Comparative biometry of Eunicella singularis (Gorgonian) sclerites at East Mediterranean Sea (North Aegean Sea, Greece)

Abstract

The two forms of Eunicella singularis sclerites, spindles and clubs, were examined in two sites in East Mediterranean Sea, Greece. The comparison of the sclerites size was based on the hydrodynamic proWle of the sites (the site of Arethoussa was exposed and the Phidonissi site was sheltered), on the sites bathymetry (AR 5–8 m, AR 9–13 m, PH 5–10 m, PH 11–13 m) and on the position occupied by the sclerites on the gorgonian colonies (top, middle and base). With the usage of image system analysis the following microfeatures were measured or calculated: projection, length, width, elongation factor, compactness factor, length £ width and length/ width. The present study conWrms the hypothesis that spindles are involved in the recovering of the gorgonian colonies and clubs contribute to the Xexion capacity of the colonies. The spindles of the shallow E. singularis colonies (AR 5–8 m) were signiWcantly bigger (length, width) compared with the others, in order to assure the best recovery of the colonies after their Xexion, induced by higher water current velocity in shallow water. The clubs occupy the intern part of the mesoglea and their size (length, width) increased in colonies from the shallow exposed site in order to facilitate the gorgonian Xexion. The present study demonstrates the gorgonian adaptation (in a microscopic scale) to the environmental pressure of hydrodynamic conditions.