Variation in the lipid content and composition of Antarctic krill Euphausia superba at South Georgia

Samples of Antarctic knll Euphausia superba Dana from 8 sites around South Georgia were analysed for total lipid and lipid class composition. Samples consisted predominantly of immature krill, and females were entirely absent from samples from 2 of the 8 sites studied Individual fresh mass varied from 0.16 to 1 72 g (median values of 0 47 g (0 16 to 0.94), 1 14 g (0.71 to 1.63) and 1.46 g (0.94 to 1.72) for immatures, males and females respectively). Lipid amounts varied from 5 to 147 mg ind."' (median values of 17.8 mg (5.1 to 64.2), 21.0 mg (9.3 to 87 7) and 70 3 mg (17 3 to 146 9) for immatures, males and females respectively) Triacylglycerol (TAG) and phosphatidylcholme were the 2 most abundant lipid classes in all krill. Multivariate analysis of lipid composition indicated significant over- lap between sex-maturity classes, although female kriU tended to be distinguished from males by higher proportions of TAG and lower proportions of phosphatidylserine plus phosphatidylinositol, Reproductive investment is implicated in the overall variability in lipid content and composition, with females containing high lipid levels as reserves for egg production, whilst males showed apparent lipid deficits resulting from short-term mobilisation of storage material for spermatophore production and attachment Significant and systematic site-to-site variability in hpid content and composition were evident in the samples and this could not be explained by the sex ratio or krill siz