Detection of dolphin burst-pulses off Cape Hatteras, North Carolina, correlated to oceanographic features

Le résumé fourni par la source

To assess the ecological impact of extracting energy from the Gulf Stream, the University of North Carolina Coastal Studies Institute has deployed a mooring on the continental slope off Cape Hatteras at a depth of 230 m, equipped with an Acoustic Doppler Current Profiler, CTD, and a hydrophone. Analyzing 16 months of data, we automatically detected dolphin “quacks” or “barks”, using two detectors. First, we used a pitch detector to automatically detect such signals over a specified range of pitch values. Next, we used a matched filter approach. All detections were reviewed manually to eliminate false alarms. For these signals, we found a strong correlation with temperature and salinity at the bottom; the vocalizations were detected when the water was relatively cooler and fresher. As the Gulf Stream meanders seaward of the mooring site, the temperature and salinity there both decrease. Since this cooler water is higher in nutrients, one explanation for the correlation is that the marine mammals are attracted to this more productive water. Alternatively, the meandering Gulf Stream may influence either (a) the acoustic propagation around the mooring and/or (b) the acoustic noise around the mooring. Evidence for each alternative will be presented.

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