Preliminary Investigations of the Benthic Ecosystem from the Aegean shelf (Eastern Mediterranean) <B>Preliminary Investigations of the Benthic Ecosystem from the Aegean shelf (Eastern Mediterranean)</B><P> Anastasius Eleftheriou and Chris J. Smith</B><I><P> Institute of Marine Biology of Crete, P.O. Box 2214, 710 03 Iraklion, Crete, Greece</I><B><P> Abstract</B><I></I><P> A preliminary shelf investigation of the Southern Aegean Sea was undertaken in September 1988 during which four stations at 70m, 100m and 160m were sampled. Ten replicate grab samples (0.1 m(2)) were taken for macrofaunal analysis (sieved through 500 Ìm mesh) and one additional grab sample for physico-chemical measurements, which gave the following results. I.) Sedimentary organic carbon decreased with depth and median grain size from 5.26 mgg(-1) to 3.94 mgg(-1). Chlorophyll <I>a</I> also generally decreased with depth but there was a peak at 100m of 1.45Ìgg(-1). ATP had variable measurements with depth with values around 200-400ngg(-1).II). A total of 379 macrofaunal species comprising 11 548 individuals was identified, with polychaetes the dominant group representing 58% of the species and 66% of the abundance. Average species number and abundance both showed significant decline with depth. Diversity and eveness were both high, although the size of the macrofauna was in general rather small. III). Ten dominant species had variable distributions with depth. The polychaetes <I>Thryx heterochaeta</I>, <I>Magelona minuta</I>, <I>Euclymene palemitana</I> and the sipunculids <I>Onchnesoma steenstrupi</I> and Sippunculid Sp. X all decreased in abundance with depth. The polychaetes <I>Rhodine</I> <I>loveni</I> and <I>Sarsonuphis fragosa</I> increased in abundance with depth. The polychaetes <I>Tharyx marioni</I> and <I>Tauberia gracilic</I> and the bivalve mollusc <I>Axinulus croulinensis</I> had highest abundances at intermediate depth. IV). Polychaete feeding guilds were investigated. Surface deposit feeders were dominant at all stations (50-70%). Both surface deposit feeders, notably tentaculate polychaetes decreased with depth. Omnivore/ scavengers and polychaetes possessing soft probosci showed an increase with depth. V.). From the data presented, depth seemed to be the principal factor in regulating the macrofaunal community. However, many physico-chemical environmental factors are linked with depth as well as to the distance from the shore and the proximity of terrestrial inputs. Thus, it was concluded that the general theory of food limitation controlling macrofaunal community structure was particularly valid for the Southern Aegean shelf.<P> Symposium Mediterranean Seas 2000. Ed. by N. Della Croce. ISAM. Santa Marherita Ligure pp. 105-120.<P>