The impact of climate change stressors on microbial respiration and community structure: ocean acidification and artificial upwellling

Abstract

Microbial community respiration significantly influences the ocean’s capacity to sequester CO2 in marine ecosystems. Despite its pivotal role, there remains limited understanding of the variability and magnitude of community respiration in marine ecosystems, especially regarding its sensitivity to climate change stressors. This knowledge gap hinders a comprehensive grasp of its contribution to the global carbon cycle. Traditional in situ approaches for measuring community respiration are subject to several methodological limitations, particularly that of sensitivity in oligotrophic ecosystems, which cover more than 40% of the Earth's ocean surface. These limitations thus contribute significantly to the uncertainty in global estimates of carbon budgets. To address these challenges, enzymatic techniques such as ETSvitro offer a fast and sensitive method to assess respiratory activity rates at spatial scales that are difficult to cover using conventional approaches. The method involves reducing the tetrazolium salt, INT, within the respiratory chain under substrate saturation levels (i.e., NADH, NADPH, and succinate). However, the reliability of the ETSvitro method has been questioned because it measures potential respiratory activity rather than actual respiration. In response to these concerns, another enzymatic technique, ETSvivo, emerged presumably as a more realistic estimate of actual respiration [...]