How Researchers Are Tracking the Elusive Amazon Manatee

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AAs South Florida’s manatee populations face threats from the brunt of human impacts, from motorboat collisions to entanglements with fishing gear, it is imperative to understand how they might survive coexistence with humans. New research explores how one of their sister species, the Amazonian manatee (Trichechus inunguis), responds to increased human pressures in the Amazon basin. The study, published today in PLOS Onereveals the sensitivity of Amazonian manatees to human proximity.

In the first study to detect Amazonian manatees using environmental DNA (eDNA), a team of researchers from universities in Texas and Brazil mapped their distribution along the Amazon River and its tributaries. Since Amazonian manatees are usually only spotted when they surface to breathe, monitoring their presence is a challenge. But DNA is known to persist in running water systems for up to 43 hours, so the discovery of eDNA from a particular species is strong evidence of its recent presence in the region.

Read more: “We can write a different ending for critically endangered species”

River water was sampled along a gradient from highly disturbed urban areas to protected ecological reserves. Amazonian manatee DNA has been found in water at eight sites. Six of them were in a less disturbed area and two were closer to human populations. “Detection of Amazonian manatee DNA was more than three times higher in the western Amazon (Tefé and Mamirauá Sustainable Development Reserve) where human activity is low,” write the authors of the study.

The areas where most manatees were detected included both rural and protected conditions. It remains to be determined whether they were absent from other areas heavily frequented by shipping traffic and urban development, or whether they simply occurred in lower densities, as eDNA detectability is known to be linked to animal density. The study authors highlighted potential sources of error, such as the influence of water temperature, acidity and river flow, on eDNA detection.

Nevertheless, they conclude that “eDNA appears to have good potential to improve the accuracy of animal surveys that form the basis of biodiversity conservation.” Compared to their Florida cousins, information on Amazonian manatees is scarce, despite their vulnerable and declining status.

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Main image: Diego Grandi / Shutterstock

• Devin Reese

  Published on February 4, 2026

  Devin Reese is the editor-in-chief of Natural history and a science writer based in Alexandria, Virginia.