Two liters of seawater, or about half a gallon. That’s all that’s needed to detect the presence of sharks in the ocean, according to a new study. A group of researchers from Florida International University (FIU), New College of Florida and Havenworth Coastal Conservation recently teamed up to develop a new method of detecting the presence of blacktip sharks (Carcharhinus limbatus) in Terra Ceia Bay, a semi-enclosed bay on the west coast of Florida.
Like all animals, including humans, sharks constantly shed DNA in bits of skin, mucus, blood and even poop, and these fragments of genetic material can provide vital clues to a shark’s whereabouts. “We detect whatever the animals leave in the environment,” lead author Bautisse Postaire, a postdoctoral researcher at FIU, told Mongabay. “You could detect everything, basically, except actual fresh tissue.”
Over a period of two years, the team took 58 water samples, and detected the presence of blacktips in 27 of the samples. The blacktip DNA was more abundant in the spring and summer, which is when they use the bay as a nursery. There was less DNA in the water in the fall, which is when the sharks start to leave the area. Demian Chapman, co-author of the study and associate professor in the department of biological sciences at FIU, said this eDNA technique is another useful tool in monitoring world shark populations, which are under threat due to a number of human activities, including overfishing, shark finning, and pollution.
Source: Mongabay
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