Effect of sandy and muddy substrates on the growth and survival of the freshwater clam Galatea paradoxa (Born 1778)

This study was conducted to determine the effect of a sandy and muddy substrate on the growth and survival of three size-classes of Galatea paradoxa (Born 1778). The experiment was conducted over a 6-month period in a 1000 m² pond at the research farm of the Faculty of Renewable Natural Resources. Three size classes (shell length) of G. paradoxa categorized as small (20-30 mm), medium (31-40 mm) and large (>40 mm) were used to ascertain the effect of a sandy and muddy substrate on growth performance. Growth in general was very slow, between 1.4 and 2.4 mm over the 6-month experimental period. The lengths measured at the end of the experiment were also significantly different. However, the mean length gained and the specific growth rate for the three size classes in the two substrates (sandy and muddy) were not significantly different (P>0.05). The results of this study indicate that the pond environment is not suitable for the culture G. paradoxa as the species is adapted to life in a river with its filter-feeding activity dependent on the water current. The effect of the substrate type on growth was not significant. However, the substrate type did affect survival, with sandy substrates yielding in better survival than muddy ones.