Will ocean acidification cause a large-scale loss of habitat-forming brown seaweeds?

Brown seaweeds are the largest and most complex group of marine macroalgae.

They form underwater forests that are biodiversity hotspots and they provide ecosystem services with immense ecological and societal value.

In comparison to seagrass meadows, the anthropogenic pressure and threats to seaweed-based coastal habitats are less studied. Ocean acidification (OA) has to date been assumed to have little or even positive effects on brown seaweeds.

Our recent results indicate that this may be a hasty conclusion, as we could see that a OA-exposed seaweed became drastically more vulnerable to both grazing and physical forces.

Building on these pioneering findings, the current project aims at testing if increased vulnerability is a general response to OA in habitat-forming brown seaweeds along and the Swedish west-coast and what consequences this could have in an ecological context.

Another part of the project will, in collaboration with commercial seaweed farmers, experimentally test what the OA-effects will mean for sea-based cultivations of kelps.

The results of the project will form a better knowledge base for future predictions, monitoring and management of habitat-forming brown seaweeds.

It will also provide the emerging seaweed cultivation industry in Sweden with knowledge that enables them to adapt their future strategies in a situation where the seawater is continuously becoming more acidic.