Shore fish community structure off the Jordanian Red Sea coast was determined on fringing coral reefs and in a seagrass-dominated bay at 6 m and 12 m depths. A total of 198 fish species belonging to 121 genera and 43 families was recorded. Labridae and Pomacentridae dominated the ichthyofauna in terms of species richness and Pomacentridae were most abundant. Neither diversity nor species richness was correlated to depth. The abundance of fishes was higher at the deep reef slope, due to schooling planktivorous fishes. At 12 m depth abundance of fishes at the seagrass-dominated site was higher than on the coral reefs. Multivariate analysis demonstrated a strong influence on the fish assemblages by depth and benthic habitat. Fish species richness was positively correlated with hard substrate cover and habitat diversity. Abundance of corallivores was positively linked with live hard coral cover. The assemblages of fishes were different on the shallow reef slope, deep reef slope and seagrass meadows. An analysis of the fish fauna showed that the Gulf of Aqaba harbours a higher species richness than previously reported. The comparison with fish communities on other reefs around the Arabian Peninsula and Indian Ocean supported the recognition of an Arabian subprovince within the Indian Ocean. The affinity of the Arabian Gulf ichthyofauna to the Red Sea is not clear.

This study investigates the molecular phylogeny of seven lionfishes of the genera Dendrochirus and Pterois. MP, ML, and NJ phylogenetic analysis based on 964 bp of partial mitochondrial DNA sequences (cytochrome b and 16S rDNA) revealed two main clades: (1) "Pterois" clade (Pterois miles and Pterois volitans), and (2) "Pteropterus-Dendrochirus" clade (remainder of the sampled species). The position of Dendrochirus brachypterus either basal to the main clades or in the "Pteropterus-Dendrochirus" clade cannot be resolved. However, the molecular phylogeny did not support the current separation of the genera Pterois and Dendrochirus. The siblings P. miles and P. volitans are clearly separated and our results support the proposed allopatric or parapatric distribution in the Indian and Pacific Ocean. However, the present analysis cannot reveal if P. miles and P. volitans are separate species or two populations of a single species, because the observed separation in different clades can be either explained by speciation or lineage sorting. Molecular clock estimates for the siblings P. miles and P. volitans suggest a divergence time of 2.4-8.3 mya, which coincide with geological events that created vicariance between populations of the Indian and Pacific Ocean.

Competition drives habitat segregation between adults and juveniles in many types of organisms, but little is known about this process in anemonefish that compete for host sea anemones which differ in habitat quality. We performed field and laboratory experiments to determine causes of habitat segregation in 2-band anemonefish Amphi prion bicinc tus on coral reefs in the northern Red Sea, where juvenile fish mainly occupy leathery sea ane mones Heteractis crispa, and breeding adults almost exclusively inhabit bulb-tentacle sea anemones Entac maea quadricolor. E. quadricolor were usually larger than H. crispa, and expanded more in response to fish presence. Adult fish visually concealed a larger proportion of their body surface area among the relatively thick tentacles of E. quadricolor than among the thinner tentacles of H. crispa, while juveniles were concealed equally well in both hosts. During field experiments, vacated E. quadricolor were colonized rapidly by fish, whereas H. crispa were not. In laboratory choice experiments, fish at all post-settlement life stages preferred E. quadricolor, and large individuals monopolized this host and relegated subordinates to H. crispa. We conclude that competitive exclusion drives habitat segregation among life stages of this anemonefish and that host anemone traits underlie this process. The non-preferred host H. crispa may func tion as a refuge for juvenile fish while they wait for space to become available in the preferred host E. quadricolor, where they are able to attain sexual maturity. The tentacles of the sea anemone Entacmaea quadricolor offer optimal cover for anemonefish Amphiprion bicinctus.

The semi-enclosed Gulf of Aqaba is under high pressure by urban and industrial pollution, shipping and port activities as well as tourism. Off the Jordanian Red Sea coast, the trophic community structure of shore fishes was determined on coral reefs in front of an industrial area (disturbed), in a marine reserve and site without industry or port activities (undisturbed), as well as in a seagrass-dominated bay. Planktivores were the most abundant feeding guild on coral reefs as well as in the seagrass-dominated bay. The relative abundance of feeding guilds other than planktivores seems to be strongly influenced by the benthic habitat. Multivariate analysis clearly separated disturbed from undisturbed sites, whereas univariate measures, such as species richness, diversity and evenness did not reveal any negative impact of disturbance. The disturbance of the coral reefs led to changes in the fish community through the reduction of total fish abundance by 50%, increased total abundance of herbivorous and detritivorous fishes, decreased total abundance of invertebrate-and fish-feeders, and increased relative abundance of planktivorous fishes.

The Jordanian coast of the Gulf of Aqaba was intensively surveyed during the year 2004 to assess the health of the coral reefs in Jordan. Permanent line transects were laid on the reef flat, at depths of 8 m and 15 m at eight sites, and selected benthos components were studied. It was found that the distribution of hard corals increases gradually from north to south and that the 15 m deep transects had the highest coverage of hard corals. On the other hand, soft corals showed the highest coverage at sites where industrial activities are taking place. Coral death was low along the Jordanian coast and is comparable to surveys made in previous years, though protection measures are needed at the sites where industrial and recreational activities are focused. The hotels area, the phosphate loading berth and the Tala Bay sites had more than 40% seagrass coverage and were classified as seagrass habitats. Giant clams were hardly found on Jordan's reefs and it is suggested that they should be considered as endangered species. It is concluded that the coral reefs in Jordan are in good condition, although pressure resulting from the rapid development of the tourism, industry and construction sectors along the coast is expected to increase and to represent the major threat to this ecosystem in the future. Continuous monitoring is therefore suggested.Kurzfassung. Um den Zustand der Korallenriffe entlang der jordanischen Rotmeerküste zu untersuchen, wurde 2004 eine intensive Felderhebung durchgeführt. Permanente Transekte, an denen ausgewählte Benthosgemeinschaften studiert wurden, wurden an 8 Stellen an der Riffplattform und in 8 bzw. 15 m Tiefe gelegt. Es zeigt sich, dass die Steinkorallen von Norden nach Süden allmählich zunehmen, und dass im 15 m-Tiefenbereich die höchste Dichte von Steinkorallen zu finden ist. Andererseits zeigen Weichkorallen an Orten mit industriellen Aktivitäten ihre höchste Dichte. Korallensterben wurde an der jordanischen Küste im Vergleich zu früheren Jahren nur selten festgestellt, obwohl in Gebieten mit industriellen und touristischen Aktivitäten Schutzmaß-nahmen empfohlen werden. Im Hotelgebiet, der Phosphatverladestation und in der Bucht von Tala waren die Sammelstellen zu mehr als 40% von Seegras bedeckt und wurden daher als SeegrasHabitate klassifiziert. Große Muscheln werden zwischen den Korallen nur ausnahmsweise gefunden und werden als bedroht eingeschätzt. Aus den Ergebnissen wird geschlossen, dass sich die jordanischen Korallenriffe in gutem Zustand befinden, obwohl die rasche Entwicklung des Tourismus und der Industrie sowie diverse bauliche Maßnahmen Gefahren für das Korallenökosystem darstellen, die auch in Zukunft weiter zunehmen werden. Es wird daher ein kontinuierliches Monitoring vorgeschlagen.