Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nesting Gulf Loggerheads Face Offshore Risks

16.07.2013
Long-Range Nesting Patterns Reveal New Habitats and Risks

Threatened loggerhead sea turtles in the northern Gulf of Mexico can travel distances up to several hundred miles and visit offshore habitats between nesting events in a single season, taking them through waters impacted by oil and fishing industries.

Evidence from a U.S. Geological Survey study challenges the widely-held view that sea turtles remain near one beach throughout the nesting season and suggests the threatened species may require broader habitat protection to recover. The findings also cast new uncertainties on current estimates of the size of the species’ Gulf of Mexico subpopulation.

“This is the first study to locate and quantify in-water habitat use by female loggerheads in the Northern Gulf of Mexico subpopulation during their reproductive periods,” said lead author Kristen Hart, a USGS research ecologist. “Our tracking results show they depend on a much broader range of habitat during this critical part of their lives than was previously thought to be required.”

The study reveals detailed loggerhead movements during “inter-nesting” periods, showing patterns that vary for individual turtles. Generally, this period begins when a female returns from open seas around May and lasts roughly until September. Up until now, efforts to protect the species generally centered on beaches with high nesting activity under the assumption that once turtles had nested on those beaches, they either remained in their immediate vicinity or migrated back out to sea.

“The satellite data and our observations on the ground tell the same story: loggerheads in this subpopulation nest at multiple beaches, sometimes hundreds of miles apart,” said Hart. “Some of the females we captured and tagged on beaches in Alabama traveled over 250 miles to nest in Florida, where we recaptured them. Likewise, we also captured some females in Alabama that had previously been tagged at the Florida site in earlier breeding years.”

Researchers used the same statistical technique for analyzing their movements that enabled them to pinpoint loggerhead feeding hotspots at sea last year and, more recently, locate Kemp’s ridley feeding grounds in the Northern Gulf by differentiating between behavioral modes. They analyzed where 39 adult female sea turtles went after they nested on beaches in Alabama and Florida between 2010 and 2012 to learn where they spent time in the water during the breeding season before migrating back to sea.

“We were surprised to find a lot of variation in their behavior,” said co-author and USGS biologist Meg Lamont. “On average, the tagged turtles visited areas about 33 kilometers (20 miles) from shore and moved about 28 kilometers (17 miles) to nest at another beach. Several of them journeyed more than 200 kilometers (124) miles to nest at additional beaches, while others simply cruised back out to sea after the first nest.”

The results of the study explain a mystery that had puzzled Lamont, who has 16 years of data from the St. Joseph Peninsula in Florida showing that few of the nesting loggerheads they tagged returned to nest again on the Peninsula. “We didn’t know whether they were dying or simply nesting elsewhere,” explained Lamont, “Now we know they aren’t as faithful to one nesting site as was once thought.”

One of the turtles that Lamont tagged in 2002 appeared at Hart’s site in Alabama, nearly a decade later. In fact, the researchers saw several turtles nesting both in Alabama and the St. Joseph Peninsula (roughly 250 miles apart) within a period of just two weeks.

“These data show it is not sufficient to just protect habitat around high density nesting beaches – such as the St. Joseph Peninsula – because many turtles that nest on the Peninsula use the entire region from the eastern Florida Panhandle to Louisiana,” said Lamont.

There could also be fewer female loggerheads nesting in the northern Gulf of Mexico than current estimates suggest because they are calculated using nest numbers. “Our research shows that the same turtle could easily deposit eggs in Alabama and Florida if nests are separated by about 2 weeks,” said Hart. “Population numbers based on nest counts may therefore be biased upwards if nests at the two sites were assumed to have come from two different females.”

The study also noted that the areas the loggerheads used during the inter-nesting period overlapped with human uses, such as shrimp trawling and oil and gas platforms. A map showing sea turtle habitat use in relation to these activities can be found in the article, “Movements and Habitat-Use of Loggerhead Sea Turtles in the Northern Gulf of Mexico during the Reproductive Period,” which was published July 3 in the journal PLOS One.

“We are working towards defining areas where sea turtles concentrate their activities at sea, effectively building a map of in-water turtle hotspots,” said Hart. “The more we know about their habitat use, the more questions are raised about their behavior and ability to adapt. We hope to build a better understanding of how frequently turtles return to these same locations, and whether or not they move to new habitats when those locations are impacted. This type of information would be extremely valuable for developing management strategies to help in population recovery.”

Hannah Hamilton | EurekAlert!
Further information:
http://www.usgs.gov

More articles from Studies and Analyses:

nachricht Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>