Abstract:

Monthly investigations on fish assemblages were carried out in rocky reef habitat (RRH) in the Ma’an Archipelago using multi-mesh trammel nets in 2009, in order to find out the role of RRH in supporting local fish diversity. Fish taxonomic composition and ecological guild groups were used to examine species composition in detail. Indices such as Margalef’s species richness index, Whilm’s species diversity index, Pielou’s species evenness index as well as Pinkas’sIRI were used to analyze the status of fish diversity in RRH. A total of 87 fishes, belonging to 2 classes, 14 orders, 50 families and 73 genera, were collected. Fifty-one fishes from the family Perciformes (accounting 58.6% of the total species), 49 reef fishes (56.3% of the total species) and 7 stocked fishes (8% of the total species) were captured. Sixty-seven percent of total individuals were juveniles. There were 50 warm water fishes, 36 warm temperature fishes and 1 cold temperature fishes. Nineteen species lived on the reef surface, 46 lived in near-ground waters and 22 pelagic fishes frequently appeared in surface waters.Sebastiscus marmoratuswas the most dominant ground fish, Nibea albiflora was the most dominant species in near-ground waters and Thryssa kammalensis dominated the surface waters during summer and autumn. We considered 32 fishes to be local species, 55 were seasonal species and another 11 were casual species. Significant seasonal variation was detected; the lowest and highest diversity levels were found, respectively, in February and September. Our studies suggests that rocky reef habitat in Ma’an Archipelago was mostly used by reef fishes and warm water species. Juvenile fishes congregated in large numbers in these habitats during spring and summer. RRH also serves as habitat for fishes released from stock enhancement programs. We conclude that RRH are important coastal habitats because they offer feeding, spawning and nursing grounds for many fishes, especially juveniles of economically-important species. However, fish diversity has dropped in comparison to its original status in RRH habitats. We suggest that more attention should be paid to the management and conservation of rocky reef habitat.

Key words: rocky reef habitat, fish community, released species, ecological guilds, Ma’an Archipelago