Fish Fauna Diversity in Relation to Habitat Structure at an Isolated Fringing Reef at Masbat Bay, Dahab, South Sinai, Egypt -Bachelor Thesis- Katharina Fietz

Abstract

Diversity of a fish assemblage was determined and compared to substrate structure, to the amount of coral damage, as well as to defined environmental variables on an isolated fringing reef off the coast of Egypt. A total of 95 different species belonging to 35 families were counted in the reef adjacent to the tourist resort town Dahab. Labridae and Pomacentridae dominated fish assemblages in terms of species diversity while Pomacentridae were most abundant with 1262 counted individuals out of a total of 4165.

Abiotic cover was the most frequented in substrate analysis followed by life coral cover and algae cover. The reef divided into three main zones: the coral area in the centre showed highest live coral cover dominated by Acropora spp. and highest fish abundance. The area closest to shore showed high algae cover and high abiotic cover and was dominated by Porites, while a high abiotic cover and low coral cover defined the outer edge of the reef area. Variation in total number of fishes between transects, variation in reef fish diversity, as well as distribution of the most abundant fish species and significant changes of abiotic cover between transects further clarified this differentiation of the reef.

Multivariate analyses showed that substrate structure influenced fish assemblages strongest of all investigated environmental variables. Water depth, distance from shore, and distance from the beginning of the reef also revealed a good correlation to fish assemblages. Analysis of coral damage correlation to fishes suggested little influence of damaged coral colonies on variation in fish assemblages. Results of coral damage data analyses, however, can only limitedly be interpreted due to a lack of relative amounts of damage in the reef. Diurnal changes in fish assemblage composition were not detected.

Cryptobenthic Fish of the El Quadim Bay, El Quseir, Egypt

-Bachelor Thesis- Andreas Scharl

Abstract

This study establishes a preliminary species list of cryptobenthic fishes: Apogonidae (four species), Blennidae (eight species), Gobiidae (thirteen species) and a Plesiopidae, on Egypt's mainland Red Sea coast. Different methods of capturing and/or identifying these fishes are evaluated, among them interference visual census and anaesthetisation by clove oil as well as fish traps and a ground-net filled with coral rubble. Clove oil proved to be most effective and a valuable tool when studying small and cryptic fishes. Additionally the habitat preferences of the studied species have been listed revealing hard substrates such as coral rubble, rock and live corals to be of greater importance to cryptobenthic fish than sandy bottoms. A certain bias towards species living on the reef flat has to be acknowledged as it was easy to catch fish hiding in pools and channels at low tide and the time dedicated to capturing fish during research dives was limited.