Title

Living on the edge of the Florida current: A study of the physical processes affecting primary production and larval transport

Date of Award

2007

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Christopher N. K. Mooers, Committee Chair

Abstract

Regional (ca. 1000 km) and local (ca. 100 km) scale, three-dimensional, time-dependent, coastal ocean circulation models, coupled with lower trophic level ecosystem and Lagrangian larval transport models, have been implemented for the East Florida Shelf (EFS) with sufficient horizontal and vertical resolution to admit the dominant physical and biological processes, and to conduct model-observations comparisons. Consequently, the results provide reliable new information about the impact of the variable Florida Current (FC) circulation on physical and biological processes over timescales ranging from daily to seasonal. At the regional scale, simulations with a mesoscale-resolving (ca. 4 to 10 km) coupled ocean circulation-ecosystem model provide estimates of the frequency, intensity, duration, and property transport of upwelling events along the EFS, and help identify their underlying mechanisms. North of 27°N, FC meanders and FC frontal eddies (FCFE) are the main contributors to the mesoscale variability. FCFE events also impact primary production at the shelfbreak, resulting in short-lived phytoplankton blooms with large amplitude variations on weekly and monthly timescales. At the local scale, simulations with a high-resolution (ca. 800 m) ocean circulation model, combined with targeted in-situ observations, provide estimates of alongshelf and cross-shelf transport of larval marine organisms along the Upper Florida Keys. For AUG 2006, alongshelf advection was mainly poleward and due to the subtidal flow of the FC, while cross-shelf advection was mainly onshore and due to wind-driven currents. Typical advection distances were of the order of 10 to 50 km for pelagic larval durations of ca. one week. Probability density functions indicated a significant onshore transport component, thereby suggesting that local retention was probably the dominant mechanism supplying coral larvae to the reefs on a weekly timescale. Overall, the results set the stage for future ecological forecasting efforts in the EFS region, including the implementation of more complex ecosystem and Lagrangian larval transport models. By identifying the spatial and temporal scales at which physical and biological processes occur along the EFS, the validated simulations also provide a rational framework for improving the design of coastal ocean observing systems.

Keywords

Physical Oceanography; Biology, Oceanography

Link to Full Text

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