Description of bivalve community structure in the Croatian part of the Adriatic Sea - hydraulic dredge survey

Hydraulic dredge surveys of bivalve communities in the Croatian part of the Adriatic Sea were conducted from the Island of Rab in the north to the river Neretva estuary in the south during 2007 and 2008. The main objective of the study was to describe distribution and community structure of bivalves on soft sediments along the eastern Adriatic, primarily focusing on commercially important species in five main bivalve harvesting areas. A total of 105 hydraulic dredge samples were collected at depths ranging from 1 to 11 m. Sampled bivalves were separated in the field and frozen for later laboratory analysis that included species identification, abundance and biomass determination. Live specimens of 54 bivalve taxa were collected during this study, while 87 taxa were represented by empty shells. Shells of the non-indigenous bivalve anadara demiri were recorded for the first time in the Croatian part of the Adriatic Sea. In terms of biomass and abundance the dominant species were acanthocardia tuberculata, Callista chione, Chamelea gallina, glycymeris bimaculata, g. glycymeris, g. violascens, laevicardium oblongum, Modiolus barbatus, Mytilus galloprovincialis, ostrea edulis and Venus verrucosa. Statistically significant differences were noted in bivalve communities in the five main sampling areas including the island of Rab, Pag bay, Kaštela bay, Cetina estuary and Neretva estuary.