SHORT TERM RECORDS OF MANATEE DIETARY PREFERENCES INTERPRETED FROM BONE AND TISSUE CHOLESTEROL d13C VALUES
To determine whether the measurement of cholesterol d13C values can provide short-term dietary information for manatees, we have begun collecting tissue samples from recently deceased manatees from the Indian River Lagoon along the eastern coast of Florida. From each individual, 3 tissues differing in metabolic turnover rate were selected for analysis including liver (fast turnover), muscle (intermediate turnover), and bone (slow turnover). Cholesterol extracted from each of these tissues will have formed within different periods of time over the course of the year, providing sub-annual records of seasonal dietary patterns that can be interpreted from variations in cholesterol d13C values. Comparison of cholesterol isotope values with collagen values from the same individual will then provide a means to quantify the magnitude of seasonal dietary variation relative to long-term dietary preferences. By extending these analyses to recent and fossil material, future work could examine whether the feeding patterns of Florida manatees have changed significantly over time and, if so, whether human or environmental factors have contributed to this change.