MEPS 524:11-26 (2015)  -  DOI: https://doi.org/10.3354/meps11189

Effect of continental shelf canyons on phytoplankton biomass and community composition along the western Antarctic Peninsula

M. T. Kavanaugh1,*, F. N. Abdala2, H. Ducklow3, D. Glover1, W. Fraser4, D. Martinson5, S. Stammerjohn6, O. Schofield7, S. C. Doney1

1Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, MS 25, 266 Woods Hole Road, Woods Hole, Massachusetts 02543, USA
2Ecologia de Fitoplâncton e Microorganismos Marinhos, Federal University Rio Grande, Brazil
3Earth and Environmental Sciences, Lamont Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA
4Polar Oceans Research Group, Sheridan, Montana 59749, USA
5Division of Ocean and Climate Physics, Lamont Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA
6Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309, USA
7Institute of Marine and Coastal Sciences, Rutgers University, Rutgers, New Jersey 08901, USA
*Corresponding author:

ABSTRACT: The western Antarctic Peninsula is experiencing dramatic climate change as warm, wet conditions expand poleward and interact with local physics and topography, causing differential regional effects on the marine ecosystem. At local scales, deep troughs (or canyons) bisect the continental shelf and act as conduits for warm Upper Circumpolar Deep Water, with reduced seasonal sea ice coverage, and provide a reservoir of macro- and micronutrients. Shoreward of many canyon heads are Adélie penguin breeding colonies; it is hypothesized that these locations reflect improved or more predictable access to higher biological productivity overlying the canyons. To synoptically assess the potential impacts of regional bathymetry on the marine ecosystem, 4 major canyons were identified along a latitudinal gradient west of the Antarctic Peninsula using a high-resolution bathymetric database. Biological-physical dynamics above and adjacent to canyons were compared using in situ pigments and satellite-derived sea surface temperature, sea ice and ocean color variables, including chlorophyll a (chl a) and fucoxanthin derived semi-empirically from remote sensing reflectance. Canyons exhibited higher sea surface temperature and reduced sea ice coverage relative to adjacent shelf areas. In situ and satellite-derived pigment patterns indicated increased total phytoplankton and diatom biomass over the canyons (by up to 22 and 35%, respectively), as well as increases in diatom relative abundance (fucoxanthin:chl a). While regional heterogeneity is apparent, canyons appear to support a phytoplankton community that is conducive to both grazing by krill and enhanced vertical export, although it cannot compensate for decreased biomass and diatom relative abundance during low sea ice conditions.


KEY WORDS: Western Antarctic Peninsula · Canyons · Phytoplankton · Diatoms · Remote sensing · Adélie penguin habitat · Sea ice


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Cite this article as: Kavanaugh MT, Abdala FN, Ducklow H, Glover D and others (2015) Effect of continental shelf canyons on phytoplankton biomass and community composition along the western Antarctic Peninsula. Mar Ecol Prog Ser 524:11-26. https://doi.org/10.3354/meps11189

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