Hyperbenthic community structure over oligotrophic continental shelves and upper slopes: Crete (South Aegean Sea, NE Mediterranean)

The community structure of hyperbenthos on continental shelves and upper slopes of oligotrophic areas have been little studied. The present study, located in the eastern Mediterranean (Heraklion Bay, Crete) gives the first description of this using samples collected at depths ranging between 50 and 300 m in two seasonal occasions (March and September 2001) using a modified hyperbenthic sledge (0.5 mm mesh size) specifically designed to resuspend the sediment surface and to sample simultaneously the hyperbenthic macrofauna. The analysis revealed 96 different taxa (Peracarida and Decapoda) with densities ranging from 198 to 2618 ind 100 m−2 and indicated the presence of a clear zonation of the hyperbenthic communities along a depth gradient as well as different diel and seasonal adaptations to the prevailing environmental conditions of the community structure. Artificial resuspension of the sediment surface revealed that the highest proportion of the hyperbenthic macrofauna collected in this oligotrophic environment (74–100 %) was found to reside at the sediment–water interface (0–0.05 m). This demersal behaviour seems to be a response to high light levels close to the seabed and availability of food sources associated with the sediment surface.