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Circulation Dynamics and Larval Transport Mechanisms in the Florida Big Bend

Title: Circulation Dynamics and Larval Transport Mechanisms in the Florida Big Bend.
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Name(s): Todd, Austin C., author
Chassignet, Eric, professor directing dissertation
Bourassa, Mark, university representative
Clarke, Allan, committee member
Coleman, Felicia, committee member
Dewar, William, committee member
Heuttel, Markus, committee member
Morey, Steven, committee member
Department of Earth, Ocean and Atmospheric Sciences, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: text
Issuance: monographic
Date Issued: 2013
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
Physical Form: online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The Florida Big Bend region in the northeastern Gulf of Mexico contains both spawning sites and nursery habitats for a variety of economically valuable marine species. One species, the gag grouper (Mycteroperca microlepis), relies on the shelf circulation to distribute larvae from shelf-break spawning grounds to coastal seagrass nurseries each spring. Therefore, identifying the dominant circulation features and physical mechanisms that contribute to cross-shore transport during the springtime may provide valuable insight into the variation of the abundance of this reef fish. The physical mechanisms by which cross-shelf movement is possible, and the pathways by which materials may be transported onshore are examined. More specifically, variable wind stress and the conservation of potential vorticity are investigated for their role in setting the net across-shelf transport, using a very high horizontal resolution (800—900 m) numerical ocean model. The simulations demonstrate that the mean springtime shelf circulation is set by the rectification of flow during northwesterly or southeasterly directed wind stress, and significant cross-shelf flow may be generated during winds from the northwest. The springtime flow is mostly barotropic and tends to conserve potential vorticity over time scales shorter than about 12 hrs. For longer time scales, the nonconservation of potential vorticity enables movement of particles inshore. Particle advection experiments demonstrate that a primary pathway exists south of St. George Island by which particles are able to reach the nearshore environment, and that preferred release locations for particles to successfully arrive inshore coincide with known gag spawning aggregation sites. The results provide, for the first time, a description of the mechanisms by which onshore transport is possible from gag spawning sites at the shelf break to seagrass nurseries at the coast.
Identifier: FSU_migr_etd-7630 (IID)
Submitted Note: A Dissertation submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Spring Semester, 2013.
Date of Defense: February 1, 2013.
Keywords: Coastal physical oceanography, gag grouper, larval transport, Numerical modeling
Bibliography Note: Includes bibliographical references.
Advisory Committee: Eric Chassignet, Professor Directing Dissertation; Mark Bourassa, University Representative; Allan Clarke, Committee Member; Felicia Coleman, Committee Member; William Dewar, Committee Member; Markus Heuttel, Committee Member; Steven Morey, Committee Member.
Subject(s): Earth sciences
Oceanography
Atmospheric sciences
Geophysics
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_etd-7630
Owner Institution: FSU