GENETIC ASPECTS OF LARVAL GROWTH UNDER REDUCED SALINITY INMYTILUS EDULIS

Abstract

Adult mussels (M. edulis) were collected from a Nova Scotia (Canada) bay which experiences a seasonal fluctuation in salinity between 18 and 30%. Larvae derived from the spawned adults were used in a number of experiments to partition observed variation in growth into genetic, environmental and interactive components. Thirty-six families, produced from a factorial mating of 6 males and 6 females, were raised at 2 salinities (30 and 12%). Measuring larval length 16 days after fertilization showed that males, females, salinities and all interactions from the 3-way analysis of variance had a significant effect on larval growth. A similar experiment involving 8 families derived from single pair crosses also gave significant interaction between families and salinities. There was no average effect of salinity between 18 and 30% but salinities below 18% significantly decreased growth. These results are interpreted with reference to the salinity variation experienced by the natural population. Such breeding studies are beginning to be used as a means of understanding the genetic and environmental variations observed in a number of marine organisms.