Our last year of photo-ID surveys in Pensacola Bay is complete and our remote biopsy sampling begins! This year marks the beginning of the second half of my dissertation research assessing genetic population structure and connectivity between inshore and coastal bottlenose dolphins in the Florida Panhandle.
Sampling for the first half of my dissertation project has come to a close, with our last photo ID season that finished up in May of this year. Sampling over the past two years has resulted in seven seasons of mark-recapture photo-ID data that will allow us to determine seasonal abundance, obtain an estimate of the number of year-round residents in the area, and provide us with baseline estimates of vital population information, such as reproductive rates and success, and survival estimates. While most of the data processing and analyzing are ongoing, the data from our first summer season (2013) have been analyzed to give us an initial average abundance estimate of 195 dolphins (with a standard error of 45) in Pensacola Bay. We don’t yet know how many of these may be long-term residents or dolphins that simply pass through, however the data from subsequent seasons will help answer these questions.
Last year we reported on a historical flood that occurred in Pensacola in the spring of 2014, resulting in an outbreak of dolphin skin lesions. With the help of undergraduate student volunteers, we’ve characterized the types of lesions seen and measured the prevalence (proportion of the population with skin lesions) and extent (proportion of the dorsal fin covered with lesion(s) per individual) of those lesions over the subsequent seven months. Prevalence of lesions in the population increased from 27% to 40% by late fall 2014, but the average extent of lesions on individual animals decreased from 20% to 12% coverage over the same time period. It’s possible that lesions were caused by multiple factors and the initial outbreak reduced over time but left dolphins with a compromised immune system vulnerable to accumulating lesions from bacteria and/or toxins still present in the bay system. Since our data were based purely on visual observations, it is impossible to know the cause of lesions and how they might have affected individual health.
We documented that at least one calf did not survive the flood and three more are presumed dead. Of the 21 calves that were born in 2014, eight are known to have survived their first six months of life and 12 remain unknown since their mothers have not yet been seen again. This year, the first calving season since the flood, only five calves were born, which is a drastic difference from the 21 seen last year. Without historical trends on reproductive rates for this population, we can’t conclude that this is a direct result of the flood, since rates vary naturally from year to year. It is, however, an important cautionary note and we aim to conduct additional surveys next spring to monitor this trend over time.
Finally, this year marks the onset of the second half of my dissertation project which is aimed at determining genetic population structure and connectivity between inshore and coastal areas in the Florida Panhandle. We conducted our first week of sampling in July of this year, using well established remote biopsy sampling techniques and collected a total of 23 skin samples from the inshore Pensacola Bay population. Additional sampling is planned for next year to increase the number of samples we have and to start sampling the coastal area.
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. Thank you to the numerous interns and volunteers that have helped over the past couple years and to Steve Shippee, Reny Tyson, Jeremy Kiszka for volunteering their time to help me sample this summer!
This article appeared on page 22-23 in the December 2015 issue of Nicks n Notches.