Abstract
In August 1975 a stratified random sampling programme at 46 stations was performed. The highest number of species, 21, was found in shallow water (5–19 m), whereas the highest biomass, 132.04g/m2, was found between 20 and 29 m depth. Diastylis rathkei (Crustacea; Cumacea) and Macoma balthica (Mollusca; Bivalvia) showed the widest distribution and were found at 37 and 36 stations respectively. Community analyses were made by both qualitative and quantitative methods, which yielded six and seven associations respectively. The species found could be divided in three groups with different depth distribution correlated with hydrological discontinuities. The high degree of persistence in community structure is discussed.