MEPS 442:11-22 (2011)  -  DOI: https://doi.org/10.3354/meps09343

Phytoplankton growth and microzooplankton grazing along a sub-Arctic fjord (Godthåbsfjord, west Greenland)

Albert Calbet1,*, Karen Riisgaard2, Enric Saiz1, Sara Zamora1, Colin Stedmon3,5, Torkel Gissel Nielsen2,4

1Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta 37−49, 08003 Barcelona, Spain
2National Institute of Aquatic Resources, DTU Aqua, Section for Ocean Ecology and Climate, Technical University of Denmark, Kavalergården 6, 2920 Charlottenlund, Denmark
3National Environmental Research Institute, Department of Marine Ecology, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
4Greenland Climate Research Center, Greenland Institute of Natural Resources, Kivioq 2, PO Box 570, 3900 Nuuk, Greenland
5Present address: National Institute of Aquatic Resources, DTU Aqua, Section for Ocean Ecology and Climate, Technical University of Denmark, Kavalergården 6, 2920 Charlottenlund, Denmark

ABSTRACT: We evaluated the role of microzooplankton (sensu latto, grazers <500 µm) in determining the fate of phytoplankton production (PP) along a glacier-to-open sea transect in the Greenland subarctic fjord, Godthåbfjord. Based on the distribution of size fractionated chlorophyll a (chl a) concentrations we established 4 zones: (1) Fyllas Bank, characterized by deep chl a maxima (ca. 30 to 40 m) consisting of large cells, (2) the mouth and main branch of the fjord, where phytoplankton was relatively homogeneously distributed in the upper 30 m layer, (3) inner waters influenced by glacial melt water and upwelling, with high chl a concentrations (up to 12 µg l−1) in the >10 µm fraction within a narrow (2 m) subsurface layer, and (4) the Kapisigdlit branch of the fjord, ice-free, and characterized with a thick and deep chl a maximum layer. Overall, microzooplankton grazing impact on primary production was variable and seldom significant in the Fyllas Bank and mouth of the fjord, quite intensive (up to >100% potential PP consumed daily) in the middle part of the main and Kapisigdlit branches of the fjord, and rather low and unable to control the fast growing phytoplankton population inhabiting the nutrient rich waters in the upwelling area in the vicinity of the glacier. Most of the grazing impact was on the <10 µm phytoplankton fraction, and the major grazers of the system seem to be >20 µm microzooplankton, as deducted from additional dilution experiments removing this size fraction. Overall, little or no export of phytoplankton out of the fjord to the Fyllas Bank can be determined from our data.


KEY WORDS: West Greenland coast · Sub-Arctic fjord · Plankton community structure · Microzooplankton · Grazing


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Cite this article as: Calbet A, Riisgaard K, Saiz E, Zamora S, Stedmon C, Nielsen TG (2011) Phytoplankton growth and microzooplankton grazing along a sub-Arctic fjord (Godthåbsfjord, west Greenland). Mar Ecol Prog Ser 442:11-22. https://doi.org/10.3354/meps09343

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