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Biological productivity along Line P in the subarctic northeast Pacific: In situ versus incubation‐based methods
Author(s) -
Giesbrecht Karina E.,
Hamme Roberta C.,
Emerson Steven R.
Publication year - 2012
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2012gb004349
Subject(s) - subarctic climate , productivity , incubation , primary production , environmental science , in situ , mixed layer , primary productivity , new production , oceanography , chemistry , zoology , atmospheric sciences , nutrient , biology , phytoplankton , ecology , geology , ecosystem , biochemistry , organic chemistry , economics , macroeconomics
We compared net community production determined from an in situ O 2 /Ar mass balance (O 2 /Ar‐NCP) with incubation measurements of new and primary production in the subarctic northeast Pacific. In situ O 2 /Ar‐NCP was strongly correlated to new production from 24‐h 15 NO 3 − uptake integrated over the mixed layer ( 15 N‐NewP), if measurements were separated into high and low‐productivity conditions. Under high‐productivity conditions, O 2 /Ar‐NCP estimates were similar to 15 N‐NewP, whereas under low productivity conditions O 2 /Ar‐NCP was up to two times higher than 15 N‐NewP. The relationship between O 2 /Ar‐NCP and 24‐h 13 C primary production ( 13 C‐PP) was more variable, but with a consistent mean O 2 /Ar‐NCP: 13 C‐PP ratio of 0.52 ± 0.17 when only low‐productivity, summer measurements were considered. This relationship with primary production is perturbed by high productivity events such as a late‐summer, iron‐stimulated bloom observed at the offshore stations. Finally, we show that diapycnal mixing usually dominates the O 2 /Ar mass balance in winter in the subarctic Pacific, preventing the determination of NCP by the O 2 /Ar method at that time, except for one unusual stratification event in February 2007.