Spatial variation of molluscan fauna associated with Cystoseira assemblages from a semi-enclosed gulf in the Aegean Sea

Abstract The spatial dynamics of the molluscan fauna associated with Cystoseira spp. assemblages of the upper sublittoral were analyzed, in a semi-enclosed gulf in the Aegean Sea, in April 2009. The faunal samples were collected by SCUBA diving from 4 locations along the coastline, 2 on each opposing side of the Pagasitikos gulf. A total of 1363 individuals belonging to 41 species were identified, with the gastropods being the dominant group. The most abundant and frequent species were Bittium reticulatum , Bittium latreillii and Alvania aspera . All feeding guilds were represented, with the most dominant being micrograzers followed by filter feeders. Molluscan community structure displayed significant spatial variation in terms of diversity and abundance. The hydrodynamic regime of the area seems to be a decisive factor that affects both the algal biomass and the molluscan abundance and distribution.