Nutritive and photosynthetic ecology of subsurface chlorophyll maxima in Canadian Arctic waters

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 (NO 3 − )...

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Bibliographic Details
Published in:Biogeosciences
Main Authors: J. Martin, J. É. Tremblay, N. M. Price
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2012
Subjects:
Online Access:https://doi.org/10.5194/bg-9-5353-2012
https://doaj.org/article/728eb0f4ee5844be9c86dc7a8c0d08a2
Description
Summary: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 (NO 3 − ) availability, their productivity was generally constrained by light and temperature. During spring–early summer, most of the primary production at the SCM was sustained by NO 3 − , with an average f -ratio (i.e., relative contribution of NO 3 − uptake to total N uptake) of 0.74 ± 0.26. The seasonal decrease in NO 3 − availability and irradiance, coupled to the build up of ammonium (NH 4 + ), favoured a transition toward a predominantly regenerative system ( f -ratio = 0.37 ± 0.20) during late summer and fall. Results emphasize the need to adequately consider SCM when estimating primary production and to revisit ecosystem model parameters in highly stratified Arctic waters.