Conopeum chesapeakensis, a new invasive bryozoan species, was found for the first time in the Baltic Sea and in Europe off the coast of Finland. The species is native to the Atlantic estuaries of North America and has so far not been found as an invasive alien species on other continents. The species, which inhabits brackish waters, has spread across the salty ocean with shipping traffic. The bryozoans form dense, branching growths up to five centimetres long, which are very similar in appearance to the native bladderwrack. However, on close inspection, the surface structure of the growth is composed of small calcareous cells, like that of its close relative, Einhornia crustulenta, which forms dense stands in the Baltic Sea. Each individual animal lives in a cell sheltered by filtering food from the water.

The occurrence in the Bothnian Sea was discovered in the seawater intake channels of the Olkiluoto power plant, where a new type of detached growth was observed in December 2023. The species was identified by DNA tagging at the Finnish Museum of Natural History and was also confirmed by microscopic tagging in an August sample from the Finnish Environment Institute's harbor invasive species monitoring in Porvoo's Kilpilahti Bay. The finding of the species in two different marine areas suggests a wider distribution. It is possible that the new bryozoan species will continue to spread in the Baltic Sea, where the low salinity is more in line with the species' habitat requirements.

A species card will be created for the species on the vieraslajit.fi website.

Photo of the article: Teollisuuden voima