| Summary: | 13 pages, 6 figures, 5 tables Surface distribution (0–100 m) of zooplankton biomass and specific aminoacyltRNA synthetases (AARS) activity, as a proxy of structural growth, were assessed during winter 2002 and spring 2004 in the Labrador Sea. Two fronts formed by strong boundary currents, several anticyclonic eddies and a cyclonic eddy were studied. The spatial contrasts observed in seawater temperature, salinity and fluorescence, associated with those mesoscale structures, affected the distributions of both zooplankton biomass and specific AARS activity, particularly those of the smaller individuals. Production rates of large organisms (200–1000 mm) were significantly related to microzooplankton biomass (63–200 mm), suggesting a cascade effect from hydrography through microzooplankton to large zooplankton.Water masses defined the biomass distribution of the three dominant species: Calanus glacialis was restricted to cold waters on the shelves while Calanus hyperboreus and Calanus finmarchicus were widespread from Canada to Greenland. Zooplankton production was up to ten-fold higher inside anticyclonic eddies than in the surrounding waters. The recent warming tendency observed in the Labrador Sea will likely generate weaker convection and less energetic mesoscale eddies. This may lead to a decrease in zooplankton growth and production in the Labrador basin This work was funded by the Spanish Ministry of Education, Culture and Sport grant to L. Yebra (EX-2002-0456), and by the NERC Marine Productivity Thematic Programme (Grants NER/T/S/2001/01256 and NE/C508418/1). This work is a contribution to the Plymouth Marine Laboratory Core Strategic Research Programme and to the Marine Productivity UK-GLOBEC Programme. Completion of this work was funded by the European Social Fund (I3P programme, CSIC) Peer reviewed
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