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Biogeosciences Discuss., 9, 6445-6488, 2012
www.biogeosciences-discuss.net/9/6445/2012/ doi:10.5194/bgd-9-6445-2012 © Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License. |
Nutritive and photosynthetic ecology of subsurface chlorophyll maxima in the Canadian Arctic waters
1Québec-Océan & Département de biologie, Université Laval, Québec, QC, G1V 0A6, Canada
2Department of Biology, McGill University, Montréal, Québec, QC, H3A 1B1, Canada
Abstract. Assessments of carbon and nitrogen (N) assimilation in Canadian Arctic waters confirmed the large contribution of subsurface chlorophyll maxima (SCM) to total water-column production from spring to late fall. Although SCM communities showed acclimation to low irradiance and greater nitrate (NO3−) availability, their productivity was generally limited by light and temperature. During spring-early summer, most of the primary production at the SCM was sustained by NO3−, with a f-ratio (i.e. relative contribution of NO3− uptake to total N uptake) of 0.74 ± 0.26 on average. The seasonal decrease in NO3− availability and irradiance, coupled to the build up of ammonium (NH4+), favoured a transition toward a predominantly regenerative system (f-ratio = 0.37 ± 0.20). Results emphasize the need to include SCM in remote-sensing algorithms and to revisit ecosystem model parameters in highly stratified environments such as the Canadian Arctic waters.
Citation: Martin, J., Tremblay, J.-É., and Price, N. M.: Nutritive and photosynthetic ecology of subsurface chlorophyll maxima in the Canadian Arctic waters, Biogeosciences Discuss., 9, 6445-6488, doi:10.5194/bgd-9-6445-2012, 2012.