A new method of DNA analysis can help researchers determine populations of ocean creatures, including sharks, by identifying genetic markers found in their environment’s waters, according to research published this week in the journal, Science Advances.
The new technology can recover fragments of DNA from shark skin, excretions and blood in the water. Using samples taken from over 3,000 dives and 400 baited videos, Stefano Mariani, a professor and associate dean of research at the University of Salford, United Kingdom, and a team of researchers based in France, Australia, Polynesia, and the United States conducted traditional and environmental DNA surveys in New Caledonia, in the French South Pacific.
“EDNA has great potential for complementing traditional survey methods and improving species detection,” says Mariani. “It could lead to more efficient conservation strategies for threatened species.”
According to the results of the study:
Of the 26 species of shark known to inhabit the waters of New Caledonia, the eDNA method yielded 13 species from only 22 seawater samples. In comparison, only nine species were observed in 2,758 underwater visual census (UVC) samples, and data from 385 baited remote underwater video stations (BRUVs) also revealed only nine species. Of the 13 species identified using eDNA, six were not identified by either of the two traditional methods, further suggesting that those older techniques are underestimating diversity.
In fact, sharks were identified in 91 percent of the 22 samples taken for eDNA analysis, with two or more species found in 64 percent of these samples. UVCs identified sharks in only 15 percent of samples, and BRUVs identified them in 54 percent. Diversity was also lower using the traditional methods: UVCs detected more than one species in only 3 percent of samples, and BRUVs in only 23 percent.
“We have all been surprised by these results,” said FIU marine scientist Jeremy Kiszka, a co-author of the study. “It’s exciting to know how useful this tool is, particularly to monitor the presence of rarer and more elusive species, which potentially includes endangered species. We really hope to expand our efforts to identify critical habitats for endangered marine species using this technique.”
