Theses and Dissertations

Defense Date

6-2010

Document Type

Thesis

Degree Name

M.S. Marine Biology

Department

Oceanographic Center

First Advisor

Amy C. Hirons

Second Advisor

Alexander V. Soloviev

Third Advisor

Jonathan Shenker

Abstract

Copepods, minute crustaceans, are vital constituents of marine food web dynamics in tropical ecosystems. Ecologically, copepods provide the link between primary production and tertiary consumers. Changes in population structure and densities may impact ecosystem stability and production on small to large spatial scales. The present study examined the influence of the Florida Current on copepod population densities off the coast of Fort Lauderdale, Florida due to limited data in the area. Samples were collected during February and July 2007 at two locations, Stations A and B. Station A, dependent on current dynamics, fluctuated between the most western boundary and the inshore waters adjacent to the coast. Station B was typically located within the Florida Current showing great influence from the current’s physical factors. The current, acted as a physical barrier, entrapping species at near shore stations, increasing population densities by increased nutrient loads through upwelling and land runoff. The movement of the current inshore showed a greater resurgence of oceanic species at each station. However, the western edge of the current, acting as a barrier, yielded the lowest population densities overall and among all copepod orders. The decrease can influence food web dynamics and the prey availability to higher tertiary consumers. Population dynamics were ascertained by relative copepod densities identified to the lowest possible taxa and enumerated. Calanoid copepods were dominant in zooplankton samples, showing high instances of Calanus and Undinula, followed by Poecilostomatoida, highly represented by Corycaeus and Oncaea, and Cyclopoida. Poecilostomatoid densities were numerically important, where in some samples Corycaeus contributed to 42 % of overall copepod densities. Previous studies have led to their underestimation, due to gear selectivity and extrusion directly related to their prosome length. Diversity levels revealed an overall diverse habitat, typical of tropical environments. However, there was greater diversity in coastal waters as compared to the Florida Current which was only found oceanic species present.

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