To track sea turtles, get DNA from the sand
The DNA “fingerprints” that sea turtles leave behind offer scientists a way to track the health and whereabouts of the endangered animals, say researchers. The study is the first to sequence sea turtles’ environmental DNA, or eDNA—genetic material shed as they travel over beaches and in water. “We wanted to test the boundaries of this technology, which hadn’t really been applied to sea turtles before and certainly not on sand,” says David Duffy, assistant professor of wildlife disease genomics at the University of Florida. Nearly all of the planet’s sea turtle species are endangered and face a multitude of threats, including warming temperatures, habitat destruction and degradation, disease, hunting, and pollutants such as plastics. “Some of these threats are quite new and even ones that existed for a longer time are getting worse,” says Duffy, who is based at the university’s Whitney Laboratory for Marine Bioscience and Sea Turtle Hospital.
eDNA techniques were originally developed to extract and analyze DNA from microbes in soil and water. A team led by Duffy and graduate students Jessica Farrell and Liam Whitmore created techniques that can identify the presence of green turtles, Chelonia mydas, and loggerheads, Caretta caretta—both endangered species—via DNA in a small scoop of sand or a liter of seawater. The methods could help scientists verify where sea turtles are living and how their range and numbers are shifting over time, Duffy says. “By optimizing eDNA practices for sea turtles, we had a much better success rate of identifying them in an area than with traditional survey methods,” Duffy says. The team could also ascertain sea turtle pathogens in eDNA samples, including the main virus that causes fibropapillomatosis, an increasingly common cancer that causes cauliflower-like tumors on sea turtles’ skin, eyes, mouth, and internal organs.
The next step in the research project will focus on conservation genetics—using DNA to capture a snapshot of how many individual animals live in an area and how genetically diverse they are, a crucial predictor in how they will weather threats, Duffy says. “You can say not only whether the species is present or absent, but you can potentially start to measure how many of those species are present, which is not easy to do for marine animals,” he says. Before testing eDNA methods in the wild, the team refined their techniques in the tanks and sand occupied by recuperating turtles at the Whitney Laboratory. “You don’t need to be a highly trained scientist to collect eDNA, which makes this technology a lot more democratic,” Duffy says.
Read full article at Futurity: Research News