Deep-sea meiofaunal community structure in the Eastern Mediterranean: are trenches benthic hotspots?

The abundance and community structure of metazoan meiofauna were investigated in deep-sea sediments of the eastern Mediterranean basin, along a transect from the Gulf of Taranto (Italy) to the coast of Egypt and Israel. Total meiofaunal abundance ranged from 4 to 435 ind./10 cm2. Lowest values were found at the deep offshore areas (4–40 ind./10 cm2), whereas highest values were found near the Israeli coast and over the shallow continental shelf off the Nile delta (435 and 304 ind./10 cm2, respectively). Surprisingly high values were found in the Hellenic and Pliny Trenches, where total meiofaunal abundance ranged from 45 to 156 ind./10 cm2. At all stations, nematodes dominated the samples (range 41–84%), followed by harpacticoid copepods and polychaetes. The only exception was the Pliny Trench station, where harpacticoid copepods dominated the samples (78%). Meiofauna abundance and community composition changed with water depth and distance from coast, and were influenced by food availability (sedimentary chlorophyll pigment concentrations and organic carbon).