HCNSO Student Theses and Dissertations

Defense Date

1-11-2010

Document Type

Thesis

Degree Name

M.S. Marine Biology

Department

Oceanographic Center

First Advisor

Edward O. Keith

Second Advisor

Curtis M. Burney

Third Advisor

Allan D. Sosnow

Abstract

The diurnal movements of Florida manatees (Trichechus manatus latirostris) in warmwater refugia are poorly understood and these may prove critical in accurately estimating populations of these animals. Previous studies indicate that manatee populations in such refuges in Tampa Bay, FL, peak mid-day and decline towards evening when the animals leave to forage. This trend suggests that variation in the timing of aerial manatee population surveys may hamper accurate estimation of the true population size. Aerial survey counts are known to underestimate population size, yet the extent of the underestimation may be greater than expected. In this study data were collected over three seasons from land-based surveys monitoring the presence of manatees in the effluent canal from the Florida Power and Light electricity generating facility in Port Everglades, FL between 15 November and 31 March. My findings indicated there was no significant difference in the number of manatees observed during the seasons studied despite a significant difference in ambient water temperatures. There was a significant correlation in the number of manatees an observer can expect to see based on time of day with the trend indicating there are higher numbers of observable manatees in the morning compared to later in the day. This suggests that early morning aerial counts will more accurately reflect true manatee presence in the Port Everglades power plant. Photographs of individual manatees yielded a total of 58 animals with unique scaring patterns.

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