Abstract
The Florida red tide (Karenia brevis) is a harmful marine dinoflagellate that produces brevetoxins (PbTxs), potent neurotoxins that pose serious health concerns for many marine species, especially along Florida’s southwest coast. During red tide blooms, wildlife often strand likely due to toxicosis, and they can be rescued and receive palliative care at rehabilitation facilities for possible eventual release, but there are no diagnostic criteria for brevetoxicosis other than association with red tide, and characteristic neurological symptoms. Florida manatees (Trichechus manatus latirostris) are highly susceptible to brevetoxicosis as air-breathing marine mammals whose habitat range overlaps with K. brevis distributions. Sea turtles, including loggerheads (Caretta caretta) and Kemp’s ridleys (Lepidochelys kempii) are also especially susceptible to brevetoxicosis as air-breathing reptiles at high trophic levels who frequent southwest Florida waterways. Studying sea turtles offers challenges as all marine turtles are protected species and listed as either threatened or endangered according to IUCN, with few opportunities to collect samples from sick turtles found during an active red tide bloom. The red-eared slider (Trachemys scripta) is an invasive freshwater turtle species, and as a breath-hold diving turtle with physiology like that of sea turtles, it could act as a model organism to study the impacts of brevetoxin on sea turtles. Exposure to brevetoxins is expected to cause a cellular stress response in the plasma of sea turtles and manatees, and that response could be tracked and measured using the proteome. Plasma samples that were taken from captive, cold-stunned, red tide-exposed, and healthy free ranging manatees, along with sea turtles that were found during and not during a red tide bloom, were analyzed via bottom-up, labeled, quantitative, liquid chromatography tandem mass spectrometry-based (LC-MS/MS) proteomics to identify biomarkers for brevetoxicosis. Plasma samples were taken from PbTx-3-exposed and healthy captive red-eared sliders at Mote Marine Laboratory and were analyzed in the same way to attempt to find brevetoxicosis biomarkers. Unfortunately, the data from these samples proved to be challenging to analyze using traditional proteomics methods due to broken assumptions of normality after transformations. However, I was able to conclude that the abundances of multiple plasma proteins are significantly altered when exposed to the red tide blooms, captivity, and cold-stunning for manatees and when exposed to red tide blooms for sea turtles. With predicted increases in severity and duration of red tide blooms due to climate change, the threatened to critically endangered status of manatees, loggerhead, and Kemp’s ridley sea turtles, 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.