[MARMAM] New Publication: Intraseasonal variation in southeast Pacific blue whale acoustic presence, zooplankton backscatter, and oceanographic variables on a feeding ground in Northern Chilean Patagonia

Susannah Buchan sjbuchan at gmail.com
Fri Nov 12 08:14:25 PST 2021


Dear colleagues,
We are pleased to announce the publication of our study entitled
"*Intraseasonal
variation in southeast Pacific blue whale acoustic presence, zooplankton
backscatter, and oceanographic variables on a feeding ground in Northern
Chilean Patagonia*" in Progress in Oceanography.

Authors:  Buchan Susannah J, Pérez-Santos Iván, Narváez Diego, Castro
Leonardo, Stafford Kathleen M., Baumgartner Mark F., Valle-Levinson
Arnoldo, Montero Paulina, Gutiérrez Laura, Rojas Constanza, Daneri
Giovanni, Neira Sergio

The Abstract can be found below and the full open source paper at:
https://www.sciencedirect.com/science/article/pii/S0079661121001920?via%3Dihub

For any further information, please email: sjbuchan at gmail.com.

Kind regards,
Susannah

___________________________________________________________
Abstract:

Seasonal variation in the acoustic presence of blue whale calls has been
widely reported for feeding grounds worldwide, however variation over the
submonthly scale (several days to <1 month) has been examined to a much
lesser extent. This study combines passive acoustic, hydroacoustic, and *in
situ* oceanographic observations collected at a mooring in the Corcovado
Gulf, Northern Chilean Patagonia, from January 2016-February 2017, to
examine the temporal variation in blue whale acoustic occurrence and prey
backscatter over seasonal and  submonthly scales. Time series data for a)
Southeast Pacific blue whale song calls and D-calls, b) zooplankton
backscatter, c) tidal amplitude, and d) meridional and zonal wind stress
were examined visually for seasonal trends. To examine submonthly
timescales over the summer feeding season (January-June), wavelet
transforms and wavelet coherence were applied; generalized linear models
(GLM) were also applied. There was a 3-month lag between the seasonal
onsets of high zooplankton backscatter (October) and blue whale acoustic
presence (January), and an almost immediate drop in blue whale acoustic
presence with the seasonal decrease of backscatter (June). This may be due
to the use of memory by animals when timing their arrival on the feeding
ground, but the timing of their departure may be related to detection of
low prey availability. Over the summer feeding season, blue whale acoustic
presence was strongly associated with zooplankton backscatter (GLM
coefficient p<<0.0001). Song calls followed a seasonal cycle, but D-calls
appeared to respond to short term variations in environmental conditions
over submonthly scales. Results suggest that spring tides may increase prey
aggregation and/or transport into the Corcovado Gulf, leading to increased
blue whale acoustic presence over 15-day or 30-day cycles; and short-lived
events of increased wind stress with periodicities of 2-8 days and 16-30
days, may also contribute to the aggregation of prey. We discuss the
strengths and limitations of coupling passive and active acoustic data to
examine drivers of blue whale distribution.

-- 
Susannah J. Buchan, PhD
Associate Researcher, COPAS Sur-Austral & Visiting Professor, University of
Concepción, Chile
Associate Researcher, CEAZA Research Center, Chile
Guest Investigator, Woods Hole Oceanographic Institution, USA
Email: sbuchan at udec.cl/sjbuchan at gmail.com
Cel. Chile: +56 9 6646 8466/ Cel. España: +34 695 06 62 24
https://orcid.org/0000-0003-2180-1432
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