Respiration rates of marine prokaryotes and implications for the in vivo INT method

Seguro, Isabel, Vikström, Kevin, Todd, Jonathan D., Giovannoni, Stephen J., García-Martín, E. Elena, Utting, Robert and Robinson, Carol (2025) Respiration rates of marine prokaryotes and implications for the in vivo INT method. Biogeosciences, 22 (21). pp. 6225-6242. ISSN 1726-4189

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Abstract

The balance between the uptake of CO2 by phytoplankton photosynthesis and the production of CO2 from prokaryo-, zoo- and phytoplankton respiration controls how much carbon can be stored in the ocean and hence how much remains in the atmosphere to affect climate. Yet, despite its crucial role, knowledge on the respiration of plankton groups is severely limited because traditional methods cannot differentiate the respiration of constituent groups within the plankton community. The reduction of the iodonitrotetrazolium salt (INT) to formazan, which when converted to oxygen consumption (O2C) using an appropriate conversion equation, provides a proxy for both total and size fractionated plankton respiration. However, the method has not been thoroughly tested with prokaryoplankton. Here we present respiration rates, as O2C and formazan formation (INTR), for a wide range of relevant marine prokaryoplankton including the gammaproteobacteria Halomonas venusta, the alphaproteobacteria Ruegeria pomeroyi and Candidatus Pelagibacter ubique (SAR11), the actinobacteria Agrococcus lahaulensis, and the cyanobacteria Synechococcus marinus and Prochlorococcus marinus. All species imported and reduced INT, but the relationship between the rate of O2C and INTR was not constant between oligotrophs and copiotrophs. The range of measured O2C/INTR conversion equations equates to an up to 40-fold difference in derived O2C. These results suggest that when using the INT method in natural waters, a constant O2C/INTR relationship cannot be assumed, but must be determined for each plankton community studied.

Item Type:	Article
Additional Information:	Data availability. Respiration rates and cell abundances are available for download at BODC; https://doi.org/10.5285/2be8f599-592c-5de2-e063-7086abc02acd (Seguro et al., 2025). Funding information: This study was funded by the UK Natural Environment Research Council (NERC) project “REMineralisation of organic carbon by marine bActerIoplanktoN (REMAIN) – reducing the known unknown” (grant no. NE/R000956/1) and The Leverhulme Trust project “Marine bacterioplankton respiration: a critical unknown in global carbon budgets” (grant no. RPG2017-089) awarded to Carol Robinson. During the writing of this manuscript Isabel Seguro was funded by the UK NERC project “The abiotic and biotic factors determining microbial respiration, a key process in ocean carbon storage (MicroRESPIRE)” (grant no. NE/X008630/1) awarded to Carol Robinson as part of the BioCARBON strategic research programme
Uncontrolled Keywords:	sdg 14 - life below water,sdg 13 - climate action ,/dk/atira/pure/sustainabledevelopmentgoals/life_below_water
Faculty \ School:	Faculty of Science > School of Environmental Sciences Faculty of Science > School of Biological Sciences Faculty of Science University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups:	Faculty of Science > Research Groups > Wolfson Centre for Advanced Environmental Microbiology Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation Faculty of Science > Research Groups > Environmental Biology Faculty of Science > Research Groups > Collaborative Centre for Sustainable Use of the Seas Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Depositing User:	LivePure Connector
Date Deposited:	30 Oct 2025 15:31
Last Modified:	31 Oct 2025 09:31
URI:	https://ueaeprints.uea.ac.uk/id/eprint/100861
DOI:	10.5194/egusphere-2025-3009

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