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ESR 47:29-47 (2022)  -  DOI: https://doi.org/10.3354/esr01164

Decomposition of Kemp’s ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtle carcasses and its application to backtrack modeling of beach strandings

Redwood W. Nero1, Melissa Cook2,*, Jaymie L. Reneker3, Zhankun Wang4,5, Emma A. Schultz3, Brian A. Stacy6

1National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center, Building 1021, Stennis Space Center, Mississippi 39529, USA
2National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center, Pascagoula, Mississippi 39567, USA
3Riverside Technologies Inc., Southeast Fisheries Science Center, Pascagoula, Mississippi 39567, USA
4National Oceanic and Atmospheric Administration National Centers for Environmental Information, Stennis Space Center, Mississippi 39529, USA
5Northern Gulf Institute, Mississippi State University, Stennis Space Center, Mississippi 39529, USA
6National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Protected Resources, University of Florida, College of Veterinary Medicine (duty station), Gainesville, Florida 32611, USA
*Corresponding author:

ABSTRACT: When a sea turtle dies, it typically sinks to the bottom, begins decomposing, and floats to the surface once sufficient internal gases have accumulated to produce positive buoyancy. This process is poorly characterized and is essential to understanding where and when sea turtles found on shore may have died. We conducted decomposition studies with detailed time-temperature histories using carcasses of cold-stunned sea turtles (22 Kemp’s ridleys Lepidochelys kempii and 15 green sea turtles Chelonia mydas) at temperatures of 14-32°C and depths of 2.2-9.5 m. We found strong depth/pressure-related effects; carcasses took longer to float when incubated at greater depths than shallower depths at similar temperatures. Furthermore, carcasses incubated at colder temperatures (~15°C) took 8 times longer to float than those at 32°C at the same depth. We applied accumulated degree hours (ADH; hourly sum of ambient temperatures a carcass experienced) to characterize environmental conditions associated with different stages of decomposition and key events, including buoyancy and sinking. A formula for temperature-correction of ADH was calculated to fit a non-linear increase in decomposition at higher temperatures. These data were then used to improve an existing backtracking model by incorporating water temperature, depth (pressure), bathymetry, and postmortem condition. Heat maps of the probable mortality locations from the model agreed well with carcass and effigy drift experiments, demonstrating the overall reliability of the enhanced model. Our method can be used to estimate at-sea locations where sea turtles found washed ashore in the northern Gulf of Mexico likely died and may help inform similar efforts in other regions.


KEY WORDS: Carcass decomposition · Backtrack model · Sea turtle · Strandings · Endangered species


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Cite this article as: Nero RW, Cook M, Reneker JL, Wang Z, Schultz EA, Stacy BA (2022) Decomposition of Kemp’s ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtle carcasses and its application to backtrack modeling of beach strandings. Endang Species Res 47:29-47. https://doi.org/10.3354/esr01164

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