Microbial community structure at the U.S.‐Joint Global Ocean Flux Study Station ALOHA: Inverse methods for estimating biochemical indicator ratios

Christian, James R.; Karl, David M.

doi:10.1029/94jc00681

Cited by 85 publications

(62 citation statements)

References 50 publications

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“…In the present study, we used 1.5 kg C per mol leucine incorporated, assuming no isotopic dilution, and a low carbon per cell conversion factor specific for oligotrophic environments (10 fg C per cell, Christian and Karl, 1994;Fukuda et al, 1998). The application of these conversion factors allowed us to compare our bacterial community turnover rates (0.05-0.21 d −1 , Table 4, mean 0.11±0.03 d −1 , n=63) with many previous studies that used 3.1 kgC per mol leucine and 20 fg C per cell (Li et al, 1993;Kirchman et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

Heterotrophic bacterial production in the eastern South Pacific: longitudinal trends and coupling with primary production

et al. 2008

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In the gyre (120 • W, 22 • S) records of low phytoplankton biomass (7 mg Total Chla m −2 ) were obtained and fluxes of in situ 14 C-based particulate primary production were as low as 153 mg C m −2 d −1 , thus equal to the value considered as a limit for primary production under strong oligotrophic conditions. Average rates of 3 H leucine incorporation rates, and leucine incorporation rates per cell (5-21 pmol l −1 h −1 and 15-56×10 −21 mol cell −1 h −1 , respectively) determined in the South Pacific gyre, were in the same range as those reported for other oligotrophic subtropical and temperate waters. Fluxes of dark community respiration, determined at selected stations across the transect varied in a narrow range (42-97 mmol O 2 m −2 d −1 ), except for one station in the upwelling off Chile (245 mmol O 2 m −2 d −1 ). Bacterial growth

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Section: Discussionmentioning

confidence: 99%

Heterotrophic bacterial production in the eastern South Pacific: longitudinal trends and coupling with primary production

et al. 2008

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“…BP estimated using either approach also requires another factor to derive biomass production (usually as carbon). Various literature values for the mass of carbon per cell have been employed for this purpose (Caron et al 1995;Christian and Karl 1994). Li et al (1993) and both used 20 fgC cell Ϫ1 (1 fg ϭ 10 Ϫ15 g), and that value is used here for consistency.…”

Section: Methodsmentioning

confidence: 99%

The magnitude of spring bacterial production in the North Atlantic Ocean

Ducklow

Kirchman

Anderson

2002

Limnology & Oceanography

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Dissolved organic carbon (DOC), a major reservoir in the ocean carbon cycle, is produced by a profusion of plankton sources and processes but is consumed mainly by bacterioplankton. Thus bacterial metabolism regulates the entry of DOC into the longer scale global carbon cycle. Bacterial production (BP) is the routinely measured quantity for evaluating the roles of bacteria in carbon cycling. However BP cannot be measured directly and instead is estimated from related metabolic processes requiring the use of poorly constrained conversion factors. BP, and thus the total carbon utilization, are potentially uncertain by a factor of two or more. In the North Atlantic Bloom Experiment (NABE), BP was estimated to be about 30% of the simultaneous particulate primary production (PP), with some daily estimates exceeding 50%. Here we reassess these estimates, synthesizing knowledge and understanding of plankton dynamics gained since the 1989 NABE study. Daily BP derived from six different conversion factors averaged 20% of PP but ranged from 3 to 68%. The coupling of BP to PP was not consistent with either short-term cycling of labile DOC (hours) nor with much longer term cycling of semilabile DOC (seasons). Trophodynamic processes, including release of DOC from phytoplankton, by themselves could have maintained BP at about 15% of PP. Use of decomposing POC or previously accumulated semilabile DOC could each have supported some additional increment of BP for brief periods. Both reconsideration of observations and model results indicated that higher estimates of BP exceeding 20% of PP could not be supported without extraordinary and prolonged inputs of allochthonous carbon. Recent assertions of high BP in the tropics and other oceanic regimes should be considered carefully, especially if external subsidies are not obvious.

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“…V sp DIP corresponds to the V DIP to PartP ratio, V sp DIC corresponds to the V DIC to AB ratio, HBP:HBB corresponds to the HBP to HBB ratio. A conversion factor of 10 fgC cell −1 (Christian and Karl, 1994;Caron et al, 1995) has been used to convert heterotrophic bacterial abundance (counted by flow cytometry) to C equivalent. AB has been calculated using two methods.…”

Section: Specific Uptake Rate Estimatesmentioning

confidence: 99%

Growth and specific P-uptake rates of bacterial and phytoplanktonic communities in the Southeast Pacific (BIOSOPE cruise)

et al. 2007

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Abstract. Predicting heterotrophic bacteria and phytoplankton specific growth rates (µ) is of great scientific interest. Many methods have been developed in order to assess bacterial or phytoplankton µ. One widely used method is to estimate µ from data obtained on biomass or cell abundance and rates of biomass or cell production. According to Kirchman (2002), the most appropriate approach for estimating µ is simply to divide the production rate by the biomass or cell abundance estimate. Most methods using this approach to estimate µ are based on carbon (C) incorporation rates and C biomass measurements. Nevertheless it is also possible to estimate µ using phosphate (P) data. We showed that particulate phosphate (PartP) can be used to estimate biomass and that the P uptake rate to PartP ratio can be employed to assess µ. Contrary to other methods using C, this estimator does not need conversion factors and provides an evaluation of µ for both autotrophic and heterotrophic organisms. We report values of P-based µ in three size fractions (0.2-0.6; 0.6-2 and >2 µm) along a Southeast Pacific transect, over a wide range of P-replete trophic status. P-based µ values were higher in the 0.6-2 µm fraction than in the >2 µm fraction, suggesting that picoplankton-sized cells grew faster than the larger cells, whatever the trophic regime encountered. Picoplankton-sized cells grew significantly faster in the deep chlorophyll maximum layer than in the upper part of the photic zone in the oligotrophic gyre area, suggesting that picoplankton might outcompete >2 µm cells in this particular high-nutrient, low-light environment. P-based µ attributed to free-living bacteria (0.2-0.6 µm) and picoplankton (0.6-2 µm) size-fractions were relatively low (0.11±0.07 d −1 and Correspondence to: S. Duhamel (solange.duhamel@univmed.fr) 0.14±0.04 d −1 , respectively) in the Southeast Pacific gyre, suggesting that the microbial community turns over very slowly.

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Microbial community structure at the U.S.‐Joint Global Ocean Flux Study Station ALOHA: Inverse methods for estimating biochemical indicator ratios

Cited by 85 publications

References 50 publications

Heterotrophic bacterial production in the eastern South Pacific: longitudinal trends and coupling with primary production

Heterotrophic bacterial production in the eastern South Pacific: longitudinal trends and coupling with primary production

The magnitude of spring bacterial production in the North Atlantic Ocean

Growth and specific P-uptake rates of bacterial and phytoplanktonic communities in the Southeast Pacific (BIOSOPE cruise)

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