Genetic Aspects of Larval Growth Under Reduced Salinity Inmytilus Edulis

Adult specimens of Mytilus edulis in spawning condition were collected from a shallow, enclosed bay which was known to experience fluctuations in salinity. Growth of the resulting larvae was measured under different salinity conditions in the laboratory. 2. There was no significant difference in mean length between larvae raised at 30‰ and those raised at 18‰ after 18 days of growth. Salinities below this significantly decreased growth. 3. Families of larvae of known parentage were raised at different salinities. 4. The genetic analysis indicated substantial genetic variation in larval length measured 16 days after fertilization, as well as significant genetic interaction with salinity. 5. This is interpreted as the presence of genes influencing larval growth which depend on salinity for their expression and may be related to the past selective influence of a fluctuating environment. 6. These quantitative genetic techniques provide a useful approach to studying genetic variation in marine organisms and its interaction with the environment.