Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Virginia Institute of Marine Science


The purpose of this study is to obtain information for the formulation of artificial diets for larvae of the American oyster (Crassostrea virginica) and to test procedures related to presenting these diets to the oyster larvae. In order to determine the nutrient components usually provided in larval diets, biochemical analyses of lipids and fatty acids, proteins and amino acids and polysaccharide carbohydrates were performed on five algae species used as a food source for oyster larvae. These algae are Chlorella sp., Pyramimonas virginica, Pseudoisochrysis paradoxa, Pavlova (Monochrysis) lutheri and Isochrysis galbana. The biochemical analyses indicate that the nutritional value of the algal species was not correlated with the total lipid or carbohydrate content, but to the concentration of total protein of the algae. The major fatty acid components of the total lipids of the five species were the C12, C14, C16, and C18 saturated fatty acids and the C16 and C18 mono- and polyunsaturated acids. The total w6 fatty acids were found to be higher in some of the algae. The principal sugar components in the polysaccharide of these five algal species are glucose, mannose, ribose, xylose, rhamnose and fucose. The major constituent was glucose which accounts for 28 to 86% of the total carbohydrate. Mannose was usually the second most abundant carbohydrate component. In addition to the five algae mentioned above, the protein and amino acid composition of four other algal species, Nannochloris oculata, Dunaliella tertiolecta, Phaeodactylum tricornutum and Tetraselmis suecica were also investigated. The major free amino acid components were alanine, arginine, glutamic acid, lysine, proline, serine and taurine. The principal protein amino acids were alanine, aspartic acid, glutamic acid, glycine, leucine, lysine, proline, serine, threonine and valine. Two types of microcapsules, gelatin-acacia and nylon-protein, were tested for acceptability to and digestibility by oyster larvae. Gelatin-acacia and nylon protein capsules were fed to oyster larvae Crassostrea virginica. Larvae were observed to ingest and digest both types of microcapsules. It was found that both types of microcapsules supported growth of larvae. Results also indicated that microcapsule concentration affected growth rate.



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