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This Is How Pollution Changes Hawaii’s Sea Turtles

<p><a class="checked-link" href="https://www.flickr.com/photos/jurvetson/" style="text-decoration: none;">Steve Jurvetson</a>/Flickr/CC BY SA 2.0</p>

Humans living along Hawaii's coast are negatively affecting nearby green sea turtles, a new report has found.

Agricultural and urban runoff is linked to more tumorous growths on the sea turtles, according to marine biologists at the National Oceanic and Atmospheric Administration, Duke University and the University of Hawaii.

WARNING: Some people may find the image below unsettling.

"We're drawing direct lines from human nutrient inputs to the reef ecosystem, and how it affects wildlife," says Van Houtan, a Duke biologist and a scientist with NOAA's Turtle Research Program, in a statement.

Researchers tracked down where green turtles had high rates of fibropapillomatosis, a disease that causes large white tumors to sprout up around turtles' eyes, flippers and armpits.

A young sea turtle with severe fibropapillomatosis. (Photo: Chris Stankis)

Examining the turtles' tumors revealed unusually high amounts of a molecule called arginine - a trait the sick reptiles shared with their primary food source, algae. One species of algae, Hypnea musciformis, is packed with arginine; this invasive species both outcompetes local algae and is less nutritious, so sea turtles need to eat twice as much Hypnea to get the same calories native algae would offer.

Turtles who chow down on Hypnea, the scientist believe, suffer from the highest instance of tumors. "If this disease is a car, arginine its fuel," Van Houtan says. These reptiles may be ingesting anywhere from 5 to 14 times more arginine near polluted reefs, the scientists report in the journal PeerJ.

When sewage leaches into the sea - specifically, the nitrogen within the pollution - it kindles algal growth, triggering a "nutrient cascade" that ends up as turtle tumors. That's bad news for the turtles, who are also threatened by habitat loss and fishing hooks (Hawaii's green turtles are listed as threatened under the Endangered Species Act).

If it goes untreated, fibropapillomatosis is deadly. But there's a ray of hope for turtles who receive medical attention, as one Florida sea turtle named Yertle demonstrated back in May. And despite the emergence of this disease, which is becoming more common in some Hawaiian areas, the green turtle population is slowly recovering after years of overharvesting.