Distribution and abundance of the sand star Astropecten irregularis (Pennant, 1777) (Echinodermata, Asteroidea) on the continental shelf in the northern and middle Adriatic Sea

Abstract

            The sand star Astropecten irregularis (Pennant, 1777) is a very common species in the Adriatic Sea. This study establishes the distribution, biomass and abundance of that species on the continental shelf of the open waters in the northern and middle Adriatic Sea based on experimental sampling by bottom trawl during 11 cruises of the “Pipeta” Expedition (1985-1994). Five hundred and eighteen bottom trawl hauls were performed at 56 predetermined permanent stations along ten transects, over different sediment types at depths of 10 to 430 m. Astropecten irregularis was recorded in 82.2% of the hauls, with the highest biomass and abundance indices at depths from 10 to 50 m. The deepest record was in a haul from 313.5 to 412.5 m depth. Even though it was recorded all over the investigated area, it was most abundant in some areas of the northernmost part of the Adriatic, and very abundant in the areas along the western coast. The highest average biomass and abundance indices were recorded on sand-silt-clay sediment, on silty sand and sandy silt and on the clayey silt and silty clay.