ESR 33:83-93 (2017)  -  DOI: https://doi.org/10.3354/esr00794

Impact of the Deepwater Horizon oil spill on loggerhead turtle Caretta caretta nest densities in northwest Florida

Ann Marie Lauritsen1,*, Philip M. Dixon2, Dave Cacela3, Beth Brost4, Robert Hardy4, Sandra L. MacPherson1, Anne Meylan4, Bryan P. Wallace3,5, Blair Witherington6

1US Fish and Wildlife Service, Jacksonville, Florida 32256, USA
2Iowa State University, Ames, Iowa 50011, USA
3Abt Associates Inc., Boulder, Colorado 80302, USA
4Florida Fish and Wildlife Conservation Commission, St. Petersburg, Florida 33701, USA
5Duke University Marine Lab, Beaufort, North Carolina 28516, USA
6Disney’s Animals, Science and Environment, Lake Buena Vista, Florida 32830, USA
*Corresponding author:

ABSTRACT: The 2010 Deepwater Horizon (DWH) oil spill and associated response activities overlapped with habitats for multiple life stages of federally protected sea turtles in the northern Gulf of Mexico. Although most assessment efforts focused on documenting the presence, abundance, and exposure of sea turtles to DWH oil in marine habitats, oil also washed ashore on sand beaches used by nesting turtles, specifically in NW Florida and Alabama, USA. In addition, extensive and highly mechanized beach cleanup efforts were conducted in NW Florida as well as Alabama, Louisiana, and Mississippi. Thus, the DWH oil spill negatively affected sea turtle nesting directly (e.g. adverse effects of oil exposure) and indirectly (e.g. beach cleanup activities deterring nesting) in several ways. In this study, we used a before-after, control-impact statistical modeling approach to examine long-term (1997-2012) historical records of loggerhead turtle (Caretta caretta) nest densities in 2 segments of the Florida Gulf coastline, one that was heavily affected by the oil spill (NW Florida) and one that was relatively unaffected (SW Florida). Loggerhead nest densities on NW Florida beaches in 2010 were reduced by 43.7% (95% confidence interval: 10-65%) relative to expected nesting rates in the absence of DWH oil and cleanup efforts. When we applied this reduction to all nesting habitat in NW Florida, this equated to a loss of approximately 251 unrealized nests from the 2010 nesting season—a loss we attribute to direct (e.g. mortality) and indirect (e.g. deterrence of nesting) effects related to the DWH incident.


KEY WORDS: Caretta caretta · Deepwater Horizon oil spill · Natural Resource Damage Assessment · Oil spill injury · Sea turtle nesting


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Cite this article as: Lauritsen AM, Dixon PM, Cacela D, Brost B and others (2017) Impact of the Deepwater Horizon oil spill on loggerhead turtle Caretta caretta nest densities in northwest Florida. Endang Species Res 33:83-93. https://doi.org/10.3354/esr00794

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