LARVAL RELEASE IN A SUB-EUPHOTIC ZONE INVERTEBRATE TRIGGERED BY SINKING PHYTOPLANKTON PARTICLES

This paper reports field results showing that the larval release of th e 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 o f larval release when they were exposed to senescent cultures of diffe rent 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 it s reproductive success. The field and laboratory evidence presented he re represents the first instance indicating that phyto-detritus can ac t as a chemical cue for initiating and synchronizing reproductive acti vities in sub-euphotic invertebrates. Selection for control of larval release by downward flux of algal particles may be especially importan t for invertebrate populations in high-latitude areas, where the devel opment of plankton communities shows a high level of seasonality.