New publication: Echolocation click source parameters of Australian snubfin dolphins (Orcaella heinsohni) - de Freitas et al.,
Dear all, We are pleased to announce the publication of the following article in the Journal of the Acoustical Society of America. de Freitas, M., Smith, J. N., Jensen, F. H., Beedholm, K., and Madsen, P. T. (2018). “Echolocation click source parameters of Australian snubfin dolphins (Orcaella heinsohni),” J. Acoust. Soc. Am., 143, 2564–2569. doi:10.1121/1.5034174 ABSTRACT: The Australian snubfin dolphin (Orcaella heinsohni) is endemic to Australian waters, yet little is known about its abundance and habitat use. To investigate the feasibility of Passive Acoustic Monitoring for snubfin dolphins, biosonar clicks were recorded in Cygnet Bay, Australia, using a four-element hydrophone array. Clicks had a mean source level of 200 ± 5 dB re 1 μPa pp, transmission directivity index of 24 dB, mean centroid frequency of 98 ± 9 kHz, and a root-mean-square bandwidth of 31 ± 3 kHz. Such properties lend themselves to passive acoustic monitoring, but are comparable to similarly-sized delphinids, thus requiring additional cues to discriminate between snubfins and sympatric species. The article can be downloaded from the JASA site: https://asa.scitation.org/doi/abs/10.1121/1.5034174 <https://asa.scitation.org/doi/abs/10.1121/1.5034174> Alternatively, feel free to contact me directly for a PDF copy: mafalda.df@gmail.com <mailto:mafalda.df@gmail.com> Best, Mafalda de Freitas
Dear all, My co-authors and I are pleased to announce the publication of a new article: Pomerleau C., Matthews C.J.D., Gobeil C., Stern G.A., Ferguson S.H., Macdonald R.W. (2018). Mercury and stable isotope cycles in baleen plates are consistent with year-round feeding in two bowhead whale (Balaena mysticetus) populations. Polar Biology. doi: 10.1007/s00300-018-2329-y ABSTRACT: Previous studies have demonstrated that the analysis of biogeochemical tracers along baleen can provide seasonal, annual, and longer term insights into whale movements, habitat use, diet, and ecosystem processes. We measured the mercury (Hg) concentration and stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope compositions along baleen plates of bowhead whales (Balaena mysticetus) harvested between 1988 and 1996 from the Bering–Chukchi–Beaufort (BCB) and the Eastern Canada–West Greenland (EC–WG) populations. These measurements were compared among individuals and between populations to assess seasonal cycling and to determine if bowhead whales forage year-round rather than fasting in winter. Individuals from the BCB population had synchronous cycles with higher Hg concentrations and lower δ¹³C values in summer and lower Hg concentrations and higher δ¹³C values in winter. EC–WG individuals also had synchronized periodic variations with peak values in isotopic ratios during summer. These results reflect an annual cycle of seasonal migration between distinct food webs in both populations. Spring and fall feeding activity was indicated in the intra-annual Hg and δ¹³C cycles along the baleen plates of all whales in our study. These shorter periods, spanning about half the annual growth, have not been previously described in the baleen of these populations, and are consistent with separate foraging areas along the migration routes. The results of this study provide further support for year-round foraging in a species previously thought to fast during winter. Future monitoring of seasonal foraging patterns in baleen would help to determine whether bowhead whales alter their foraging patterns in response to shifts in zooplankton community availability, composition, and phenology. A pdf version is available at: https://link.springer.com/article/10.1007/s00300-018-2329-y <https://link.springer.com/article/10.1007/s00300-018-2329-y>Best regards. Corinne Pomerleau, Ph.D. corinne.pomerleau@umanitoba.ca
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Corinne Pomerleau -
Mafalda dF