Will the microbial filter prevent methane emissions from Baltic Sea coasts in a warmer future?

Anaerobic oxidation of methane via sulphate reduction is the main microbial process preventing the seafloor release of large quantities of CH4 from sediment to the water column and potentially the atmosphere. This process, also known as the microbial filter, is controlled by temperature and sulphate concentration in seawater.

Climate change will affect the efficiency of this filter by reducing the sulphate concentration and increasing temperature of Baltic Sea waters. The precise effects are still, however, poorly understood.

A failure of the microbial filter will potentially be associated with widespread methane release along Baltic Sea coasts amplifying trends in anoxia and climate change.

Here we plan to study the changes in methane production and consumption via sulphate reduction in the sediments and water column of a bay in the Baltic Sea that has been heated (ca. 5-10°C) by the discharge of the cooling waters of a powerplant for 50-years. We will compare data from this bay (an analogue for the future warmer Baltic Sea) with an adjacent, unaffected bay.

We will test the impact of long (50-years) and short (seasonal, daily) term changes in temperature in the formation and consumption of methane and the efficiency of the microbial filter, in addition to changes in microbial communities and metabolic pathways during methanogenesis. Our robust communication plan will assure that results of this project will be effectively transfer to the society.