The Carpet Sea Squirt Spreading Rapidly in Swedish Water

13 Nov, 2025

Christopher Andersen and his diving buddies at Strömstad’s sports diving club have found loads of the invasive sea squirt, also called ‘sea spit,’ in parts of the Koster Sea at the Swedish West coast, where they did surveys for the species just a year ago.

Anna Dimming, coordinator for aquatic invasive species at the County Administrative Board of Västra Götaland, is concerned. The budget allocation has been reduced by 80 per cent, and they are now virtually powerless in the fight against the dreaded sea squirt species, which can cause great damage to the ecosystem.

Deep Sea Reporter has been to Kosterhavet National Park and witnessed the devastation.

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