Date of Graduation

Spring 2018

Document Type

Honors Research Project

Degree Name

Bachelor of Science



Research Sponsor

Anne Wiley

First Reader

Randall Mitchell

Second Reader

Peter Niewiarowski


The Florida Manatee (Trichechus manatus latirostris) is a threatened species that primarily feeds on marine and estuarine seagrasses. Over the past several years, the seagrass coverage in the Indian River Lagoon has varied due to human influence and algal blooms. This led to an unusual number of manatees dying and potentially, to remaining manatees shifting their diets. It can be difficult to decipher why or how diets shift, however, creating a timeline using stable isotopes can help address this challenge. Red blood cells from live Florida Manatees were analyzed for stable carbon, nitrogen, and sulfur isotope ratios. All samples were collected during the winter months of 2011-2015. These samples were analyzed with the goal of examining relationships between the isotope ratios (diet) of the manatees, seagrass coverage, and BCI% over time. All three isotopes were significantly correlated with one another. There was also a clear relationship between the seagrass coverage and isotope ratios each year. It is possible that the density of epiphytes on the seagrass plays a role in manatee health because BCI% was at a high when manatees were primarily feeding on seagrasses, but generally low when seagrass coverage and presumably, seagrass epiphyte density increased. The data from this project increase our understanding of the complex diet-isotope relationship in manatees.