In early June 2011, NOAA Fisheries researchers and colleagues put satellite tags on 26 loggerhead sea turtles in the Mid-Atlantic Bight. The tagging became part of ongoing research studies of loggerhead movements and habits. The Mid-Atlantic Bight, off the U.S. East Coast, is the coastal area from Cape Hatteras, North Carolina to southern Massachusetts. A little more than 2 months later, on August 28, Cyclone Irene went through the area, putting 18 of the tagged turtles in its direct course. The researchers had the ability to track changes in the turtles’ habits accompanying the typhoon, and found that they responded in various ways.
” Hurricanes are a few of the most extreme weather occasions loggerheads in the mid-Atlantic experience, and we believed it deserved examining how turtles in our dataset might be influenced by these significant environmental modifications,” stated 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 released recently in Motion Ecology “It was a perfect storm circumstance in regards to place, timing, and oceanographic conditions. We discovered that the turtles responded to the changes in their environment in various ways.”
Satellite tags attached to a turtle’s carapace, or shell, sent the turtles’ location and dive habits. This allowed the researchers to examine the movements of 18 juvenile and adult-sized loggerhead turtles and associated oceanographic conditions as the hurricane moved through the area.
Most of the turtles moved northward during the typhoon, aligning themselves with the surface currents– maybe to conserve energy. Researchers observed longer dive periods after the typhoon for turtles that stayed in their pre-storm foraging locations.
The turtles that left their foraging locations after the cyclone passed moved south earlier than would be expected, based upon their normal seasonal movements. This modification was also more than a month previously 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.
” Loggerheads experience ecological changes in the whole water column from the surface area to the bottom, consisting of throughout severe weather condition occasions,” stated Crowe. “This study was an opportunistic take a look at turtle behavior during a cyclone. Their behavior makes loggerheads great observers of oceanographic conditions where they forage.”
The research study was carried out by scientists at the Northeast Fisheries Science Center and associates at the close-by Coonamessett Farm Foundation in East Falmouth, Massachusetts. The team has tagged more than 200 loggerheads in the Mid-Atlantic Bight because 2009.
This work has actually produced a constant time-series of information on loggerhead sea turtles. With 10 years of data, researchers can now get a deeper understanding of how turtles act and what ecological elements drive them. They can also look back at the data and ask brand-new questions, as they performed in this study.
Waters in the Mid-Atlantic Bight are extremely stratified, or layered, by temperature level in the summertime. At the surface, water is warm. A cold layer, also called a cold swimming pool, forms below this warm layer and is present from May to October. The existence of the cold swimming pool overlaps with the Atlantic cyclone season, which runs from June through November. It likewise overlaps with the presence of foraging loggerheads that remain in the area in between May and September.
Cyclone modeling is particularly tough in the Mid-Atlantic Bight since of the cold pool. In this study, it was unclear which aspect of the ecological modifications prompted behavioral modifications. Previous research studies have actually found that loggerhead habits appears to be conscious modifications in water temperature levels throughout the water column. Hurricanes trigger the water layers to mix, which creates cooler surface area temperature levels. The blending also interrupts the thermocline– the limit layer in between warm surface area waters and colder, much deeper waters.
Ocean temperature information tape-recorded by the turtles’ satellite tags are consistent with observations from weather buoys and self-governing gliders operating in the region. Depending on the number of tags are released, information from tagged turtles can cover a more comprehensive area within a season than other oceanographic data sources.
More measurements of water temperatures throughout the water column in the area could assist enhance oceanographic models. Scientists state information from the turtle tags are an underused resource that has the prospective to enhance weather models, consisting of hurricane models.
Many of the natural and human-induced impacts on sea turtle behavior, or the environments that sea turtles reside in, are still unknown.
Previous research studies show that sounds from dredge operations, seismic activity, offshore wind farm advancement, and marine recreation may likewise impact sea turtle circulation and dive behavior. Turtles may be affected straight or through environment alterations. While studies have actually taken a look at how hurricanes and typhoons impact some marine species, there are couple of examples of taking a look at sea turtle interactions with big storms.
In this research study, turtle habits did not return to pre-storm behavior within 2 weeks after the storm.
” The long-lasting cumulative impacts of an altering climate and the boost in strength of hurricanes and other storms is something that needs to be looked at. Changes in sea turtle motions and behavior can impact abundance estimates and management choices,” Crowe said.
The research study was supported by funds from the Atlantic Marine Assessment Program for Protected Types and the New England/Greater Atlantic Area’s Research Set-Aside Program.