POPs Detected In Loggerhead Sea Turtles

            Loggerhead sea turtles, (Caretta caretta) are large benthic consumers that have recently become of particular interest to scientists. Although loggerhead sea turtles have been on the U.S. Endangered Species Act for over thirty years, little information is known about the male species due to the rarity of it being encountered by humans. Unknown information includes migration patterns, exposure and risks of persistent organic pollutants (POPs), and prey choice. The primary exposure route of bioaccumulation contaminants in loggerhead turtles is through trophic transfer. Previous POPs detected in juvenile and female loggerhead turtles include: organchlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). In related studies, marine predators have also had elevated levels of toxaphenes and hexabromocyclododecanes (HBCDs). These contaminants have been known to cause cancer and negatively impact growth, development, and reproduction.

            The first study to test POPs in male loggerhead turtles’ blood plasma based on migration patterns was conducted by Ragland et al. in April of 2006 and 2007. The article is titled “Persistent organic pollutants in blood plasma of satellite-tracked adult male loggerhead sea turtles (Caretta caretta).” The 29 sea turtles were captured near Port Canaveral, Florida and blood samples were drawn from the back of the neck and analyzed using gas chromatography-mass spectrometry. Also, satellite transmitters were placed on the back of the shells of the turtles to track migration patterns for sixty days each sample year. The satellite tracking devices indicated that nine individuals were residents and remained near the capture site, whereas ten transients migrated northward near Pamlico Sound, North Carolina to as far as Cape May, New Jersey. Results of the blood plasma analysis indicated that OCPs and PBDEs were greater in transients that residents. The possible causes for this could be correlated to turtle size, increased industrialization, land use, higher human population, and a bigger watershed in the north compared to a smaller watershed in Florida. Lastly, the study found that total PCB levels were also slightly greater in transients than residents indicating different diets and foraging patterns.        

            Nicholas Bakalar, from The New York Times reported on these findings in his article titled “Migrating Sea Turtles Pick Up More Pollution.” Bakalar emphasizes that 67 different chemicals most likely originating from pesticides were found in the blood of the loggerhead sea turtles. Bakalar states, “It is possible that the fish and invertebrates that turtles feed on in northern waters are more polluted.” A possible cause for this is sea turtles that migrate far distances usually consume more food and are on average larger in size than residents. However, it is unclear to scientists how to define “good health” in loggerhead sea turtles, since they all seemed to be reproductively active based on testicular biopsies.            

My main issue with the original research article is 29 sea turtles were tracked yet only 19 were analyzed for POPs. Ragland et al. fails to mention why the other 10 individuals weren’t included in this study, was it due to lack of POP’s or migration patterns? Another issue I had with this research is Ragland et al. never mentioned whether or not they recaptured these 29 individuals to remove the satellite tracking devices from their shells. This alarms me because this could impact migration, reproduction, foraging, and their ability to prosper since they are already an endangered species.  However, I did like the fact that future studies were suggested to elaborate on this research since this was the first study of its kind.

Overall, I think Nicholas Bakalar from The New York Times accurately reported on the findings of the original research article by Ragland et al. The article is merely a summary of the findings; Bakalar does not add any opinions or ideas of his own to this topic. However, I think he does a good job of getting the message across that man-made pollution is putting loggerhead sea turtles at risk. I would give The New York Times article a 9/10 because I see no problems with the accuracy of this brief article, but I would have liked an outside perspective on the subject matter.

Original Research Article:

Ragland, J. M., Arendt, M. D., Kucklick, J. R. and Keller, J. M. (2011), Persistent organic pollutants in blood plasma of satellite-tracked adult male loggerhead sea turtles (Caretta caretta). Environmental Toxicology and Chemistry, 30: 1549–1556.

http://onlinelibrary.wiley.com/doi/10.1002/etc.540/full

Media Article:

Bakalar, Nicholas. (2011), Migrating Sea Turtles Pick Up More Pollution. The New York Times.
http://www.nytimes.com/2011/04/26/science/26obturtles.html