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Aquatic Microbial Ecology

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AME 23:205-212 (2001)  -  doi:10.3354/ame023205

Surface water distribution of pico- and nanophytoplankton in relation to two distinctive water masses in the North Water, northern Baffin Bay, during fall

Behzad Mostajir1,*, Michel Gosselin1, Yves Gratton2, Beatrice Booth3, Christophe Vasseur1, Marie-Ève Garneau1, Éric Fouilland1, Francesca Vidussi1, Serge Demers1

1Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
2Institut National de la Recherche Scientifique (INRS-Eau), 2800 rue Einstein, CP 7500, Sainte-Foy, Québec G1V 4C7, Canada
3School of Oceanography, University of Washington, Seattle, Washington 98195, USA
*Present address: CNRS, ERS 2011 ŒEcosystèmes Lagunaires¹, Université Montpellier II, CP 093, Place E. Bataillon, 34095 Montpellier Cedex 5, France. E-mail:

ABSTRACT: Distribution of pico- and nanophytoplankton in surface waters was investigated in relation to environmental factors at 10 stations in the North Water (NOW), northern Baffin Bay, and at 4 more southerly stations in Baffin Bay in fall 1999. Water temperature (T), salinity (S), dissolved inorganic nitrogen (DIN), phosphate concentrations and pico- and nanophytoplankton abundances were measured in the surface waters in the studied area. A clustering analysis was performed on these data and allows 2 major ecological regions to be distinguished. An eastern region was characterized by warmer, more saline, surface waters (T > -0.04°C, 31.1 < S < 32.7) where the picophytoplankton (eukaryotic flagellates, prasinophyte) were more abundant (700 to 4000 cells ml-1). The distribution of picophytoplankton in the NOW was directly correlated with the surface water T and S. Another region, the northwestern, was characterized by colder, less saline, surface waters (T < -1.2°C, 29.3<S<31.0), can be divided into northern and western sub-regions. Nanophytoplankton (mostly diatoms) were more abundant (>3000 cells ml-1) in the northern sub-region and their distributions followed the change in DIN concentrations. DIN and phosphate concentrations were higher in the northern sub-region than in the eastern region and the western sub-region, although DIN and phosphate concentrations were low in the NOW, with values ranging from 0.1 to 1.0 and 0.09 to 0.69 μM, respectively. Based on these ecological results, it is hypothesized that a surface current flows northward along the western coast of Greenland in fall, bringing warm, more saline water to the eastern part of the NOW. In contrast, surface Arctic water (colder, less saline) coming from the Kane Basin flows southward along the western part of the NOW. These 2 distinct water masses, with their different physical and chemical characteristics, govern pico- and nanophytoplankton distributions in the NOW during the fall.

KEY WORDS: Picophytoplankton·Nanophytoplankton·Arctic· Polynya · Water temperature · Dissolved inorganic nitrogen

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