Biophysical coupling between turbulence, veliger behavior, and larval supply
Fuchs, Heidi L.
MetadataShow full item record
LocationBarnstable Harbor, Mass.
The goals of this thesis were to quantify the behavior of gastropod larvae (mud snails Ryanassa obsoleta) in turbulence, and to investigate how that behavior affects larval supply in a turbulent coastal inlet. Gastropod larvae retract their velums and sink rapidly in strong turbulence. Turbulence-induced sinking would be an adaptive behavior if it resulted in increased larval supply and enhanced settlement in suitable coastal habitats. In laboratory experiments, mud snail larvae were found to have three behavioral modes: swimming, hovering, and sinking. The proportion of sinking larvae increased exponentially with the turbulence dissipation rate over a range comparable to turbulence in a tidal inlet, and the mean larval vertical velocity shifted from upward to downward in turbulence resembling energetic nearshore areas. The larval response to turbulence was incorporated in a vertical advection-diffusion model to characterize the effects of this behavior on larval supply and settlement in a tidal channel. Compared to passive larvae, larvae that sink in turbulence have higher near-bed concentrations throughout flood and ebb tides. This high larval supply enables behaving larvae to settle more successfully than passive larvae in strong currents characteristic of turbulent tidal inlets. A study was conducted at Barnstable Harbor, MA to estimate the responses of larvae to turbulence in the field. Gastropod larvae from different coastal environments had genus-specific responses to turbulence, suggesting that larvae use turbulence for large-scale habitat selection. On ebb tides, mud snail larvae had a similar response to turbulence as in the laboratory, with greater sinking velocities in strong turbulence. Behavior estimates differed for flood and ebb tides, indicating that additional physical cues influence behavior. Turbulence-induced sinking behavior would enhance retention and promote settlement of mud snail larvae in habitats like Barnstable Harbor.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2005
Showing items related by title, author, creator and subject.
Walsh, David (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1992-04)A pair of simple models representing the interaction of a continuously stratified f-plane quasigeostrophic lens with a uniform external shear flow is examined. The study is motivated by the desire to understand the ...
Bunker, Andrew F.; Haurwitz, B.; Malkus, Joanne Starr; Stommel, Henry M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1949)The observations presented and discussed in this paper were obtained as part of a research project conducted under contract NObs-2083 with the Bureau of Ships of the U. S. Navy by the Woods Hole Oceanographic Institution. ...
Involvement of Cytochrome P450 1A in the toxicity of aryl hydrocarbon receptor agonists : alteration arachidonic acid metabolism and production of reactive oxygen species Schlezinger, Jennifer J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1998-08)Two cytochrome P4501A-dependent mechanisms of aryl hydrocarbon receptor (AhR) agonist toxicity were examined in the marine teleost scup (Stenotomus chrysops), alteration of arachidonic acid (AA) metabolism and production ...