The Pensacola Bay system, in the Florida panhandle, has a history of anthropogenic disturbances.
Toxins were entering the system as early as the 1800s in association with a prominent logging industry. Since then, the ecosystem has been exposed to a major chemical spill, several red tide events (producing a biotoxin), increasing pressures associated with coastal development, and most recently, the Deepwater Horizon oil spill.
Unfortunately, very little is known about the size or stock structure of bottlenose dolphin populations in the Northern Gulf of Mexico such that our ability to evaluate threats is limited. Vessel-based surveys from an ongoing project in neighboring Choctawhatchee Bay (to the east) were expanded in 2010 to explore lower Pensacola Bay.
The initial results provided evidence for a substantial bottlenose dolphin community for which no previous baseline population information existed. My PhD research is expanding on this initial work to (1) provide the first population assessment for the entire Pensacola Bay system and (2) to explore population structure of dolphins between inshore, coastal and neighboring systems. I am also exploring the utility of combining genetic and stable isotope (a type of biomarker using natural elements like carbon and nitrogen) data to examine stock structure at varying spatial scales.
I am in the early phases of my research, having completed my first field season this summer. I am currently using mark-recapture techniques to estimate seasonal variation in dolphin population abundance. This process involves ‘marking’ individuals by taking photographs of the natural dorsal fin markings and ‘recapturing’ them over time. The proportion of ‘marked’ animals that are re-captured is used to estimate the total population. The survey area consists of the inshore bay systems (Pensacola, Escambia, East, and Blackwater Bays) and a coastal zone. A single mark-recapture session entails surveying the entire inshore system three times (3 days each), separated by two days each to allow the population to ‘re-mix.’ From June-August, my volunteers and I surveyed for 172 hours, completing 22 surveys which resulted in 84 dolphin sightings. We are in the beginning phases of processing data from this effort but have catalogued over 50 animals from our first eight days on the water so far.
Data from this project will also be used to examine distribution and site fidelity patterns, to develop a sighting history catalog for incorporation into the GoMDIS catalog, to track individuals over time, and to compare to data from Choctawhatchee to determine whether the Pensacola system is home to a group of distinct local residents. This research has been supported by funding from the UCF Physiological Ecology and Bioenergetics Lab, the UCF Arnold Haverlee Exploration Endowed Scholarship, and a charitable donation from Frank Toms. The project wouldn’t have been possible without the help of Diana Bateman, Brittany White, and several other undergraduate volunteers.
This article was published on pages 6-7 in the January 2014 Nicks n Notches.