Endangered sea turtles experience severe mortality during Florida red tides. This project uses non-endangered freshwater turtles as a model animal to determine the effects of Florida red tide on endangered sea turtles. Researchers expect project results to identify how red tide toxin gets into turtles, how long it stays, and the impacts on organs such as the lungs, muscles, and nervous system. Researchers also expect to develop new methods of treating toxin poisoning in turtles.
Why We Care
Karenia brevis, the “Florida red tide” organism frequently blooms in some areas of the Gulf of Mexico and produces a suite of nerve toxins (called brevetoxins). The toxins cause human respiratory illness along beaches and accumulate in shellfish, which, when consumed by humans, cause Neurotoxic Shellfish Poisoning. Severe blooms result in mass mortality of fish and a number of protected and endangered species. Among the species impacted are a variety of threatened and endangered marine turtles.
For example, in the severe Florida red tides of 2005 and 2006 at least 179 loggerhead sea turtles died, but other species may be impacted as well, including leatherback, green, hawksbill, and Kemp’s ridley sea turtles. Many turtles also strand on beaches and are taken to facilities for rehabilitation where some recover and are released back into the wild.
What We Are Doing
In this study turtles will be experimentally exposed to controlled toxin doses. Because such experiments cannot be conducted on endangered sea turtles, a non-endangered freshwater turtle, the slider (Trachemys scripta), will substitute for sea turtles to determine the toxin effects on critical turtle organ systems. As exposure in turtles may occur through ingestion and/or inhalation, with potentially different distributions, effects, and rates of metabolism, brevetoxins will be administered by both mechanisms. The uptake, excretion, and neurotoxicity of brevetoxin will be examined as well as the impact of brevetoxin on various organs systems and the immune system. Finally, the information will be used to develop methods of treating and rehabilitating endangered sea turtles suffering from toxin poisoning (called brevitoxicosis).
This is part of the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) program. The project leader is Dr. Sarah Milton, Florida Atlantic University, Department of Biological Sciences. Project partners include Leanne Flewelling of the Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Catherine Walsh and Deborah Fauquier of Mote Marine Laboratory, and Gregory Bossart of the Georgia Aquarium and Harbor Branch Oceanographic Institute.
Benefits of Our Work
Developing a live animal model that can demonstrate how brevetoxins cause illness and death in freshwater turtles will provide a sound scientific basis for treatment of sea turtles at the numerous rescue facilities that rehabilitate sea turtles in the Gulf Coast states.