DIETARY-EFFECTS ON OOCYTE YOLK-COMPOSITION IN CAPITELLA SP-I (ANNELIDA, POLYCHAETA) - FATTY-ACIDS AND STEROLS

In 1988, immature Capitella sp. I (initial biomass 80 μg dry wt) were raised on four diets: Gerber cereal, TetraMin fish food, Ulva sp., and benthic diatoms. After 2 wk of culturing different populations on these diets, eggs were dissected from gravid females, frozen and analyzed for fatty acid and sterol composition. Eggs produced by worms on different food types were discriminated by fatty acid composition in a principal component analysis (PCA), with 18:19, 18:2, 20:5 and 20:4 fatty acids showing the greatest differences between experimental groups. The sterol profiles of all eggs were dominated by cholesterol (cholest-5-en-3 β-ol) and cholest-5,24-dien-3 β-ol (>60%). A PCA of egg sterols discriminated between adult diets with cholesterol, 23,24-dimethyl-cholesta-5-en-3 β-ol, cholest-5,24-dien-3 β-ol and a C-29 stenol showing the greatest differences. In field populations of Capitella sp. I, oocytes produced at different times of the year may have different levels of lipids depending on their dietary availability during vitellogenesis. Variations in oocyte composition may influence larval growth and development and thus have an impact on population dynamics. Alternatively, variations in fatty acid and sterol composition of oocytes may allow us to identify the food resources utilized by this species. © 1990 Springer-Verlag.