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Estimation of bacterial respiration and growth efficiency in the Ross Sea, Antarctica

Estimation of bacterial respiration and growth efficiency in the Ross Sea, Antarctica
Estimation of bacterial respiration and growth efficiency in the Ross Sea, Antarctica
Seawater cultures were conducted in large volume (36 1) gas impermeable tri-laminate bags for the purpose of empirically deriving bacterial growth efficiency (BGE) and carbon conversion factors (CCF) in the south central Ross Sea. This experimental design allowed for concomitant measurements of metabolic reactants (loss of total and dissolved organic carbon [TOC and DOC]) and products (gain of total carbon dioxide [TCOz] and bacterial biomass) to be made from a single incubation vessel. Some previous studies have relied on proxy measurements (e.g. 02, 3H-thymidine incorporation and cell abundance) to determine BGE and CCF rather than direct carbon measurements. Our experimental design enabled a complete carbon budget to be constructed and eliminated variability associated with normally employed parallel bottle incubations. Uhlization of TOC was well balanced by the production of TC02, in 7 of 8 experiments, validating the use of tri-laminate bags for measuring microbial respiration. In 3 experiments, where TOC, DOC, TCOz and bacterial biovolume were directly measured, carbon mass balance yielded BGE estimates of 12, 32 and 38% and bacterial CCF of 77, 95 and 134 fg C pm-3. In experiments where independent DOC measurements were not made we used our empirically derived CCF values to determine bacterial carbon production and calculated DOC concentrations and BGE for these remaining experiments. The BGE derived from all the bag experiments conducted throughout the austral spring and summer 1995-1997 ranged from 9 to 38%. Our experimental design and carbon mass balance approach could be applied to other aquatic systems to empirically derive the BGE and CCF, factors essential for determining carbon flux through bacterioplankton.
DOC remineralization, Bacterial respiration, TCOz, Growth efficiency, Carbon conversion factor, Tri-laminate bags, Seawater culture
0948-3055
229-244
Carlson, Craig A.
91c79d89-d22c-4a56-9927-06fb50d2ef59
Bates, Nick R.
954a83d6-8424-49e9-8acd-e606221c9c57
Ducklow, Hugh W.
5cac79f8-e06e-4703-aa87-6942b63c32bb
Hansell, Dennis A.
d4f0a3af-ca20-4791-a794-e52cbd56d654
Carlson, Craig A.
91c79d89-d22c-4a56-9927-06fb50d2ef59
Bates, Nick R.
954a83d6-8424-49e9-8acd-e606221c9c57
Ducklow, Hugh W.
5cac79f8-e06e-4703-aa87-6942b63c32bb
Hansell, Dennis A.
d4f0a3af-ca20-4791-a794-e52cbd56d654

Carlson, Craig A., Bates, Nick R., Ducklow, Hugh W. and Hansell, Dennis A. (1999) Estimation of bacterial respiration and growth efficiency in the Ross Sea, Antarctica. Aquatic Microbial Ecology, 19 (3), 229-244.

Record type: Article

Abstract

Seawater cultures were conducted in large volume (36 1) gas impermeable tri-laminate bags for the purpose of empirically deriving bacterial growth efficiency (BGE) and carbon conversion factors (CCF) in the south central Ross Sea. This experimental design allowed for concomitant measurements of metabolic reactants (loss of total and dissolved organic carbon [TOC and DOC]) and products (gain of total carbon dioxide [TCOz] and bacterial biomass) to be made from a single incubation vessel. Some previous studies have relied on proxy measurements (e.g. 02, 3H-thymidine incorporation and cell abundance) to determine BGE and CCF rather than direct carbon measurements. Our experimental design enabled a complete carbon budget to be constructed and eliminated variability associated with normally employed parallel bottle incubations. Uhlization of TOC was well balanced by the production of TC02, in 7 of 8 experiments, validating the use of tri-laminate bags for measuring microbial respiration. In 3 experiments, where TOC, DOC, TCOz and bacterial biovolume were directly measured, carbon mass balance yielded BGE estimates of 12, 32 and 38% and bacterial CCF of 77, 95 and 134 fg C pm-3. In experiments where independent DOC measurements were not made we used our empirically derived CCF values to determine bacterial carbon production and calculated DOC concentrations and BGE for these remaining experiments. The BGE derived from all the bag experiments conducted throughout the austral spring and summer 1995-1997 ranged from 9 to 38%. Our experimental design and carbon mass balance approach could be applied to other aquatic systems to empirically derive the BGE and CCF, factors essential for determining carbon flux through bacterioplankton.

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More information

Published date: 27 October 1999
Keywords: DOC remineralization, Bacterial respiration, TCOz, Growth efficiency, Carbon conversion factor, Tri-laminate bags, Seawater culture
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 358349
URI: http://eprints.soton.ac.uk/id/eprint/358349
ISSN: 0948-3055
PURE UUID: 9fc5e2c1-2347-4b39-91da-e4e3b837f780

Catalogue record

Date deposited: 03 Oct 2013 16:00
Last modified: 08 Jan 2022 18:04

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Contributors

Author: Craig A. Carlson
Author: Nick R. Bates
Author: Hugh W. Ducklow
Author: Dennis A. Hansell

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