Identifying potential prey of the pelagic larvae of the spiny lobster Jasus edwardsii using signature lipids.

Signature lipid analyses were used to identify the natural prey of the pelagic phyllosoma larvae of the spiny lobster Jasus edwardsii. Lipid class, fatty acid and sterol composition were determined for associated potential prey items and for phyllosomes captured between 50 and 90 km offshore from the northeastern coast of New Zealand. Phospholipid was the dominant lipid class in all potential prey items and the transparent phyllosomes. The levels of other lipid classes varied between potential prey items, with the next most abundant classes being triacylglycerols, free fatty acids and sterols. A limited number of the potential prey items also contained wax ester. Major fatty acids in all potential prey items were generally 22:6omega3 (docosahexaenoic acid), 16:0, 18:1omega9c, and 20:5omega3 (eicosapentaenoic acid). Multivariate analyses of fatty acid and sterol content of the samples grouped the phyllosoma samples together regardless of their developmental stage or their collection location. However, the phyllosomes were not associated with any of the general groupings of pelagic ascidians, amphipods, chaetognaths, pteropods, euphausiids, fish, copepods or particulate matter that were formed by the statistical analyses. Although the sterol profiles of the potential prey items showed considerable variation, the phyllosomes contained predominantly cholesterol, suggesting that other dietary sterols are converted to cholesterol or metabolised by the phyllosomes. Therefore, the use of sterols for tracing the prey of J. edwardsii phyllosoma appears to be limited. Our results suggest that phyllosomes are opportunistic predators that feed on a variety of prey and are preferentially retaining specific diet-derived fatty acids.