MEPS 492:253-272 (2013)  -  doi:10.3354/meps10534

Carbon fluxes and pelagic ecosystem dynamics near two western Antarctic Peninsula Adélie penguin colonies: an inverse model approach

Sévrine F. Sailley1,6,*, Hugh W. Ducklow2, Holly V. Moeller1,7, William R. Fraser3, Oscar M. Schofield4, Deborah K. Steinberg5, Lori M. Garzio5, Scott C. Doney1

1Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
2Lamont-Doherty Earth Observatory, Palisades, New York 10964, USA
3Polar Oceans Research Group, PO Box 368, Sheridan, Montana 59749, USA
4Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey 08901, USA
5Virginia Institute of Marine Science, Gloucester Pt., Virginia 23062, USA
6Present address: Plymouth Marine Laboratory, Plymouth, PL13DH, UK
7Present address: Stanford University, Stanford, California 09425, USA

ABSTRACT: An inverse food-web model for the western Antarctic Peninsula (WAP) pelagic food web was constrained with data from Palmer Long Term Ecological Research (PAL-LTER) project annual austral summer sampling cruises. Model solutions were generated for 2 regions with Adélie penguin Pygoscelis adeliae colonies presenting different population trends (a northern and a southern colony) for a 12 yr period (1995-2006). Counter to the standard paradigm, comparisons of carbon flow through bacteria, microzooplankton, and krill showed that the diatom-krill-top predator food chain is not the dominant pathway for organic carbon exchanges. The food web is more complex, including significant contributions by microzooplankton and the microbial loop. Using both inverse model results and network indices, it appears that in the northern WAP the food web is dominated by the microbial food web, with a temporal trend toward its increasing importance. The dominant pathway for the southern WAP food web varies from year to year, with no detectable temporal trend toward dominance of microzooplankton versus krill. In addition, sensitivity analyses indicated that the northern colony of Adélie penguins, whose population size has been declining over the past 35 yr, appears to have sufficient krill during summer to sustain its basic metabolic needs and rear chicks, suggesting the importance of other processes in regulating the Adélie population decline.

KEY WORDS: Inverse model · Food web · Antarctica · Microzooplankton · Krill · Ecosystem state change · Climate change

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Cite this article as: Sailley SF, Ducklow HW, Moeller HV, Fraser WR and others (2013) Carbon fluxes and pelagic ecosystem dynamics near two western Antarctic Peninsula Adélie penguin colonies: an inverse model approach. Mar Ecol Prog Ser 492:253-272

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