Maternal effects in marine decapod crustaceans

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Mothers of many invertebrate species exhibit behaviours that are thought to improve the survival of their offspring and that are collectively called maternal effects. Mothers may make bigger eggs, invest more energy in individual eggs, oviposit at different times, incubate their eggs, protect the hatchlings from predators, or even feed the newly hatched offspring with trophic (nurse) eggs. While some of these behaviours are clearly adaptive (e.g., hatchling care and nurse eggs), the value of others (e.g., egg size and oviposition time) for increasing offspring survival is still open to debate and may differ among species. The proposed research program will explore maternal effects in three marine decapod crustaceans. The three species were selected for their economic and ecological importance, but also for their contrasting life-history and ecological features. Notably, the snow crab and American lobster have larval dispersal phases that are respectively long (months) and short (weeks), while the sculptured shrimp has extended maternal care with hatchlings remaining on females until the juvenile stage. The laboratory and field studies that constitute this research program will focus more specifically on the maternal-offspring size relationship, on the timing of oviposition and hatching as they relate to mother's size and age, and on the intriguing possibility that the sculptured shrimp has trophic eggs. The research will assess the benefits of larger eggs, of early versus late hatching, and of trophic eggs on the growth and survival of offspring. This research has basic value in contributing to establish the diversity of reproductive strategies among decapod crustaceans; it also applied value in providing information that is important for the proper management of some of Canada's most important fishery resources.