Traces of DNA Found in the Ocean Led to the Discovery of Species That Were Thought to Be Missing
The latest underwater mission has paved a new way for discoveries. Traditional methods like fish nets, underwater cameras were unable to scour unexplored areas, a gap that the recent study, led by Loïc Sanchez, tried to fill. The study used traces of genetic material in seawater, and the findings were surprising. The result proved the existence of many marine species that were once presumed to be extinct or missing. This discovery made scientists realize the lack of knowledge about biodiversity in marine ecosystems and that the current methods of underwater research aren't entirely efficient. According to the study published in the journal PLOS Biology, scientists used traces of genes in the seawater to study hidden patterns in biodiversity.
The researchers gathered around 1,000 water samples from polar seas to remote tropical islands. They collected environmental DNA, aka eDNA, released by organisms into water, soil, or air, which allows scientists to detect the species without physically having it or its photograph. Sanchez, a researcher at the University of Montpellier (UM) and CNRS, led the research that focused on species distribution. “Our eDNA surveys showed that known geographic ranges for 93% of species and ecological niches for 7% were underestimated,” Sanchez said, as per earth.com.
This means that the current mapping system of underwater biodiversity isn't effective in recording all the species within. For example, the crocodile icefish has always been associated with the freezing weather conditions of the Antarctic region. However, the species was discovered in Patagonia, South America. The Large-scale Mullet was also oddly discovered off the coast of the island of Corsica, suggesting a hidden long-range colonization in the Mediterranean Sea. “A machine learning model predicted that just 10 eDNA samples could reveal about 24 new fish species on average, and up to 98 in unsampled tropical areas," Sanchez added.
These mismatches also highlight how some species were underestimated and were presumed to be suitable in a certain living condition. While in actuality, they can sustain multiple weather conditions. Previous databases reflect areas where scientists and observers conducted the most research. Remote areas, the Arctic Ocean, Antarctic lands, and offshore are some of the common places of research bases. This pattern prevented the scientists from recording data in places where fish actually live. The recent study used the collected eDNA to spot gaps in the recorded database by comparing the species. They found that the environmental DNA filled research gaps and explored species from places that were never looked at in the past surveys. The genetic material also included samples of the shortfin mako shark near the Arctic Circle.
The study also helped find records for cryptobenthic, small reef fishes and dwellers who hide in crevices. These species were underestimated because divers and underwater footage were unable to spot them. The eDNA and the genetics of species living under water don't usually add up, and the difference is what turns into a benefit for scientists. Scientists believe that combining eDNA and traditional methods might help provide a bigger picture of the marine biodiversity. "Our results suggest that sampling in remote areas and performing eDNA surveys in over-sampled areas may both increase fish ecological niche ranges toward unexpected values with consequences in biodiversity modeling, management, and conservation," the scientists added.
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