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Net community production and export from S eaglider measurements in the N orth A tlantic after the spring bloom
Author(s) -
Alkire Matthew B.,
Lee Craig,
D'Asaro Eric,
Perry Mary Jane,
Briggs Nathan,
Cetinić Ivona,
Gray Amanda
Publication year - 2014
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010105
Subject(s) - picoplankton , bloom , diatom , spring bloom , environmental science , advection , plankton , oceanography , phytoplankton , chlorophyll a , particulates , atmospheric sciences , nutrient , biology , geology , ecology , botany , physics , thermodynamics
Mean rates of net community production (NCP) and particulate organic carbon (POC) export were estimated from sensor measurements of dissolved oxygen (O 2 ), chlorophyll fluorescence ( chl F ), and particulate backscatter ( b bp 700 ) collected from three Seagliders that surveyed a 20 × 20 km area in the North Atlantic subsequent to a large diatom bloom. Since the Seagliders sampled geographically fixed patterns, care was taken in the calculation of all terms applicable to the Eulerian reference frame, including local rate of change, vertical mixing, air‐sea exchange, and horizontal advection. Although similar studies of NCP in the open ocean have generally assumed advection to be insignificant, we have found that this term cannot be ignored when dealing with temporal scales of ≤1 month and/or spatial scales ≤20 km. The overlapping sampling pattern of the Seagliders was sufficiently rapid such that 4–5 day time scales observed in the O 2 and POC data were adequately resolved and variations were not a consequence of aliasing spatial variability. During the study period, ratios of chlorophyll fluorescence‐to‐particulate backscatter (chl: b bp 700 ) were lower than values encountered during the spring diatom bloom, suggesting the phytoplankton community was predominantly composed of smaller cells (picoplankton and nanoplankton) and/or coccolithophorids. Coupled budgets of oxygen and POC indicated a net community production of 1.0 mol C m −2 and carbon export of 0.6 mol C m −2 , respectively, over a period of 23 days. Thus, the production and export of carbon that occurred over the month‐long experiment period was comparable to that encountered during the spring bloom.