"Relationship between the mysid Idiomysis tsurnamali and coelenterates such as the anemone Megalactis hemprichi and the jellyfish Cassiopea andromeda "

Info: a.gerlinde1@gmx.net

"Studies on the gobiid and shrimp mutualism in the Gulf of Aqaba"

Info: mariofreinschlag@gmx.at

Ecosystem services of coral reefs in the Gulf of Aqaba, Red Sea, Egypt:
does damage by divers modify their ecological or economic value and utilization?
Are there any other human or natural impacts?

Habitat Choice and Host Specialisation of the Coral-Dwelling Gobiid Genus Gobiodon in the Gulf of Aqaba (Northern Red Sea)

This study investigates the community structure of reef-building corals in terms of species composition, zonation, and diversity patterns. Furthermore the regional species pool is analysed in detail. The study site is a reef complex called The Islands, located in the Gulf of Aqaba. Three cross-sections are recorded, using a modification of photographed-quadrate-transect method as laid out by Laxton and Stablum (1974). Three different indices are calculated (Species Richness, Equitability, and Shannon-Wiener-Index of diversity) for estimating the diversity of different zones of the reef. The regional species pool is found to contain 204 species in 50 genera of scleractinian corals and 5 non-scleractinian species. Sheppard (1992) lists an indigenous group of seven corals with occurrence limited to the Gulf of Aqaba and its entrance. Four corals of this group are found to appear in The Islands. The highest number of species belongs to the family of Faviidae with 64 species, followed by the family of Acroporidae with 56 species, and the family of Poritidae with 25 species. Some of these species identified, had previously not been recorded as indigenous and are not listed in existing literature as abundant for the Read Sea. According to the total number of species identified in this study, the diversity in the Gulf of Aqaba is higher than assumed before. For diversity, total coverage of single species and relative coverage of species relative to each other was assessed and analysed. The indices calculated of the recorded data reflect a high diversity as well as a balanced abundance within the three reference sites. The zonation within The Islands is similar to the zonation of the Eilat reefs as described in Loya & Slobodkin (1971), while still maintaining certain peculiarities. Most importantly, Stylophora pistillata and Millepora dichotoma are neither dominating the reef flat nor the upper reef slope, respectively. The analysis results in the presentation of four coral communities within The Islands in this study. They contain elements of the principle coral communities of the Red Sea described by Sheppard (1988), but can not be attributed to a particular one. Dominant species found are: Acropora gemmifera and Acropora hyacinthus on the reef flat, Acropora muricata and Pocillopora verrucosa on the upper reef slope, and Acropora variolosa and Acropora valida on mid-lower reef slope. Furthermore, large areas are assembled and dominated by Porites nodifera. Surprisingly, Acropora gemmifera shows the highest coverage on the reef flat, since it is not mentioned in the findings of Sheppard (1992). Acropora muricata is known as a dominant species limited to shallow-water areas of the Gulf of Suez. This study reveals that it is a dominant shallow-water area species in the Gulf of Aqaba as well. So far, coral communities of mid-depths in the northern Red Sea were thought not to have dominant species. The reef slope of The Islands is characterized by a high diversity within stable coral communities, exemplified by the family of Faviidae. However, the coverage data collected for the single species Acropora variolosa shows a mean dominance of approximately 25 % on the mid-reef-slopes. Therefore, its dominance is doubtlessly shown to be considerably higher as the findings of Loya & Slobodkin (1971) previously suggested. Thus, Acropora variolosa has most likely been underestimated as a dominant species within the Gulf of Aqaba, a fact further supported by the Acropora variolosa – Acropora valida – Zoneof the Eilat reefs in which – as the name already suggests – Acropora variolosa is the dominant species.