Researchers used environmental DNA (eDNA) from more than 900 seawater samples collected from polar to tropical regions to refine marine species distributions. They found that over 93% of detected species have larger geographic ranges than previously recorded. Notably, crocodile icefish DNA was detected near Patagonia in waters about 18°F warmer than Antarctic conditions. These findings improve the accuracy of range maps and support better-targeted conservation planning.
Forensic eDNA Reveals Ocean Species Live Farther—and Warmer—Than We Thought
Researchers used environmental DNA (eDNA) from more than 900 seawater samples collected from polar to tropical regions to refine marine species distributions. They found that over 93% of detected species have larger geographic ranges than previously recorded. Notably, crocodile icefish DNA was detected near Patagonia in waters about 18°F warmer than Antarctic conditions. These findings improve the accuracy of range maps and support better-targeted conservation planning.
13:20, 05.11.2025Environment
Forensic eDNA Reveals Broader Ranges for Ocean Species
The oceans are rich with life, but their vastness makes comprehensive biological surveys difficult. Traditional approaches—underwater cameras, visual surveys, and nets—miss many species, especially in remote or deep regions. Researchers are now filling those gaps by reading traces of life left behind in seawater: environmental DNA, or eDNA.
How eDNA works
Environmental DNA consists of tiny genetic fragments shed by organisms through mucus, feces, gametes, or sloughed cells. Scientists collect seawater samples, filter out the genetic material, and match the sequences against reference databases to identify which species were recently present. Because eDNA in water degrades relatively quickly, detections generally indicate recent occupancy of an area.
Scope of the study
In a study published in PLOS Biology, a team from the University of Montpellier and the Centre National de la Recherche Scientifique (CNRS) analyzed more than 900 seawater samples taken at a variety of depths and locations—from polar seas to tropical waters. Their broad geographic and depth coverage allowed a more complete assessment of marine species distributions than many traditional surveys.
Key findings
The researchers report that the geographic ranges of over 93% of detected species had been previously underestimated: many animals occupy larger territories than recorded in existing range maps. The results also revealed surprising environmental tolerances. For example, DNA from the crocodile icefish—long thought to be confined to frigid Antarctic waters—was detected as far north as Patagonia, in waters roughly 18°F (about 10°C) warmer than typical Antarctic conditions.
Why this matters
Accurate range data are a prerequisite for assessing species’ conservation status, understanding ecological interactions, and designing effective marine protected areas. By expanding known distributions, eDNA surveys tighten the net around our knowledge of ocean life and help prioritize monitoring and conservation efforts where they are most needed.
“eDNA offers a rapid, sensitive tool to reveal hidden or unexpected patterns of marine biodiversity that conventional methods can miss.”
While powerful, eDNA is complementary to traditional methods: it identifies presence but not always abundance or life stage, so integrating eDNA with other observations gives the clearest picture of ocean ecosystems.