Researchers from Stockholm University collecting intact parts of the Baltic Sea floor for investigations of greenhouse gases. The instrument is called "boxcorer". Photo: Alessandra Vicenzi.
Researchers from Stockholm University collecting intact parts of the Baltic Sea floor for investigations of greenhouse gases. The instrument is called "boxcorer". Photo: Alessandra Vicenzi.

Baltic clams and worms release as much greenhouse gas as 20 000 dairy cows 
Worms and clams enhance the release of methane up to eight times more compared to sea bottoms without animals, shows a study by scientists at Stockholm University and Cardiff University.

While greenhouse gas emissions are increasing to unprecedented levels, the source and sink mechanisms for these emissions are still not yet fully understood. Sea bottoms have been shown to be important contributors of the two strong greenhouse gases methane and nitrous oxide. Although a large part of this emissions are consumed in the water column, in shallow coastal ecosystems an important fraction is released to the atmosphere, where they contribute to global warming.

A study conducted by scientists from Stockholm University and Cardiff University suggests that worms and clams enhance the release of methane up to eight times more compared to sea bottoms without animals.

"It sounds funny but small animals in the seafloor may act like cows in a stable, both groups being important contributors of methane, due to the bacteria in their gut", says Dr. Stefano Bonaglia, the lead author of the study and post doc researcher at the Department of Ecology, Environment and Plant Sciences at Stockholm University.

"Our estimates show that 10 percent of the total methane emission from the Baltic Sea may be due to clams and worms, which is equivalent to the methane produced by about 20,000 dairy cows or, in other words, 7 percent of the Swedish dairy cow population. These small yet very abundant animals may play an important, but so far neglected, role in regulating the emissions of greenhouse gases in the sea", he concludes.

"Our findings greatly improve our understanding of how greenhouse gases fluxes are regulated in marine coastal ecosystems and  are relevant for the debate on these habitats should be managed in the context of multiple pressures resulting from human activities", says Stefano Bonaglia.

Read the article in Scientific Reports, www.nature.com/articles/s41598-017-13263-w