Plasma proteomics of loggerhead sea turtles (Caretta caretta) stranded during red tide events for identification of diagnostic biomarkers

Celina Ceballos, Kathleen Rein

The Water School, Florida Gulf Coast University, 11098 Fgcu Blvd N, Fort Myers, FL 33965

Karenia brevis, better known as the Florida red tide organism, is a harmful marine dinoflagellate that blooms almost annually along the west coast of Florida. This organism produces the brevetoxins, a suite of potent neurotoxins that can cause serious health concerns for many species of wildlife, including sea turtles. The dinoflagellate cells and the brevetoxins can be transferred through the marine food web to reach carnivorous loggerhead sea turtle, causing significant impacts on various physiological systems including immune, nervous, and muscular systems of these turtles once exposed. Sea turtles stranded during red tide can be rescued, transported to rehabilitation facilities, and given palliative care with the ultimate goal of release back to the wild. However, there are no definitive diagnostic criteria for brevetoxicosis in sea turtles other than stranding and association with red tide, and often sea turtles experience delayed exposure multiple weeks after a bloom because of the long temporal scale of trophic transfer of toxins. Our hypothesis is that brevetoxicosis can cause alterations in protein abundance in the plasma of sea turtles, and certain proteins with significant differences in abundance can be used as diagnostic biomarkers. Plasma samples that were taken from red-tide exposed and healthy sea turtles were analyzed via bottom-up labelled quantitative liquid chromatography tandem mass spectrometry-based proteomics to identify such biomarkers. We were able to conclude that the abundances of multiple plasma proteins are significantly altered when exposed to the red tide for sea turtles. With predicted increases in severity and duration of red tide blooms due to climate change, the threatened status of the loggerhead sea turtle, and demonstration of plasma protein alterations after red tide exposure, this study can result in more accurate diagnoses and insights into mechanism-based treatments for wildlife with brevetoxicosis.