Depth-related gradient of soft-bottom crustacean distribution along the Cilician shelf


Abstract: Distribution of crustaceans in 3 transects (including depths of 10, 25, 50, 75, 100, and 200 m) of oligotrophic soft bottoms of the Levantine Sea shelf located near Kumkuyu, Limonlu, and Erdemli was studied in 2000 to show its association with depth-dependent environmental parameters in representative months of each season (winter, spring, summer, and autumn). A total of 90 crustacean species was found; species richness was highest in winter and autumn and between 50 and 100 m in depth. There was a peak value in abundances in the warm season and at a depth interval of 10 to 50 m, whereas highest values of biomass were recorded in May and August and at a depth of 25 m. A seasonal variation at depths shallower than 75 m was observed for evenness values, which were more stable in deeper waters in all seasons. Two main crustacean assemblages were determined, the first corresponding to shallow bottoms (10, 25-100 m) and the other to deeper bottoms (150-200 m). Besides the grain size and total organic carbon content of the sediment, depth is the most important factor in determining the crustacean assemblage. Hydrographic characteristics of the water column made up 2 seasonal crustacean assemblages: the first in February and May, and the other in August and November. Therefore, all factors governing the crustacean distribution were found to be related to the bottom depth.

Keywords: Zoobenthos, crustaceans, distribution, eastern Mediterranean shelf

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