Correlation between transport and moulting of catadromous crab megalopae: The effects of starvation on rhythmic vertical migration

Adopting circatidal vertical migration, catadromous crab megalopae use flood tide transport (FTT) to reach the settlement or nursery habitat and moult at a high rate that mismatches the low food-availability en route. To explain this "mismatch problem," we hypothesize that besides development, starvation also affects megalopae's transport so that the starved ones with low moulting possibility cannot succeed migration. The hypothesis was tested by studying how starvation affected rhythmic vertical migration of Chinese mitten crab (Eriocheir sinensis) megalopae. The findings support our hypothesis by showing that starvation weakened the vertical migration of the megalopae. The results also revealed that starvation caused the residual vertical migration of the megalopae to follow a circadian rhythm in addition to circatidal rhythm. We conclude that for catadromous crab megalopae, transport, just as development, is controlled by nutrition; and there exists a trade-off between the development and transport of Chinese mitten crab megalopae .