Composition of eggs in relation to embryonic development and female size in giant crabs [Pseudocarcinus gigas (Lamarck)]

The size and composition of eggs from 22 giant crabs (Pseudocarcinus gigas) were monitored over 165 days to determine trends through embryogenesis. Egg composition was most stable during the early stages of embryogenesis so additional sampling (n=143) was conducted during this period to assess the effect of female size, sampling location (east and west Tasmania)and successive broods between moults, on egg composition. During embryogenesis, eggs increased in diameter and moisture content while organic dry mass declined. Total carotenoid and lipid content per egg did not change significantly, whereas protein declined (as ash-free dry mass per egg). This indicates that protein was used preferentially to lipid, which may be an adaptation to the deeper water habitat of P. gigas. Females with heavy and intermediate carapace wear were considered more likely to have produced previous clutches and they produced eggs with significantly less carotenoid. The eggs of larger females contained significantly more water, less protein and less carotenoid, whereas there was no effect on total lipid (P<0. 05). Although the effects of female size on egg composition were significant, the magnitude of the effect was small (highest for carotenoid, r2=0. 17). Consequently, it is unlikely that larval viability is affected, or that larger females contribute more to recruitment than predicted by fecundity.