Concentrations of seven heavy metals (Cu, Zn, Pb, Cd, Ni, Co and Fe) were measured in the seawater, sediments, common scleractinian reef-building corals and soft corals (Octocorallia : Alcyonacea) at seven reef sites in the Northern Red Sea: I (Hurghada), II (Ras Za'farana), III (El-Ain Al-Sukhna), IV (El-Tur), V (Sha'b Rashdan), VI (Sharm El-Sheikh) and VII (Dahab). Levels of heavy metals were considerably elevated in seawater, sediments and corals collected from reef sites exposed to increased environmental contamination, as a result of diversiWed natural and anthropogenic inputs. Soft corals of genera Lithophyton, Sarcophyton and Sinularia showed higher concentrations of Zn, Pb, Cd and Ni than hard coral genera Acropora and Stylophora. Soft coral Sarcophyton trocheliophorum collected from El Ain Al-Suhkna (Gulf of Suez) had greater concentration of Cu, followed by hard corals Acropora pharaonis and Acropora hemprichi. The elevated levels of Zn, Cd and Ni were reported in the dry tissue of soft coral Sinularia spp. On the other hand, the soft coral Lithophyton arboreum displayed the highest concentration of Pb at Sha'b Rashdan (Gulf of Suez) and elevated concentration of Zn at Sharm El-Sheikh. Sediments showed signiWcantly higher concentration of Fe than corals. The higher levels of Fe in hard corals than soft corals reXected the incorporation of Fe into the aragonite and the chelation with the organic matrix of the skeleton. The greater abundance of soft corals in metal-contaminated reef sites and the elevated levels of metals in their tissue suggesting that the soft corals could develop a tolerance mechanism to relatively high concentrations of metals. Although the eVects of heavy metals on reef corals were not isolated from the possible eVects of other stresses, the percentage cover of dead corals were signiWcantly higher as the concentrations of heavy metals increased.

Chemical investigation of an ethyl acetate soluble fraction of Sinularia polydactyla (Ehrenberg) led to the isolation of three known terpenoides, two of them sterols, 24-methylcholestane-3β,5α,6β,25-tetrol 25-monoacetate (1), 24-methylcholestane-5-en-3β,25-diol (2), in addition to a cembranoid diterpene, durumolide C (3), for the first time. The cytotoxicity and antimicrobial activities of the ethyl acetate extract and the isolated compounds 1-3 were evaluated in vitro. Durumolide C (3) showed selective cytotoxicity against HepG2 (IC50 1.0 μg/mL), whereas 24-methylcholestane-3β,5α,6β,25-tetrol 25-monoacetate (1) showed IC50 of 6.1 and 8.2 μg/mL against Hep2 and HCT human cancer cell lines, respectively.

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F ifteen water quality parameters and nine coral community variables were assessed in eight reef sites along the Red Sea coast of Egypt. Coral reef environments are suffering of stress from increased anthropogenic activities, particularly in the vicinity of heavily populated and touristic areas such as Hurghada, Ain Al-Sukhna and Sharm El-Sheikh. Increased terrestrial runoff of sediments, nutrients, organic matter and other pollutants are the main causes of water quality deterioration in the investigated reef sites. The results showed that bioerosion of corals by sea urchins, and enhanced abundance of macroalgae and consequent competitive overgrowth of corals were the major reasons of coral damage observed in the area of study. Population density of sea urchins exhibited significant and positive correlations with the majority of eutrophication parameters. Salinity was significantly and negatively correlated with live hard coral cover. Exceeding levels of DIN and TSM above the threshold concentrations for eutrophication were reported to be indirectly and adversely affecting coral reefs through stimulating the growth of macroalgae, enhancing sea urchin density and reducing water transparency. The results support the predictions of bottom-up hypothesis that confirm the critical role of eutrophication in structure of coral reef community.

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Herbivorous reef fishes are critically important for maintaining the health and resilience of coral reefs. In the Egyptian Gulf of Aqaba (GoA), many of these herbivores are important fishery targets and little is known about their population size structure and biomass patterns. Here, we conduct a large-scale (~250 km of coastline) assessment of the status of herbivorous fish populations along a fishing pressure gradient at 30 sites and eight regions in the GoA. These regions are subjected to three levels of fishing and protection, ranging from almost no fishing (No take, NT), and moderately fished (via Gear restriction, GR) to heavily fished (Open access, OA). We found that the NT fishery reserve was the most effective to maintain herbivorous fish size, biomass, and richness across all functional groups, though numerical density was not. Total herbivore biomass was 4.3 and 2.8 times higher on NT reefs and GR reefs, respectively than on OA reefs. Among GoA regions, only Ras Mohammed and Sharm El-Sheikh (unfished), and Nabq (fished) met the global mean herbivore biomass target of ~30 kg/500 m2. Our work also highlights three important results regarding the impacts of fishing and fisheries management on herbivorous fish populations: (i) size structure was heavily skewed toward smaller individuals, with fishes less than (20 cm) accounting for 81.1% of the population in heavily fished OA reefs vs. 52.8% at unfished NT reefs, (ii) biomass of larger herbivore individuals (>35 cm) accounting for less than 1% of the total biomass in OA reefs vs. 37% at NT reefs, and (iii) large-bodied target species, Cetoscarus bicolor, Naso unicorn, and Kyphosus spp., accounting for 15.9% of the total biomass at NT reefs on average, while they were virtually absent from OA reefs. Collectively, these findings suggest that many principal fisheries species in the central northern regions of the GoA have been overexploited, which in turn can lead to reef degradation. Therefore, there is an urgent need to develop a participatory management approach and enforce restrictions on destructive fishing gear in order to promote recovery of herbivore biomass.

This study is trying to assess the types and frequencies of occurrence of coral diseases. Are these diseases due to the impacts of global warming or tourism on coral reefs along the Red Sea coast off Hurghada? Results indicated that there is a high disease prevalence (46 %) with the presence of four coral diseases/ syndromes; White Syndrome (21.6%), Bleaching (16.2 %), Black Band Disease (8.2%) and overgrowth of sponge were near the sampling transects. Data of the Coral Reef Watch about the Sea Surface Temperature (SST) anomaly produced by National Oceanographic and Atmospheric Administration (NOAA) indicated that there was 1°C increase in SST in 2009 and 1.5°C increase in 2010 in the northern Red Sea region. The increased prevalence of coral diseases in the Red Sea coast off Hurghada might be attributed to sea surface temperature (SST) anomaly due to global warming. It might be also due to activities associated with tourism such as exaggerated coastal development through construction of hotels and increased sewage run off and unregulated recreational activities such as SCUBA diving, snorkeling, and reef walking. Coral reefs must be considered and incorporated into management plans. To conserve these valuable marine resources, we have to adopt the sustainability concept of ecotourism instead of mass and random tourism activities.Hany, A. Abd-elsalam et al. 34 cause significant changes in community structure, species diversity and reefassociated organisms (Beeden et al., 2008).Although coral disease is emerging as a serious cause of coral reef deterioration in many reefs around the world, at present very little is known about the ecology or pathology of coral diseases in Red Sea reefs, in general (Antonius and Riegl, 1997).Increases in temperatures around the globe and changes in weather patterns, particularly El Niño Southern Oscillations, are dramatically influencing the health and composition of coral reefs through outbreaks of significant bleaching events. In 1998, the most widespread bleaching event on record swept across the globe, and destroyed 16% of the world"s coral reefs (Mydlarz et al., 2010).