MEPS 572:19-42 (2017)  -  DOI: https://doi.org/10.3354/meps12125

ABSTRACT: Protist (>2 µm) taxonomic composition was investigated for the first time in 4 Labrador fjords (Nachvak, Saglek, Okak and Anaktalak) during summers 2007 and 2013, early fall 2010 and late fall 2009. Protist composition was significantly different from one season to another. Significant spatial differences in protist composition were found only during summer 2013. During summer 2007, the community was characterized by diatoms and a mixed assemblage of flagellates. In summer 2013, flagellates largely dominated the community, and an intense Phaeocystis pouchetii bloom was observed in Nachvak Fjord (18 × 10⁶ cells l^-1). In autumn, the community was dominated by unidentified flagellates, prymnesiophytes and diatoms, in various proportions from early to late fall. From a summer situation characterized by stronger stratification, higher incident irradiance and depleted nutrients in surface waters, it evolved to an autumn situation characterized by decreasing air temperature and irradiance associated with an environmental forcing (e.g. weather) allowing cooling and greater vertical mixing of the water column. Combining our observations with those from the literature, we suggest the following annual succession in the Labrador fjord phytoplankton community: (winter) dinoflagellates and small flagellated cells—(spring) Fragilariopsis spp., Chaetoceros spp., Thalassiosira spp. and Phaeocystis pouchetii—(summer) Chaetoceros spp., P. pouchetii and Chrysochromulina spp.—(fall) Gymnodinium/Gyrodinium spp., Chrysochromulina spp. and other flagellates. Overall, the protist richness was 2 times higher in fall than in summer, the highest richness being observed in early fall, with 201 taxonomic entries, 72 genera and 131 species identified.

KEY WORDS: Taxonomic composition · Protists · Phytoplankton · Diatoms · Phaeocystis · Seasonal variability · Northeastern Canada · Labrador · Fjords

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Cite this article as: Simo-Matchim AG, Gosselin M, Poulin M, Ardyna M, Lessard S (2017) Summer and fall distribution of phytoplankton in relation to environmental variables in Labrador fjords, with special emphasis on Phaeocystis pouchetii . Mar Ecol Prog Ser 572:19-42. https://doi.org/10.3354/meps12125 Export citation Share:    Facebook - - linkedIn