The invasive zebra mussel, originating from the Black and Caspian Seas, is rapidly spreading across Swedish lakes, posing a threat to native species. Authorities urge the public to prevent its spread by properly cleaning and drying water-related equipment.
Invasive Zebra Mussels Threaten Swedish Lakes: How to Prevent Their Spread
Invasive Zebra Mussels Threaten Swedish Lakes: How to Prevent Their Spread
The zebra mussel is one of the invasive species that both the County Administrative Board and the Swedish Agency for Marine and Water Management are warning about this summer. What many do not know is that the larvae spread between different lakes through wet swimwear, water toys, and boats.
The Swedish Agency for Marine and Water Management reports that the zebra mussel reproduces quickly.
Originally from the Black Sea and Caspian Sea, the mussel has spread to Sweden through human activity.
The first discovery was made in Lake Mälaren in 1926, and now the zebra mussel is found in Mälaren, Hjälmaren, Roxen, and Glan, as well as smaller lakes in Uppland and Södermanland. They have also spread further to both the Saxtorp Lakes in Skåne and Lake Storsjön in Östersund.
"Once they arrive, they cannot be eradicated. You can't just remove them," says Lina Tomasson from the Swedish Agency for Marine and Water Management to SVT.
Harmful to Lakes
What makes the zebra mussel harmful to other aquatic plants is that its rapid reproduction risks eradicating native species in the lakes. This occurs through increased competition for nutrients in the lake and space to grow.
"They become mass occurrences. They grow on top of other mussels, preventing them from getting food, and on plants, blocking their light," Tomasson tells the channel.
According to the Global Invasive Species Database, they are considered one of the world's 100 most invasive species.
Agency's Call to Action: How to Prevent the Spread
The Swedish Agency for Marine and Water Management now urges everyone swimming in lakes where the zebra mussel is present to be diligent in emptying all water from boats and buckets, washing boats, boots, and other equipment, and drying swimwear, life jackets, and fishing gear.
This is because zebra mussels need moisture to survive.
Once they have spread, they are almost impossible to eradicate—the only successful example is in the Saxtorp Lakes in Kävlinge, where chemicals were used, a method not preferred in natural lakes.