Clicking in shallow rivers : short-range echolocation of Irrawaddy and Ganges River dolphins in a shallow, acoustically complex habitat
Jensen, Frants H.
Mansur, Rubaiyat M.
Smith, Brian D.
Janik, Vincent M.
Madsen, Peter T.
MetadataShow full item record
Toothed whales (Cetacea, odontoceti) use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica) and Irrawaddy dolphins (Orcaella brevirostris) within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB) re 1 µPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191) re 1 µPapp. These source levels are 1–2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehead may help achieve a higher directionality than expected using clicks nearly an octave lower than similar sized odontocetes.
© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS ONE 8 (2013): e59284, doi:10.1371/journal.pone.0059284.
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Lai, Zhigang; Ma, Ronghua; Gao, Guangyin; Chen, Changsheng; Beardsley, Robert C. (John Wiley & Sons, 2015-08-21)Impacts of the multichannel river network on plume dynamics in the Pearl River estuary were examined using a high-resolution 3-D circulation model. The results showed that during the dry season the plume was a distinct ...
Nowacki, Daniel J.; Ogston, Andrea S.; Nittrouer, Charles A.; Fricke, Aaron T.; Van, Pham Dang Tri (John Wiley & Sons, 2015-09-23)A better understanding of flow and sediment dynamics in the lowermost portions of large-tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and ...
Tracing river chemistry in space and time : dissolved inorganic constituents of the Fraser River, Canada Voss, Britta M.; Peucker-Ehrenbrink, Bernhard; Eglinton, Timothy I.; Fiske, Gregory J.; Wang, Zhaohui Aleck; Hoering, Katherine A.; Montlucon, Daniel B.; LeCroy, Chase; Pal, Sharmila; Marsh, Steven; Gillies, Sharon L.; Janmaat, Alida; Bennett, Michelle; Downey, Bryce; Fanslau, Jenna; Fraser, Helena; Macklam-Harron, Garrett; Martinec, Michelle; Wiebe, Brayden (2013-07-19)The Fraser River basin in southwestern Canada bears unique geologic and climatic features which make it an ideal setting for investigating the origins, transformations and delivery to the coast of dissolved riverine loads ...