Optimization of hatchery culture of the sea scallop, Placopecten Magellanicus (Gmelin,1791) : dietary lipid quality and fatty acid requirements

Feindel, Scott C. (2000) Optimization of hatchery culture of the sea scallop, Placopecten Magellanicus (Gmelin,1791) : dietary lipid quality and fatty acid requirements. Masters thesis, Memorial University of Newfoundland.

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Abstract

Different species of live algal cultures varying broadly in essential fatty acid content - eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3), and arachidonic acid (ARA; 20:4n-6) - were used in exploratory experiments to evaluate the impact of dietary lipid quality on broodstock conditioning and larval culture of the sea scallop (Placopecten magellanicus). Egg biochemical composition was relatively stable when diets were fed to animals in a partially conditioned state, but varied more for wild eggs compared to lab-conditioned animals. When diet treatments were initiated earlier in a second experiment, differences among the fatty acid composition of gonad samples were more apparent. -- In larval feeding trials, fatty acids in neutral lipids, and to lesser extent phospholipids, of larvae reflected the composition of the algae they were fed. C₂₀ and C₂₂ PUFA were preferentially accumulated, particularly DHA which plays a specific structural role in Pectinids. Growth results suggest increasing dietary ARA, or possibly 22:5n-6. -- Last, variability in lipid quality was examined in aging batch cultures of a strain of Pavlova sp. (CCMP459). Lipid, mainly TAG, as a proportion of dry weight, more than doubled over the experimental period. As cultures aged, the (n-3)/(n-6) series fatty acid ratio was reduced. By controlling algal harvest strategies or culture conditions, the biochemical composition of algae may be optimized to best meet the nutritional needs of a particular bivalve species or developmental stage.

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