Picoeukaryote distribution in relation to nitrate uptake in the oceanic nitracline

Painter, SC; Patey, MD; Tarran, GA; Torres-Valdés, S. 2014 Picoeukaryote distribution in relation to nitrate uptake in the oceanic nitracline. Aquatic Microbial Ecology, 72 (3). 195-213. 10.3354/ame01695

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Official URL: http://dx.doi.org/10.3354/ame01695

Abstract/Summary

We investigated the relationship between picoeukaryote phytoplankton (< 2 mu m) and the deep layer of new production (NO3- uptake) in the nitracline of the eastern subtropical North Atlantic Ocean. Indices of NO3- uptake kinetics obtained within the lower 15 % of the euphotic zone demonstrate that subsurface NO3- uptake maxima are coincident with localised peaks in maximum uptake rates (V-max) and, crucially, with maximum picoeukaryote abundance. The mean rate of NO3- utilization at the nitracline is typically 10-fold higher than in surface waters despite much lower in situ irradiance. These observations confirm a high affinity for NO3-, most likely by the resident picoeukaryote community, and we conservatively estimate mean cellular uptake rates of between 0.27 and 1.96 fmol NO3- cell(-1) h(-1). Greater scrutiny of the taxonomic composition of the picoeukaryote group is required to further understand this deep layer of new production and its importance for nitrogen cycling and export production, given longstanding assumptions that picoplankton do not contribute directly to export fluxes.

Item Type: Publication - Article
Additional Keywords: PACIFIC SUBTROPICAL GYRE; ATLANTIC MERIDIONAL TRANSECT; PHYTOPLANKTON GROWTH-RATES; ORGANIC NITROGEN RELEASE; MIGRATING DIATOM MATS; SARGASSO SEA; NORTH-ATLANTIC; EUPHOTIC ZONE; NANOMOLAR CONCENTRATIONS; COMMUNITY STRUCTURE
Subjects: Ecology and Environment
Marine Sciences
Divisions: Plymouth Marine Laboratory > Science Areas > Cycling in the Sunlit Ocean
Depositing User: Mrs Julia Crocker
Date made live: 14 Oct 2014 12:48
Last Modified: 06 Jun 2017 16:12
URI: http://plymsea.ac.uk/id/eprint/6248

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