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
Suggested CitationThesis: Fuchs, Heidi L., "Biophysical coupling between turbulence, veliger behavior, and larval supply", 2005-09, DOI:10.1575/1912/1710, https://hdl.handle.net/1912/1710
Showing items related by title, author, creator and subject.
Initial settlement of marine invertebrate larvae : the role of passive sinking in a near-bottom turbulent flow environment Hannan, Cheryl Ann (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1984-02)The hypothesis that planktonic larvae of benthic invertebrates sink through the water like passive particles in turbulent flows near the seabed was tested in the field using several groups of geometrically different ...
Jaroslow, Gary E. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1996-12)The objective of this Thesis was to interpret the structural development of slowspreading ridge segments by: 1) delineating the nature, magnitude, and relative importance of primary tectonic and volcanic processes that ...
Polcari, John J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1986-05)The dual issues of modal decomposition for tonal sound fields and the temporal coherence of the modal amplitudes are investigated for the case of the central Arctic sound channel at very low frequencies (15-80 Hz). A ...