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Is seasonal net community production in the South Pacific Subtropical Gyre anomalously low?
Author(s) -
Bender Michael L.,
Jönsson Bror
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl070220
Subject(s) - photic zone , ocean gyre , hydrography , oceanography , subtropics , mixed layer , new production , environmental science , geology , climatology , atmospheric sciences , phytoplankton , nutrient , ecology , biology
The region of the South Pacific Subtropical Gyre (SPSG) at 20°–30°S, 140°–110°W is the oceanic area with the lowest chlorophyll concentration and the deepest nutricline, O 2 saturation horizon, and euphotic zone. We analyze the limited available data from this region to determine if rates of net community production (NCP) are systematically lower than elsewhere. We present limited mixed layer O 2 /Ar data constraining mixed layer NCP, examine hydrographic data from the CLIVAR repeat hydrography P18 line to assess seasonal dissolved inorganic carbon drawdown, and review results from the literature. While it is not possible to formalize uncertainties, the evidence suggests that euphotic zone NCP is around the lower end (~1 mol m −2 yr −1 ) of rates observed elsewhere. However, NCP is shifted to unusually deep depths, a change enabled by the very low extinction coefficients of these waters.