The timing of energy allocation to reproduction in an important group of marine consumers

Organisms may energetically finance reproductive effort using energy stored prior to the reproductive period (termed capital breeders) or using energy acquired during the reproductive period (termed income breeders). The specific strategy used has implications for population dynamics as well as for the response to environmental variation. Crabs and other crustaceans have generally been assumed to be capital breeders. Here I demonstrate an experimental procedure used to determine whether crabs are capable of using an income breeding strategy. I then examine data from several published studies from a range of crab species across a broad phylogenetic spectrum that conducted similar experiments to look for evidence of income breeding strategy. I show that income breeding does occur in crabs, but that it appears to be taxon-specific. In particular, I show that income breeding occurs in two species from the family Portunidae, but fail to find evidence for income breeding in other taxa examined. This finding has a range of implications for this ecologically and economically important group of consumers, including implications for their response to human-induced environmental change, their response to fishing pressure, and best practices for aquaculture. The implications of breeding strategy in crabs likely depends on phylogeny (morphology) and ecology, both of which influence the space available for energy storage inside the carapace.