis (Forsskal)

Distribution, Abundance and Species Composition of Seagrasses in Wadi El Gemal National Park, Red Sea, Egypt