ASSESSING DIFFERENT MONITORING TECHNIQUES FOR JUVENILE GREEN TURTLES (CHELONIA MYDAS) IN THE BAHAMAS
thesisposted on 27.04.2021, 17:45 by Laura Christine St Andrews
Sea turtles are integral components of many marine ecosystems. Green turtles (Chelonia mydas) are generally herbivorous, feed primarily on seagrasses, and are endangered in the Caribbean. The species utilizes extensive marine habitats for foraging and migratory routes, and because of its broad distribution, it is difficult to conduct population assessments. Here, I assessed commonly used techniques for monitoring green turtles in the wild. Specifically: (1) biopsy sampling for molecular assays and (2) unoccupied aerial vehicles (UAVs) deployment and boat-based surveys for population monitoring.
Skin biopsies are collected from sea turtles for a variety of molecular analyses; however, very little information exists on the natural healing rates at the site of the biopsy in the wild. In Chapter 2, I monitored the healing rates of 17 juvenile green turtles in Eleuthera, The Bahamas, for up to 488 d after taking a 6mm biopsy tissue sample. Complete tissue repair and maturation was observed after a year and a half, and there was no evidence of infection at any point during the healing process. While scarring persisted for several months, biopsy sampling had minimal long-term impact.
UAVs are increasingly being used to monitor marine megafauna. In Chapter 3, I evaluated the efficacy of using UAVs to detect sea turtles when compared to boat-based surveys. During UAV surveys, the UAV was flown along preprogrammed routes in four creek systems. A boat survey was conducted simultaneously on the same path. I used regression analyses for each survey type to assess the effects of environmental variables on turtle detection rates My results indicate that there were no statistically significant difference between the numbers of turtle detected via boat or UAV surveys; however, there were clear differences in the time and potential cost associated with either method.