Larval release in a sub-euphotic zone invertebrate triggered by sinking phytoplankton particles

This paper reports field results showing that the larval release of the snow crab, Chionoecetes opilio , in a subarctic fjord is phased with the sedimentation peak of phytoplankton particles originating from the surface spring bloom, but with a lag of 2–3 weeks. Further laboratory experiments with egg-bearing females showed a significant induction of larval release when they were exposed to senescent cultures of different phytoplankton species, as opposed to controls and females exposed to fresh cultures. These results are interpreted and discussed in the context of possible strategies evolved by the snow crab to enhance its reproductive success. The field and laboratory evidence presented here represents the first instance indicating that phyto-detritus can act as a chemical cue for initiating and synchronizing reproductive activities in sub-euphotic invertebrates. Selection for control of larval release by downward flux of algal particles may be especially important for invertebrate populations in high-latitude areas, where the development of plankton communities shows a high level of seasonality.