GROWTH OF CORBICULA-FLUMINEA (BIVALVIA) FED ARTIFICIAL AND ALGAL DIETS

Laboratory experiments were conducted to assess the growth of Corbicula fluminea Muller (1774) fed mixed diets of the green alga Ankistrodesmus and five artificial foods (nine-grain cereal, rice flour, rye bran, denatured brewer''s yeast and Ralston Purine trout chow). Clams lost weight after 30 days on each artificial diet; however, weight losses were significantly less than those of control clams which were not fed (p < 0.05). In contrast, clam growth was positive in each treatment which included Ankistrodesmus. There was no significant difference in the tissue growth of clams fed on an Ankistrodesmus monoculture and Ankistrodesmus supplemented with each artificial diet (p > 0.2). Therefore, we conclude that all of the artificial diets evaluated were of nutritional value. However, the alga Ankistrodesmus appears to be a superior food item. In subsequent experiments, clams were fed on diets consisting of various combinations of six genera of green algae (pedinomonas, Ankistrodesmus, Chlamydomonas, Chlorella, Scenedesmus, and Selenasrum). All trialgal combinations of Chlamydomonas, Chlorella, Scenedesmus, and Ankistrodesmus and a dialgal culture of Chlamydomonas and Chlorella resulted in strong positive tissue growth. No other dialgal or monoalgalculture resulted in similar growth. Cultures of Selenastrum were found to be toxic, and their filtrate was determined to inhibit Corbicular filtration.