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Loggerhead Turtles Report On Hurricane

Turtle swimming near the top of the sea
NOAA

When Hurricane Irene passed along the east coast of the United States in August 2011, the National Oceanic and Atmospheric Administration (NOAA) got reports from a most unusual team of weather reporters: 18 loggerhead turtles.

Perfect Storm

So how did the hard-shelled reptiles accomplish this impressive feat?

Scientists had tagged them earlier with satellite transmitters that not only record the turtles’ behaviors, but also the temperatures of the water in which they live—the Mid-Atlantic Bight, an area that stretches along the coast of North Carolina up through Massachusetts.

“Hurricanes are some of the most intense weather events loggerheads in the mid-Atlantic experience, and we thought it was worth investigating how turtles in our dataset may be influenced by these dramatic environmental changes,” said Leah Crowe, a contract field biologist at the NOAA Northeast Fisheries Science Center’s laboratory in Woods Hole, Massachusetts, and lead author of the study published recently in Movement Ecology. “It was a perfect-storm situation in terms of location, timing, and oceanographic conditions. We found that the turtles responded to the changes in their habitat in different ways.”

Should I Stay or Should I Go?

In their observations, the researchers noticed that the turtles split into two groups. The majority of them rode surface currents northward before the storm in what may have been an effort to save energy and get out of the path of the hurricane. The other turtles stayed put in their foraging area.

The turtles that were stationary changed their diving behavior after the storm, submerging themselves for over an hour, almost double the time they usually stay under. And the turtles who left wound up migrating south a full month earlier than usual. While the reason for these reactions is unknown, the researchers found the information valuable and were happy to add it to the ten years of data they’ve already collected from the project.

“The long-term cumulative effects of a changing climate and the increase in intensity of hurricanes and other storms is something that needs to be looked at,” said Crowe. “Changes in sea turtle movements and behavior can affect abundance estimates and management decisions. This study reminds us that turtles live in a dynamic environment, and we cannot assume their behavior will be consistent throughout space and time.”

Temperature Taking

In addition to monitoring the turtles themselves, the NOAA study also used the sensing chips on the turtles’ shells to confirm water-temperature data. Because the animals dive through the water column and the different temperature striations it contains, the data they provide is extremely helpful.

The data matched that which was returned by water buoys in the area, confirming that the turtles are indeed a useful resource for monitoring sea conditions. The researchers say that the data the turtles provide could be used to improve weather modeling and hurricane predictions.

“Loggerheads experience environmental changes in the entire water column from the surface to the bottom, including during extreme weather events,” said Crowe. “This study was an opportunistic look at turtle behavior during a hurricane. Their behavior makes loggerheads good observers of oceanographic conditions where they forage.”