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Study Points To Mixed Results For Turtles 10 Years After Oil Spill

The female turtle is much bigger than the male. Both have dark shells and their heads pulled inside the shell.
Sehvilla Mann

Josh Otten sits in a kayak in the Kalamazoo River west of Battle Creek. He’s pulled up to the bank, holding a palm-sized, wriggling black-and-yellow-striped turtle. Otten turns it over, showing the dark lines and brown spots on its plastron (the underside of the shell). This is a northern map turtle, the most abundant species in the river.


“The reason why they get their common name is they have all those little lines on their shells, so it kind of looks like a topographic map,” Otten explains.

Ten years after an oil spill coated miles of the Kalamazoo River, researchers are checking up on the turtles that live there. While many turtles that got oiled appear to be thriving, individuals that were young during the spill might not have done so well. Otten, a biologist who specializes in turtles, has been gathering data for the study for three years.

He’s heading out for a day of fieldwork, which means he’ll spend a lot of time sidling up to basking turtles, hoping they jump into his net and not the other way. He caught the palm-sized map turtle as soon as he hit the water. He weighs it, measures it, then files a notch in its shell. Annoying but not painful for the turtle, he explained, before slipping it back in the water.

“That way I can know if I recapture this one,” he added.

Following up

The study returned Otten to a river he got to know well in 2010. That’s when Enbridge Energy’s Line 6B pipeline broke near Marshall, sending upward of a million gallons of crude oil into the river. Otten ended up on the scene days later because he worked for a company that Enbridge hired for cleanup. Now Otten’s working on his PhD at the University of Toledo, the school that’s heading up the turtle study.

“He’s probably done the biggest map turtle population study that’s ever been done,” said Lisa Williams, an East Lansing-based contaminant specialist with the U.S. Fish and Wildlife Service who helped supervise the oil cleanup in 2010.

A close-up view of a small turtle with brown spots and dark lines on the underside of its shell. The turtle has its head, legs and tail out of the shell.
Credit Sehvilla Mann / WMUK
A small northern map turtle, with markings on its plastron.

Williams said turtles had it bad during the spill. Especially northern map turtles. They’re always coming up to breathe and to bask.

“We believe nearly every turtle within miles of the river got oiled,” she said.

A multimillion-dollar settlement with Enbridge focused on restoration, not research. But Williams said the settlement made an exception of sorts for turtles because they suffered so much in the spill.  The settlement funded the turtle study because it’s intended to help protect turtle nests. Some of the research has focused on nesting habits. Williams says it’s shown that river turtles will travel to find a good spot for their eggs.

“They’re not like sea turtles, they’re not huge! You can hold one in the palm of your hand and yet they go miles to nest, it’s amazing,” she said.

But in tracking turtles’ numbers, their size and weight, the study will also probe for effects of the oil spill.

Some turtles got microchipped during the cleanup. That means Josh Otten can scan for them as he paddles the river. On his run last week, the tracker beeped and he spotted the turtle before it headed for some woody debris.

“I’ll go ahead and collect a data point for this particular turtle,” he noted.

“A disturbing indicator”

Otten said he’s recaptured many microchipped turtles. It’s a good sign. It means plenty of turtles that survived the oil spill are still going. But after the spill, cleaners noticed they weren’t finding many young turtles. Now, Otten says he doesn’t catch as many eight-to-12 year olds as he’d expect. Something caused the population to dip around the time of the spill.

“It could have been the spill,” Williams said. “It could have been the response to the spill, the fact that river was suddenly full of boats and equipment and sediments are being disturbed, the banks are being cleaned up.”

The oil might have trapped some small turtles as it weathered and thickened in the river. And Williams said cleaners might have removed some turtles as they took oil out of the river.

“If there were turtles that were kind of stuck in that oil and they were small, they would have been vacuumed up with the oil,” she said.

The river also flooded in July 2010. That could have affected young turtles. Williams says at this stage, it’s hard to pinpoint the cause.

Otten is wearing a ball cap, sunglasses and a pink tie dye shirt. He's holding a turtle in each hand. The river is behind him.
Credit Sehvilla Mann / WMUK
Josh Otten by the Kalamazoo River.

“But it’s a disturbing indicator that the spill could have had a pretty significant impact on the young turtles in those years,” she added.

About six hours after Otten set out to track turtles, he finished his run in Galesburg. He’s tired from spending hours in the sun. “But I caught 20!” he said. “Which is a good day for down this stretch.”

This fall Otten plans to wrap up the turtle catching. Then he’ll dig into the mound of data he’s collected in the last few years. He hopes that results in a truly detailed picture of how turtles in the river are doing.

Sehvilla Mann joined WMUK’s news team in 2014 as a reporter on the local government and education beats. She covered those topics and more in eight years of reporting for the Station, before becoming news director in 2022.
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