Egg size and egg composition in polar shrimps (Caridea; Decapoda)
Egg volume and several aspects of egg nutrient content (dry mass, organic content, carbon and nitrogen content) were measured in eggs from five species of polar caridean shrimp (Crustacea; Decapoda): Chorismus antarcticus, Notocrangon antarcticus and Nematocarcinus lanceopes from the Weddell Sea (Antarctic), and Lebbeus polaris and Eualus gaimardii from Svalbard (Arctic). In Chorismus and Notocrangon (the only species where this was studied) there were significant differences in mean egg volume between individual females. The degree of variation in egg size within individual females varied (within-brood CV ranged from 8 to 20%), although the average variability was similar to the between-female variation (between-brood CV for mean egg volume 14%). In all species examined, measures of egg nutrient content were significantly correlated with egg volume, indicating that differences in egg size reflect real differences in investment per embryo. However, the relationship between egg dry mass and egg volume within species differed from that between species. The common slope for within-species analysis was 97 μg/μl(SE 24), whereas the slope for mean data from nine caridean species was 460 μg/μl (SE 22).