[MARMAM] publication

Mark Baumgartner mbaumgartner at whoi.edu
Tue Oct 7 06:33:29 PDT 2008


The following paper was recently published in a special issue of a  
journal that does not typically print marine mammal articles (sad as  
that may be).  I thought some of you may be interested.  The article  
is freely available for download at http://aslo.org/lo/toc/vol_53/ 
issue_5_part_2 or by request to me.

Kind regards,
Mark Baumgartner

Baumgartner, M.F. and D.M. Fratantoni.  2008.  Diel periodicity in  
both sei whale vocalization rates and the vertical migration of their  
copepod prey observed from ocean gliders.  Limnology and Oceanography  
53: 2197-2209.

The daily activity cycles of marine predators may be dictated in  
large part by the timing of prey availability. For example, recent  
studies have observed diel periodicity in baleen whale vocalization  
rates that are thought to be governed by the diel vertical migration  
of their zooplanktonic prey. We addressed this hypothesis by studying  
associations between sei whale (Balaenoptera borealis) vocalization  
rates, oceanographic conditions, and the vertical distribution of the  
whales’ prey, the calanoid copepod Calanus finmarchicus, during May  
2005 in the southwestern Gulf of Maine using an array of autonomous  
ocean gliders. Each of the four gliders was equipped with sensors to  
measure temperature, salinity, and chlorophyll fluorescence. Three of  
the four gliders carried a digital acoustic recorder and the fourth  
carried a 1-MHz acoustic Doppler current profiler. We observed strong  
diel periodicity in the acoustic backscatter measured by the current  
profiler that we attribute (based on a corroborating shipboard study)  
to the diel vertical migration of C. finmarchicus. Sei whale  
vocalization rates also exhibited diel periodicity, with more calls  
detected during the daytime when C. finmarchicus was observed at  
depth. We found no evidence to suggest that the observed patterns in  
sei whale calling rates were attributable to diel periodicity in  
background noise or acoustic propagation conditions. Sei whales are  
adept at foraging on nearsurface aggregations of C. finmarchicus;  
therefore we expect that the whales were feeding at night. We  
hypothesize that calling rates are reduced at night while the whales  
are feeding, but increase with social activity during the day when  
copepods are either more difficult or less efficient to capture at  
depth. The gliders’ persistence during adverse weather conditions  
experienced during the study allowed continuous collocated  
observations of whale vocalization behavior and oceanographic  
conditions that have not been previously possible with traditional  
shipboard techniques.

Mark Baumgartner
Assistant Scientist
Biology Department
Woods Hole Oceanographic Institution
MS #33, Redfield 256
Woods Hole, MA 02543
mbaumgartner at whoi.edu
(508)289-2678 phone
(508)457-2134 fax

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