Evaluating Climate Gas Balances in Marine Environments Using Mesocosm Experimental Facilities

Marine environments play a critical role in regulating greenhouse gas (GHG) fluxes, particularly CO₂, CH₄, and NO_x, which influence global climate processes. This is becoming more apparent where some ecosystems are now being shown to be net carbon sources rather than previously thought sinks. However, studying these fluxes in situ is challenging due to the dynamic nature of marine systems. Mesocosm experiments provide a controlled, and when large enough, realistic approach to isolate and investigate the effects of climate change variables on marine gas fluxes, enabling precise assessments and bridging the gap between laboratory and field studies.

Highly precise and controllable 5m deep replicated (n = 12) mesocosm experimental facilities at Umeå Marine Sciences Centre in Sweden help determine GHG uptake and fluxes in coastal and open-ocean systems whilst also focusing on individual or combined impacts of key climate change drivers – including temperature rise, acidification, freshening, nutrient input and critical for gas exchange, ice cover. Gas exchange rates can be measured over multiple months using high-resolution gas analysers and custom-built mesocosms to mimic natural light and nutrient gradients in a variety of settings from full saline to freshwater conditions. Comparative analyses can be made between control and climate-altered scenarios to isolate specific drivers of gas flux changes.

The use of mesocosms proves essential in dissecting the complex responses of marine GHG fluxes to climate drivers, providing insights difficult to attain only from field-only studies. This research approach reinforces the value of mesocosm facilities in forecasting climate-related changes in marine gas balances and offers a methodological blueprint for future marine climate studies.

 

Keywords:

Mesocosm, climate gas flux, greenhouse gases, climate change, CO₂, CH₄, NO_x, ecosystem response