Acidification in the Baltic Sea is increasing – but other environmental problems may have larger effects on the ecosystem

A survey published by The Biological Impacts of Ocean Acidification (Bioacid) shows that the increasing acidity of the world’s oceans is likely to have a harmful effect on all marine species. But the impacts on the ecosystem are very complex and other environmental problems – fertilizers, overfishing and coastal development – may also play a key role. More research is needed to access the effects of how these problems interact with climate change and acidification.

In the fall of 2017 a survey was published by The Biological Impacts of Ocean Acidification (Bioacid). It is considered to be the most complex report on the impacts of ocean acidification published so far. Studies were done in both laboratory environments and conducted in oceans around the globe, including the Baltic Sea, North Sea, Arctic and Papua New Guinea.

Carbon dioxide (CO2) emissions from modern society are making the oceans more acidic. Ocean acidification is caused by carbon dioxide (CO2) – originating from the combustion of fossil fuels – dissolving in seawater and leading to the production of carbonic acid, which in turn leads to a reduction of the pH of the water. The eight-year study, which involved more than 250 scientists, finds that juveniles are especially at risk of being harmed, and that ocean acidification can potentially affect food security and limit the capacity of the oceans absorbing CO2 from human emissions.

Although scenario modeling suggests that acidification in the Baltic Sea may increase 3-fold by 2100, the effects on the ecosystem are poorly understood and other environmental problems have larger effects on the ecosystem. Available data suggests that most species in the food web can cope with expected changes in pH. Some, such as eelgrass (Zostera marina) may benefit directly from these changes. However, they can still be adversely affected by indirect changes in the food webs – and other species, including bivalves and crustaceans may be directly harmed.

The Baltic Sea is affected by increased temperatures resulting from global warming, excess fertilizers from agriculture leading to eutrophication, overfishing, pollution and coastal development. Those factors are negatively affecting habitats and biodiversity. More research is needed using multiple stressors and/or multiple trophic levels to access the effects of how these problems interact with climate change and acidification.

As always, knowledge is the key to change, and the Baltic Sea Future congress is a part of the path to a better future. Together we can make a change for the better, so join us in Stockholm!