Algal diets for broodstock maintenance of the doughboy scallop Mimachlamys asperrima (Lamarck)

The effect of monospecific algal diets on filtration rate (algal cells h-1) and fecundity of Mimachlamys asperrima was investigated. Filtration rates of seven algal species were monitored to indicate species preferences and to estimate maximum daily filtration rates. Cells of Chaetoceros calcitrans and Pavlova lutheri were filtered most rapidly; however, on a cell weight (mg h-1) and cell volume (μL h-1) basis, scallops filtered more Rhodomonas salina and Tetraselmis chui from the water column. Filtration rates when fed the diatom Chaetoceros muelleri were the lowest of the tested species, with a relatively low weight and volume of the algae filtered. Maximum filtration rates of the tested species were estimated to vary between 2.25 x 109 and 7.68 x 109 cells scallop-1 day-1. Filtration of algal species by M. asperrima varied in accordance with both scallop size and water temperature. Five of the seven algal species previously tested were then selected for use as monoalgal diets for female M. asperrima and fed for 4 weeks. Fecundity of scallops after this treatment did not necessarily reflect filtration rates, being greatest for scallops fed C. muelleri, which was significantly greater than that of the scallops fed C. calcitrans. Percentage development of eggs to D-veliger larvae did not differ in accordance with the maternal diet. A combined diet of C. muelleri, P. lutheri and Tahitian Isochrysis aff. galbana averaging ≃ 2.5 x 109 cells scallop-1 day-1 was found to be suitable for the maintenance and conditioning of M. asperrima broodstock in recirculating systems