The influence of vertical migratory behaviors on the transport of marine organisms Public Deposited

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  • March 21, 2019
  • Carr, Sarah
    • Affiliation: College of Arts and Sciences, Department of Marine Sciences
  • Many marine organisms are dispersed by water currents for all or part of their lives or utilize water currents to migrate between habitats as juveniles or adults. This transport is an important determinant of the distribution of marine populations and can be significantly influenced by organisms' vertical migratory behaviors (VMBs). The importance of VMBs to transport is now widely recognized, but there have been relatively few attempts to give detailed descriptions of them or quantify their influence. This dissertation describes and quantifies the influence of ebb-tide transport (ETT), a VMB in which crabs ascend into the water column during ebb tides, on the spawning migration of female blue crabs Callinectes sapidus, near Beaufort Inlet, North Carolina. Ovigerous female crabs were tracked with ultrasonic telemetry. A detailed behavioral model was developed from this study as well as other field and laboratory studies and was coupled to a hydrodynamic model of the Beaufort Inlet region. The total distances that crabs traveled during ebb tides ranged from 10 - 40 % of the distances that passive particles would have traveled under the same conditions. This dissertation also describes and quantifies the influence of diel vertical migration (DVM), a common VMB in which organisms reside in near-surface waters at night and at deeper depths during the day, on the transport of zooplankton in a coastal region with strong iii seasonal upwelling. Simple behavioral models of zooplankton DVM were coupled to a hydrodynamic model of the Monterey Bay region of California. DVM reduced transport away from the region by as much as 8 km d-1 relative to passive transport near the surface. A synthesis of the existing literature supports the assumptions that selective tidal-stream transport behaviors such as ETT enable directed migrations in estuarine and coastal regions while DVM and ontogenetic vertical migrations generally retain organisms near their starting locations. The synthesis also demonstrated that quantification of the influence of VMBs on transport must be carried out for specific behaviors at specific locations because organisms' characteristic VMBs and hydrography vary widely between marine environments.
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  • In Copyright
  • Luettich, Richard A.
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  • University of North Carolina at Chapel Hill
  • Open access

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