Temporal and Spatial Distribution of Manatees in Kings Bay, Crystal River, Florida

Abstract

The distribution of the manatee (Trichechus manatus) in Florida is seasonally influenced by changes in ambient temperature (Moore 1951, Hartman 1974:8-9, Shane 1983). During spring and summer, manatees are widely dispersed along the Gulf and Atlantic coasts of the Florida peninsula (Hartman 1974:205-206, Powell and Rathbun 1984). In autumn, manatees migrate southward and are attracted to warmwater discharges where water temperatures remain 20 C or higher throughout the winter (Hartman 1974:13; Powell and Waldron 1981; Shane 1983, 1984). Although most warm-water refuges used by manatees in Florida involve thermal effluents from industrial plants, 6 of the 25 known sites are natural artesian springs (Hartman 1974:13). The largest manatee aggregation at a natural refuge occurs in Kings Bay, at the headwaters of the Crystal River on the Gulf coast of north-central Florida (Hartman 1974:18-19). The number of manatees wintering in Kings Bay appears to have increased since the 1960's (Powell 1981), as has human use of the bay. Diving, boating, aquatic weed control, dredging, and construction have intensified to the point where conflicts with manatee conservation now exist. The objective of this study was to obtain baseline data on seasonal changes in the distribution and abundance of manatees in