Meeting Abstract

P2.158  Saturday, Jan. 5  Vertical swimming and diving behaviour of competent larval oysters (Crassostrea virginica) in turbulence WHEELER, J.D.*; ANDERSON, E.J.; HELFRICH, K.R.; MCGANN, B.J.; MULLINEAUX, L.S.; Woods Hole Oceanographic Institution (WHOI); Grove City College; WHOI; Grove City College; WHOI jwheeler@whoi.edu

Investigating settlement responses in the transitory period between planktonic and benthic stages of invertebrates helps shape our understanding of larval dispersal and supply, as well as early adult survival in seafloor habitats. Turbulence is a physical cue which has been shown to induce sinking and potentially settlement responses in mollusc larvae. In this study, we observed swimming behavior in competent larval eastern oysters (Crassostrea virginica) in a grid-stirred turbulence tank, with the following objectives: 1) to isolate and quantify the behavioural component of larval vertical velocity (relative to the surrounding flow) using particle image velocimetry, 2) to determine if larval vertical velocity varies with turbulence level, and 3) to identify a dive response and determine if it increased in frequency in highly turbulent flow. Interestingly, we found that oyster larvae continue to swim upwards even in levels of turbulent flow comparable to estuarine and coastal surf zone habitats. The dive response decreased significantly in frequency with increasing turbulence. We determined that it was critical to track larvae and flow simultaneously, and subtract the local flow, in order to quantify accurately the population-level responses in larval vertical velocity.