REGIONAL MARINE BIOLOGY
Sedimentary slopes
The majority of the seabed consists of gently sloping silty clay sediments, that appear to be quite bare and barren with little sign of life – desert-like. However the sediment is visibly inhabited and this is evidenced by bioturbation features on the surface, either through small feeding pits, shallow bulldozed feeding and moving trails and also burrows. These were mostly highlighted by exposed lighter brown/grey sediments under slightly darker grainier surface sediment. Burrow systems were characterized by collections of small vertical surface openings, probably made by burrowing crustacean shrimps. Visible invertebrate fauna on the sediment surface included the sea-pen Funiculina quadrangularis, the starfish Brisingia coronata, the thick armed sea urchin Cidaris cidaris and dead tests (shells) from the burrowing urchin Spatangus purpurea. A small number of fish were found on the sediment surface including the rat-tail Nezumia sclerorhynchus, Chlorophthalmus agassizii, and the lizardfish Synodus spp.
Parallel marks seen on the side scan sonar records across part of the survey area indicated the presence of trawling in the recent past. This activity would have been targeted at the deep red shrimp Aristeomorpha foliacea and Aristeus antennatus and is most certainly from visiting Italian fishing vessels working outside the Greek 6 mile national limit.
Hard Bottom Outcrops and Crusts
In comparison to the sedimentary system small outcrops and crusts seemed to form oases-like micro-environments in this desert. These hard objects, from centimeters to metres in extent, had both associated mobile fauna and encrusting fauna. The associated mobile fauna included very high numbers and biomass of the shrimp Plesionika spp. sometimes blanketing the hard substrate and the sediment in close vicinity. Fish included large groupers, solitary or in pairs. On a few occasions, a conger eel and some smaller unidentified fish inhabited larger outcrops. One outcrop was home to an octopus. The encrusting fauna included most importantly corals: a short thick low branching coral with a few large polyps, possibly the cold water coral Madrepora oculata (provisional identification, which if confirmed could be the most southerly and easterly recorded occurrence of this species). More rarely whip corals and fan-like gorgonian corals were observed. The Madrepora colonies had few live heads, but small rubble piles of old coral colonies grouped in close vicinity. The hard substrate was also colonized by some white anemones and encrusting coralline tubiculous polychaete worms.
Dr. Chris Smith, Marine Biologist, Institute of Marine BIological Resources, HCMR
