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Wednesday, April 11 • 4:45pm - 5:00pm
WILDLIFE MANAGEMENT: Sea Turtle Abundance, Distribution, and Habitat Selection in the Gulf of Mexico Following the Deepwater Horizon Oil Spill

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AUTHORS: Alexander Sacco*, University of Central Florida; Nathan Putman, LGL Ecological Research Associates Inc.; Lance Garrison, Southeast Fisheries Science Center National Marine Fisheries Service; Christopher Sasso, Southeast Fisheries Science Center National Marine Fisheries Service; Erin Seney, University of Central Florida; Kate Mansfield, University of Central Florida

ABSTRACT: Five species of sea turtles spend at least part of their life in the Gulf of Mexico. The 2010 Deepwater Horizon oil blowout affected marine life in the Gulf of Mexico, including all sea turtle life history stages. A major challenge during and after the oil spill was estimating the areas of highest impact on marine turtles, primarily due to the lack of data on abundance and habitat preferences in marine ecosystems. We analyzed aerial survey data collected during spring (April–May), summer (July–September), and fall (October–December) 2011, and winter (January–March) 2012 to estimate the abundance and density of four species of sea turtles (loggerhead (Caretta caretta), green (Chelonia mydas), leatherback (Dermochelys coriacea), and Kemp’s ridley (Lepidochelys kempii) sea turtles; SCL>40cm) over the continental shelf in the Gulf of Mexico. Double-observer distance sampling was used to collect turtle observations. After correcting for availability bias, as turtles spend large amounts of time below the sea surface, detection typically range from 1.1–10.5% for all seasons surveyed and turtle abundance estimates indicate significant seasonal variation. Ensemble niche models (ENM) were used to predict density probabilities for all turtles observed during the non-nesting and nesting seasons, extrapolated throughout the Gulf of Mexico region. Environmental predictors include bathymetry and daily modeled oceanographic outputs from the Hybrid Coordinate Ocean Model (HYCOM; freshwater flux, mixed-layer depth, salinity, sea-surface height, sea-surface temperature, and ocean current vectors) centered on presence-pseudoabsence turtle observations. ENM AUC were all above 0.830 and distribution exhibited species-specific and seasonal variation, delineated mainly by bathymetry, sea-surface temperature, and freshwater flux. These data will aid research on post-disaster baseline distribution variance, help assess future anthropogenic impacts, and inform ecosystem models for the Gulf of Mexico and elsewhere.

Wednesday April 11, 2018 4:45pm - 5:00pm CDT
LaSalle 1 (7th Floor)