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Pelagic primary productivity and upper ocean nutrient dynamics across Subarctic and Arctic Seas
Author(s) -
Varela Diana E.,
Crawford David W.,
Wrohan Ian A.,
Wyatt Shea N.,
Carmack Eddy C.
Publication year - 2013
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2013jc009211
Subject(s) - subarctic climate , arctic , photic zone , oceanography , pelagic zone , canada basin , bay , phytoplankton , nutrient , chlorophyll a , tundra , nitrate , new production , environmental science , chemistry , biology , ecology , geology , biochemistry
Phytoplankton and nutrient dynamics were investigated during the 2007 and 2008 summers in the euphotic zone of five broad domains across Subarctic and Arctic Seas: the Eastern Subarctic North Pacific Ocean, ESNP; Bering and Chukchi Seas, BE‐CH; Beaufort Sea and Canada Basin, BS‐CB; Canadian Arctic Archipelago, CAA; and Baffin Bay and Labrador Sea, BB‐LS. Average concentrations of nutrients (NO 3 − , NH 4 + , Si(OH) 4 , and PO 4 3− ) decreased markedly from west to east, with minima in NO 3 − and NH 4 + in surface BS‐CB waters, but relatively invariant urea‐N concentrations across the entire region. In the BS‐CB domain, low uptake rates of nitrate (ρNO 3 − ) and ammonium (ρNH 4 + ) were exceeded by uptake of urea (ρUrea‐N). Whereas average ρNO 3 − was highest in the BE‐CH domain, ρUrea‐N was maximal in BB‐LS. Average depth‐integrated f ‐ratios ranged from 0.27 in the BS‐CB domain to 0.57 in BE‐CH, while chlorophyll a (chl a ) and primary productivity (ρC) were highest in BE‐CH and BB‐LS, and consistently low in the BS‐CB domain. The >5 µm phytoplankton fraction dominated ρC and ρNO 3 − in the BE‐CH and CAA domains, whereas ESNP and BS‐CB were dominated by the <5 µm fraction. In the BB‐LS domain, the larger cells were responsible for ∼50% of ρC, ρNO 3 − , and ρUrea‐N. This study highlights the contrast in ice‐corrected average new production between the BE‐CH (396 mg C m −2 d −1 ) and BS‐CB (5.50 mg C m −2 d −1 ) domains in summer, and the larger contribution of urea‐N uptake to total N uptake in central and eastern regions where NO 3 − concentrations were lower.