Publication Date

2015-07-30

Availability

Open access

Embargo Period

2015-07-30

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Applied Marine Physics (Marine)

Date of Defense

2015-06-25

First Committee Member

Maria J. Olascoaga

Second Committee Member

Larry Brand

Third Committee Member

Harry DeFerrari

Fourth Committee Member

Alexander Yankovsky

Abstract

The most frequent and intense harmful algal blooms caused by the toxic dinoflagellate Karenia brevis occur on the West Florida Shelf. Causes of these blooms remain poorly known, including environmental conditions during their occurrence. Here the position of the Loop Current, freshwater discharge, and along- and cross-shore wind are analyzed using both real and modeled data. A spectral analysis shows several common spectral peaks at frequencies less than one cycle per 2.5 years, one cycle per year, and one cycle per 6 months with the real data, and one cycle per 2.5 years, one cycle per 9 months and one cycle per 8 months with the modeled data. A statistical analysis where persistent periods of no bloom and large blooms were separated from the real data, and persistent periods of high retention and low retention for the modeled data was also performed. A two-sample unequal variance T-Test analysis of the real data reveals that the difference between periods of large blooms and periods with no bloom are statistically significant to the 90% confidence level for the Loop Current’s position. A T-Test analysis of the modeled data reveals similar trends but with some differences that are explained by some slight inaccuracies in the models ability to predict the Loop Current’s northern position. Periods of large blooms are found to occur only when the Loop Current is in its northern position when the retention on the shelf is high, allowing a bloom to persist.

Keywords

Karenia brevis; West Florida Shelf; Loop Current

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