March 20, 2014
Understanding Leatherback Sea Turtle Habits For Conservation Efforts
Brett Smith for redOrbit.com - Your Universe Online
With the threat of climate change looming over marine conservation efforts, leatherback sea turtles have been of particular concern because they are considered an endangered species in all the world's oceans.
A new study from a team of New England-based researchers, published in the journal PLOS ONE, has added a wealth of knowledge to the understanding of leatherback sea turtle behavior – informing conservation strategies in the process.
Considered the largest turtles in the world, leatherbacks can weigh up to 2000 pounds and measure up to 7 feet long. They are warm-bodied, strong divers that have been known to go 3,000 feet below the surface. Leatherbacks also have the widest distribution of all reptiles, traveling thousands of miles between serving and mating grounds. Unlike other sea turtles, leatherbacks specifically eat soft-bodied gelatinous zooplankton such as jellyfish and salps. Their quest for these far-flung "jellies" and the turtles’ distinctive thermoregulatory ability both play a role in their extensive range.
Previous satellite tagging research on leatherbacks has centered on adult females and their tropical nesting beaches, leaving a significant knowledge gap regarding males and subadults, the researchers said. However, satellite tracking in places where leatherbacks look for food means the scientists get a much bigger picture of the leatherback's habits and dispersal patterns in the open ocean.
"Coastal ecosystems are under intense pressure worldwide, with some of the highest predicted cumulative impact in the North American eastern seaboard and the eastern Caribbean,” the study team wrote. “Parts of those regions constitute high-use habitat for leatherbacks in our study, putting turtles at heightened risk from both land- and ocean-based human activity."
The new study concluded that distinct regions, seafloor topography and sea surface temperature are the biggest factors in determining the leatherbacks' hunting patterns. The tagged leatherbacks showed a strong affinity for the Northeast US shelf during the summer and fall when full-sized jellyfish are present.
In collaboration with commercial fishermen, spotter pilots and the Massachusetts sea turtle disentanglement network, the team was able to tag 20 leatherback sea turtles off the coast of Massachusetts from 2007 to 2009.
"We started the satellite tagging work in 1994, but had little understanding of their daily lives until recently because we first wanted to develop ways to directly attach the tag without encumbering the turtle,” said study author Molly Lutcavage, a marine biologist from the Large Pelagics Research Center at the University of Massachusetts.
"Once that was accomplished, we could collect accurate track locations via GPS along with dive data, and determine the leatherbacks' residence time, high-use habitat and behavior on the Northeast US shelf and beyond," she added.
The scientists also reviewed ecological features in their study, including depth data, or bathymetry, plus remotely-sensed temperature and ocean productivity information to recognize leatherback habitat preferences.
"Our study provides new insights about how male and immature turtles behave, how they use their habitats and how that differs from adult females,” said study author Kara Dodge, who conducted the research as a part of her doctoral research. “Resource managers for protected marine species have lacked this key understanding, especially in coastal regions of the US and Caribbean where leatherbacks and intense human activity coincide."