Population biology

For over a decade, researchers at Harbor Branch Oceanographic Institute (HBOI)
have conducted surveys of the bottlenose dolphin (Tursiops truncatus) population of
Indian River Lagoon (IRL) in Florida. I have constructed a 4-stage population model
using the statistical program R. The model is used to conduct a viability analysis by
analyzing the relationship between birth, calf and adult survival rates. The power
analysis compares survey frequency to expected confidence intervals in estimating
abundance. The sensitivity analysis shows that the population is most sensitive to
changes in adult survival, followed by birth rate and calf survival. The model shows a
strong chance of viability over a 50 year time span. The population is vulnerable to long
periods of decline if birth, calf or adult survival rates fall below certain thresholds.
Overall, the model simulates the future impacts of demographic change, providing a tool
for conservation efforts.

The first of five chapters describe the study area and study species, including a short description
about the impetus for this research. The second chapter describes a unique hydrologic model for application
in tidal ecosystems. The second chapter represents new information on the effects of various abiotic and
biotic factors on foraging wading birds in this highly dynamic environment. The third chapter identifies
important factors affecting the abundance of foraging wading birds in intertidal environments. The fourth
chapter presents a study of the foraging habitat preferences of two wading bird species in intertidal
environments. The fifth chapter describes a conceptual model of wading bird foraging ecology and a
predictive model of foraging habitat in intertidal zones. The conceptual model captures the major drivers
and linkages between the abiotic and biotic variables thought to affect wading bird foraging abundance in
intertidal habitats. The conceptual model also identifies major knowledge gaps in our understanding of
foraging ecology of wading birds in coastal intertidal areas. The predictive model of foraging habitat is
meant to be used by resource managers, but its framework may be useful for ecological studies in general.
The final and sixth chapter provides a summary of all the major findings. Each chapter has been written so
as to be independent of the other chapters. As such, a full background, along with a discussion of the
relevance of the chapter's findings is provided for each chapter.

The Abacoa Greenway is a manmade artificial water system constructed in the late 1990s, and home to an array of aquatic flora and fauna. There has been no previous survey of the species residing in this area; therefore this will be a foundation for future samplings to compare to. The goal of this study was to compile a species list of fishes inhabiting the freshwater systems of the Abacoa Greenway Ranges IV and V, as well as a classification of exotic and native species inhabiting the area. A total of 11 species have been collected and identified between March 2007 and May 2008. Of these three species have been classified as exotic or introduced and the other eight as native species naturally existing in Florida.

Epidemic models help us predict the outcome of an epidemic. I will discuss and compare two simple epidemic models: a deterministic model implemented by a simple differential equation, and a stochastic model, which is more realistic, but harder to analyze. In both models we assume, for simplicity, that each individual goes through only two stages: healthy (susceptible) and sick (infective). Such models, called SI epidemic models, describe infections with no immunity. We will show that, when the population gets large, the more realistic stochastic model approaches the simple deterministic model on the average, which will allow us to see that the deterministic model is used for a good reason.

Freshwater marshes are a harsh wetland ecosystem classified by seasonal water level fluctuation. Dry down periods are common in some marshes, making life difficult for fish and other aquatic organisms. The goal of this study was to compile an updated species list of fishes inhabiting the freshwater marsh system within Savannas Preserve State Park. Twenty-three fish species were collected between August 2005 and May 2007. This survey, along with past collections, and the current species list in the park's management plan were used to make a new proposed species list. Three species of nonnative fishes were observed during the study, the first report of exotic fishes in the park. It is believed that abnormally high water levels for an extended period may have allowed the water in neighboring canals to connect to the marsh system and, as a result, new species were able become introduced in the park.