The Influence of Oceanographic and Biological Processes on the Distribution of Cetaceans on the West Florida Shelf

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Previous studies of cetacean distributions have been greatly limited by spatial and temporal aliasing in collection of data sets, which have hindered their ability to explain variability based on physical and biological data. This partnership brings together experts in bioacoustics, ocean acoustics, physical oceanography, remote sensing, and GIS analysis to overcome this limitation. The PIs will collect a synoptic data set over appropriate spatial scales on cetacean distributions and physical and biological processes on the West Florida Shelf. This data set will provide an unprecedented ability to resolve questions about the influences of physical, biological, and anthropogenic noise on the distribution of cetaceans. Cetaceans make a wide variety of vocalizations. Species observed in deep waters of the Gulf of Mexico typically produce vocalizations ranging from 5 to 40 kHz. A newly developed acoustic recorder, the Digital SpectroGram recorder (DSG), will be used to overcome the data storage and battery problems associated with other recorder designs. A sparse array of 73 DSG recorders will be deployed over a 48,750 km2 area, to determine the relative spatial and temporal distribution of cetaceans on the West Florida Shelf. Towed array recordings will also be used to determine source levels of cetacean vocalizations to model the effective sampling area of each recorder. A library of sounds produced by the cetaceans on the West Florida Shelf will also be compiled from existing recordings and new array recordings to analyze species-specific distributions. How noise levels affect cetacean distribution and activity is an important element of cetacean stock management. The hydrophone array will be used to quantify ambient noise levels and to model sound propagation on the West Florida Shelf. Concurrent physical and biological oceanographic data will be collected; in-situ, with satellite remote sensing, and interpreted with the aid of numerical circulation models. With this multilayered data set, we will be able to investigate the spatial and temporal patterns of oceanographic variables on the West Florida Shelf in a multidisciplinary manner. Broader ImpactsThese data will form a baseline that can be used to understand how marine mammals react to noise sources, such as seismic surveys. This work will also involve the education of a Ph.D.-level graduate student.