EFFECTS OF RED TIDE ON SEA TURTLE NEST SUCCESS IN SARASOTA COUNTY, FL

Exposure to red tide (Karenia brevis) in varying quantities has been known to affect the wellbeing of numerous species in a variety of ways. In sea turtles, prolonged exposure can lead to extreme detrimental impacts on muscular, neurological, and immune function, resulting in death as well as sublethal conditions. While these direct effects are well studied, less is known about how K. brevis uptake by nesting females can affect nest success. 

Hatching success and emergence success rates of loggerhead (Caretta caretta) & green (Chelonia mydas) sea turtles from 2007 to 2022 across 5 beaches in Sarasota County, FL were compared with the county’s historical K. brevis data over the same period to determine the effects of red tide in embryonic development. Hatch and emergence success were not normal for both species and their residuals were not normal. In relation to red tide levels, hatch and emergence success of loggerhead turtles showed significant differences. Results were split for green sea turtles: hatch success was not significant when compared to red tide levels but emergence success was.

Although significant, these simple models are likely hiding the real answer. Embryonic development should be affected by ingested brevetoxins that were stored in lipid reserves. However, there is no way to guarantee that is what’s happening here. Future research should focus on nesters and their nests during red tide blooms. Eggs should be staged to determine if/when development was arrested. Timing of blooms in relation to the nesting season may also explain the variance. 

For more information contact ambailey1@eckerd.edu