Effect of Vibrio alginolyticus on larval survival of the blue mussel Mytilus galloprovincialis

The effect of increasing concentrations of Vibrio alginolyticus on survival of Mytilus galloprovincialis larvae was studied in a 48 h static bioassay in 11 glass bottles. Five bacterial densities were tested ranging from 10(2) to 10(6) bacteria ml(-1). Larval survival and normality (veliger larvae with the typical D-shape) were evaluated after 48 h. An inverse relationship between bacterial concentration and larval survival and normality was observed. In spite of high larval survival (79%) under conditions of high bacterial density (10(5) bacteria ml(-1)), the percent of normal larvae was 11 %. Besides an irregular shape, abnormal larvae also presented velum reduction. Results from this study suggest that concentrations of V alginolyticus lower than 10(3) bacteria ml(-1) should be maintained during M, galloprovincialis larval culture.