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ESR 33:181-192 (2017)  -  DOI:

Using salinity to identify common bottlenose dolphin habitat in Barataria Bay, Louisiana, USA

Fawn E. Hornsby1,*, Trent L. McDonald1, Brian C. Balmer2, Todd R. Speakman2, Keith D. Mullin3, Patricia E. Rosel4, Randall S. Wells5, Andrew C. Telander1, Peter W. Marcy1, Kristen C. Klaphake1,**, Lori H. Schwacke2

1Western EcoSystems Technology, Inc., Laramie, WY 82072, USA
2National Centers for Coastal Ocean Science, National Oceanic and Atmospheric Administration, Hollings Marine Laboratory, Charleston, SC 29412, USA
3Southeast Fisheries Science Center, National Marine Fisheries Service, NOAA, Pascagoula, MS 39568, USA
4Southeast Fisheries Science Center, National Marine Fisheries Service, NOAA, Lafayette, LA 70506, USA
5Sarasota Dolphin Research Program, Chicago Zoological Society, c/o Mote Marine Laboratory, Sarasota, FL 34236, USA
*Corresponding author: **Cartographer

ABSTRACT: Following the Deepwater Horizon (DWH) oil spill, numerous studies were conducted to determine impacts on common bottlenose dolphins Tursiops truncatus. Common bottlenose dolphins are found in estuarine environments of the northern Gulf of Mexico which vary in salinity, depending on location (e.g. distance to freshwater source), season, and ocean tides. Although common bottlenose dolphins can be found in low-salinity waters (<15 ppt), they cannot tolerate very low salinity for long periods of time. We matched dolphin telemetry data in Barataria Bay, Louisiana (USA), with contemporaneous estimates of salinity to establish a salinity threshold and identify preferred dolphin habitat. Dolphins frequently used areas where salinity was higher than ~11 ppt, sometimes used areas for short periods of time with predicted salinity of ~8 ppt, and avoided waters with salinities below ~5 ppt. While not a hard boundary, the ~8 ppt threshold can be used to delineate reasonable polygons of preferred dolphin habitat. We temporally averaged the location of the ~8 ppt isohaline from 2005 through 2012 to establish areas of preferred dolphin habitat. In Barataria Bay, the polygon of dolphin habitat encompasses 1167 km2, and extends from the bay’s barrier islands to approximately half-way through marshes in northern parts of the bay. This polygon of suitable common bottlenose dolphin habitat was then ultimately used to quantify cetacean injury due to DWH oil.

KEY WORDS: Tursiops truncatus · Habitat · Deepwater Horizon · Barataria Bay · Telemetry · Salinity · Photo-ID

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Cite this article as: Hornsby FE, McDonald TL, Balmer BC, Speakman TR and others (2017) Using salinity to identify common bottlenose dolphin habitat in Barataria Bay, Louisiana, USA. Endang Species Res 33:181-192.

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