Phytoplankton biomass cycles in the North Atlantic subpolar gyre: A similar mechanism for two different blooms in the Labrador Sea

An analysis of seasonal variations in climatological surface chlorophyll points to distinct biogeographical zones in the North Atlantic subpolar gyre. In particular, the Labrador Sea appears well delineated into two regions on either side of the 60°N parallel, with very different climatological phyt...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Lacour, Léo, Claustre, Hervé, Prieur, Louis, D'Ortenzio, Fabrizio
Format: Article in Journal/Newspaper
Language:English
Published: AGU (American Geophysical Union) 2015
Subjects:
Online Access:https://oceanrep.geomar.de/id/eprint/34436/
https://oceanrep.geomar.de/id/eprint/34436/1/grl53105.pdf
https://doi.org/10.1002/2015GL064540
Description
Summary:An analysis of seasonal variations in climatological surface chlorophyll points to distinct biogeographical zones in the North Atlantic subpolar gyre. In particular, the Labrador Sea appears well delineated into two regions on either side of the 60°N parallel, with very different climatological phytoplankton biomass cycles. Indeed, north of 60°N, an early and short spring bloom occurs in late April, while south of 60°N, the bloom gradually develops 1 month later and significant biomass persists all summer long. Nevertheless, at climatological scale, the first-order mechanism that controls the bloom is identical for both bioregions. The light-mixing regime can explain the bloom onset in both bioregions. In the Labrador Sea, the blooms seem to rely on a mean community compensation irradiance threshold value of 2.5 mol photon m−2 d−1 over the mixed layer.