EU network of mesocosms facilities for research on marine and freshwater ecosystems open for global collaboration.

Task 7.3

Task 7.1 Development of mobilized planktonic mesocosms

Task 7.2 Emerging automated, high-frequency imaging techniques for breakthroughs in aquatic food web research in mesocosms

Task 7.3 Applying GHG flux measurements to benthic/pelagic and pelagic mesocosms

Applying GHG flux measurements to benthic/pelagic and pelagic mesocosms

Partners: Lead AU, co- lead UU, Contributors: LMU, CNRS-MARBEC, SYKE, UH, MET

Duration: Month 1-36

Experimental testing of the role of aquatic systems in greenhouse gas (GHG) emissions and carbon uptake is critical to understand the driving mechanisms of gas fluxes between aquatic systems and the atmosphere. CO2 dynamics vary over short time scales (hourly, diurnally) and CH4 emissions in shallow waters are dominated by bubble release (ebullition), which is episodic in nature and therefore highly discrete in space and time. In order to address this, we will explore the potential for developing near-continuous measurements in mesocosm-scale experiments using low cost, low energy demanding sensors for CO2 (infra-red sensors) and CH4 (a solid state, semi-conductor system). Low-cost solutions to data storage and remote data transfer will be developed in collaboration with 7.1.2.

To develop an autonomous system capable of near continuous measurement of GHGs in mesocosm experiments, we will construct and test chambers capable of self-flushing or venting. The sensors and chambers will be combined in a stand-alone unit capable of measuring GHG fluxes several times over a diurnal cycle, at a cost low enough to allow their routine use in multiple mesocosm experiments. The units will be tested at several locations in combination with other established methods of GHG analysis within the consortium. There will in addition be a joint test/harmonisation workshop (AU, UU, UH and SYKE).

Finally, as aquatic GHG emissions are especially relevant in shallow waters, both fresh, estuarine and marine, it is critical to include benthic processes and sediments in the system. Therefore, task 7.3 will build on the work in 7.1.1 to adapt the raft and mesocosm system for use in shallow waters including sediments, development and testing benthic mesocosms for use in soft sediments.