THE EFFECTS OF DIETARY FATTY-ACIDS ON THE FATTY-ACID COMPOSITION OF THE HARPACTICOID COPEPOD, TISBE SP, FOR USE AS A LIVE FOOD FOR MARINE FISH LARVAE

The marine harpacticoid copepod Tisbe sp. was isolated from plankton c ollected near Halifax, Nova Scotia and raised in the laboratory for ov er 20 generations. The effects of feeding various algal (Chaetocerus c alcitrans, Dunaliella tertiolecta, and Isochrysis galbana) and baker's yeast diets on the nutritional value, or essential fatty acid (EFA) c omposition, of the copepod for use as an alternative live food for col d-water marine finfish larvae was evaluated in this study. The copepod was able to synthesize a significant amount of the EFA's, 20:5n - 3 ( EPA) and 22:6n - 3 (DHA) from shorter chain n - 3 polyunsaturated fatt y acids, when fed the algae D. tertiolecta (6.2% EPA, 12.4% DHA) or ba ker's yeast (12.4% EPA, 28.4% DHA) which are deficient in these EFA's. The copepod also maintained a consistently high DHA:EPA ratio (> 2) w hen fed each of the dietary treatments. (C) 1998 Elsevier Science B.V. All rights reserved.