Metamorphosis of Larval Slippershells, Crepidula plana, in Response to Jet-Stirred Turbulence

Planktonic larvae that settle and metamorphose into benthic adults on the seafloor rely on indicators to select appropriate settlement environments. These cues help to determine the dispersal, distribution, and connectivity of marine populations and are crucial to understanding the ecology of benthic organisms. We study turbulence as a potential broad-scale indicator of suitable settlement environments for coastal species. In our current study, we investigated larval response of the eastern white slippershell Crepidula plana to turbulence generated in a newly developed jet-stirred tank over a range of ecologically relevant energy dissipation rates characteristic of still water to intertidal surf habitats. The jet-stirred tank generates turbulent flow that is nearly isotropic and homogeneous, reflective of coastal environments. Flow properties, including dissipation rates, are estimated using particle image velocimetry. Larvae exhibiting morphological signs of competence were exposed to turbulence in the tank for 15 minutes, then removed and observed for metamorphosis over 19 hours in response to KCl. We observed that very few larvae (typically <10%) metamorphosed; although there was a slight increase in percent metamorphosis in turbulence compared to still water, the difference was not statistically significant. These results suggest that short-term exposure to turbulence does not have a strong influence on the metamorphosis of C. plana larvae at this stage. However, a concurrent study of the same population of larvae, comparing larval responses between still and continuously stirred culture conditions, showed a trend of enhanced growth and increased metamorphosis in stirred containers. Future work is planned to investigate the effects of sustained turbulence on behaviors and metamorphosis of these larvae at different stages in their development.