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Marine Ecology Progress Series

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MEPS 345:13-26 (2007)  -  DOI:

New and regenerated production during a late summer bloom in an Arctic polynya

Marie-Ève Garneau1,4,*, Michel Gosselin1, Bert Klein2,5, Jean-Éric Tremblay2, Eric Fouilland3

1Institut des sciences de la mer (ISMER), Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
2Québec-Océan, Département de Biologie, Université Laval, Québec, Québec G1K 7P4, Canada
3Écosystèmes Lagunaires, CNRS-UMR 5119, Université Montpellier II, Case 093, Place E. Bataillon, 34095 Montpellier Cedex 5, France
4Centre d’etudes nordiques, Pavillon Abitibi-Price, Room 1202, Université Laval, Québec, Québec G1K 7P4, Canada
5Present address: 2063 rue Bourbonnière, Sillery, Québec G1T 1A9, Canada

ABSTRACT: New and regenerated production were estimated from nitrate, ammonium and urea uptake in the highly productive North Water region (NOW, northern Baffin Bay) during the late summer bloom and its decline in early autumn 1999. Nitrogen uptake rates decreased due to a significant 4-fold reduction of the average irradiance in the euphotic zone between these 2 periods. Nitrate availability also regulated the relative uptake of nitrate (ratio of nitrate uptake to total nitrogen uptake, or f-ratio) over spatial scales in early autumn. Stations located along the Greenland coast, which had relatively warm (–0.5°C) and saline (32.5) waters, had higher nitrate concentrations (153 vs. 51 mmol N m–2) and f-ratios (0.36 vs. 0.16) than those of stations located on the Canadian side, where the euphotic zone was relatively colder (–1.4°C) and less saline (30.6). The f-ratios were also corrected for nitrogen uptake by heterotrophic bacteria using the results from experiments that employed specific metabolic inhibitors. The corrected f-ratio range of 0.24 to 0.41 considered only the fraction of the nitrogen uptake due to phytoplankton in order to obtain a more accurate estimate of new production. Based on this range, new production varied from 203 to 346 and 85 to 145 mg C m–2 d–1 in late summer and early autumn, respectively. For the entire sampling period, averaged new production was 132 to 228 mg C m–2 d–1; however, when the dissolved form was included, we estimated that new production may double to between 262 and 452 mg C m–2 d–1. This estimate illustrates that dissolved forms can be significant and need to be considered. When combining our results with those from the literature, new production in the NOW in 1998–99 amounted to between 143 and 152 g C m–2 yr–1, suggesting that 60% of the total annual primary production may potentially be exported from the euphotic zone. This study completes the first annual time series of new production in a high-latitude ecosystem.

KEY WORDS: Late summer bloom · Nitrogen uptake rate · New production · Export carbon production · North Water Polynya

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Cite this article as: Garneau M, Gosselin M, Klein B, Tremblay J, Fouilland E (2007) New and regenerated production during a late summer bloom in an Arctic polynya. Mar Ecol Prog Ser 345:13-26.

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