Loggerhead turtles affixed with satellite tags have given researchers new data on their behavior when a hurricane passes. This data may also prove useful in weather modeling and hurricane research. Falmouth-based researchers affiliated with NOAA recently published their work on the subject in Movement Ecology.
In 2011, a total of 26 loggerhead turtles were satellite-tagged on their shells and tracked in the Atlantic off Delaware, Maryland, and New Jersey. The tags relayed the turtle’s locations and dive behaviors. The tags also recorded surface and below-surface temperatures over the course of 13 months.
On August 28 of that year, Hurricane Irene swept through the region. Of the 26 turtles, 18 were in the path of the hurricane. “‘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 might be influenced by these dramatic environmental changes,” Leah Crowe, a contract field biologist at the NOAA Northeast Fisheries Science Center’s laboratory in Woods Hole, and lead author of the study, said via a release. “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.’”
The turtles evidenced several different behaviors. “Most of the turtles moved northward during the hurricane,” a release states, “aligning themselves with the surface currents — perhaps to conserve energy. Researchers observed longer dive durations after the hurricane for turtles that stayed in their pre-storm foraging areas. Some dives lasted an hour or more, compared with less than 30 minutes for a typical dive before the storm. The turtles that left their foraging areas after the hurricane passed moved south earlier than would be expected, based on their normal seasonal movements. This change was also more than a month earlier than the typical seasonal cooling in the water column, which is also when the foraging season for loggerhead turtles ends in the Mid-Atlantic Bight.”
Other studies have looked at how major weather systems affect certain marine species, but the release states there are few studies of sea turtle interactions with large storms.
“In this study, turtle behavior did not return to pre-storm behavior within two weeks after the storm,” the release states. “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. Changes in sea turtle movements and behavior can affect abundance estimates and management decisions,” Crowe said in the release. “This study reminds us that turtles live in a dynamic environment, and we cannot assume their behavior will be consistent throughout space and time.’”
Data from the turtle’s tags were in accord with data from other weather-monitoring devices like data buoys and glider drones. The study suggests that if enough turtles were deployed with tags, their data coverage could be more extensive than the coverage from pre-existing devices.
The overall study was done by researchers at the Northeast Fisheries Science Center and other researchers in close proximity at Coonamessett Farm Foundation in East Falmouth.
This team has tagged 200 loggerhead turtles in the Mid-Atlantic Bight since 2009.
