POPULATION PATTERNS, BIOLOGY AND ECOLOGY OF BIVALVES FROM LAGOONS AND ROCKY SHORES IN GHANA

Seasonal sampling of bivalves from three lagoons and two rocky shores adjacent to these lagoons were studied. Two types of lagoons are found in Ghana; “open” and “closed” lagoons. Data presented include; total wet body weight, shell size, lipid content, condition index (CI) and total dry body weight as well as the effect of season on these bivalves. Three bivalves sampled showed similar patterns of variation in condition index and lipid content in response to seasonal change. Food availability and rainfall seem to control the patterns observed. Among the three bivalves, oysters have the highest lipid content (81 mg/g dw) and cockles the least (48 mg/g dw). Oysters had the highest CI (147) and mussels the least (124). Dry season CI were higher than the wet season. There were significant differences in the CI on size classes (all p < 0.05). There was no relationship between CI and lipid content of the bivalves. Geographically, bivalves from Benya lagoon have more lipid than those from Ningo and Sakumo lagoons. Seasonal differences at the stations might have been a reflection of the stage of gonad maturation or reproductive cycle.