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Researchers find that otter poop can tell important information about the ecosystem

<i>WJZ via CNN Newsource</i><br/>A new study from the Smithsonian Environmental Research Center in Edgewater

By CNN Newsource

Published August 21, 2025 7:25 am

By Caroline Foreback

EDGEWATER, Maryland (WJZ) — Otters may look adorable, but scientists say their poop is a goldmine of information.

A new study from the Smithsonian Environmental Research Center in Edgewater, Maryland, found that otter poop, or “scat,” serves as a natural report card for the ecosystem.

What does otter poop tell us?

A team of scientists at the Smithsonian Environmental Research Center spent the past few years collecting and studying otter poop from these latrines along the Rhode River.

Their study, published last week, found otter scat contains important clues about what’s going on in our waterways.

“As an apex predator and a disease sentinel, river otters can serve as a sort of an indicator of the health of the ecosystem and if things are or are not going well,” said Calli Wise, the lead author of the study.

By testing the droppings, researchers found that otters are eating fish and a lot of crustaceans, along with smaller mammals and birds, most importantly parasites.

“The fact that river otters eat so many parasites is actually really important for the health of the ecosystem, and the people that rely on this ecosystem for a living.”

Parasites can be a warning sign for water health

Wise says parasites help balance the food chain, and because otters live both on land and in water, the parasites in their prey can be an early warning system for environmental changes.

“Seeing if that changes over time can be a flag, a signal to people when things are going well or poorly in the water,” Wise said.

Otters can even warn of potential risks to humans.

“Those would be things that we’d look at as indicators of poor water quality or sewage or other things in the water column.”

The team hopes their findings will aid restoration efforts in the future.

“It’s been really fun to see otters popping up in more urban spaces and see people get excited about conservation related to this species.”

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Kara Nelson
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