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New Discoveries of Marbled Crayfish Cause Concern in Northern Europe

SWEDEN – New specimens of the suspected marbled crayfish have once again been discovered in Sweden, this time nearly 300 kilometers southwest from where the species was first discovered last November. The marbled crayfish is considered invasive in many European countries including Sweden.

The marbled crayfish is a tropical crustacean that originated in Florida and Georgia, USA. With the help of humans, it has spread to other countries such as Germany, Austria, the Netherlands, England, and Italy. Photo by Thorbjörn Hongslo/National Veterinary Institute.

“We are looking very seriously at the details, especially considering that the findings were made in an area with nearby water systems having a high biological value,” says Erland Lettevall, analyst for environmental monitoring at the Swedish Agency for Marine and Water Management.

The discovery was made in early July during an inventory of wetlands biodiversity. Several marbled crayfish, both adults and young specimens, were found in one location alone.

“Genetic identification is not yet complete, but based upon appearance, they can hardly be mistaken as anything other than marbled crayfish,” says Lennart Edsman from the Department of Aquatic Resources at the Swedish University of Agricultural Sciences.

The species reproduces through parthenogenesis, a form of asexual reproduction in which fertilization is not needed for creating offspring. “It can outcompete native species, and it multiplies very quickly and has a very high survival rate,” explains Lettevall.

“The species can carry infectious diseases such as the crayfish plague and others that don’t exist in our waters. It’s a serious threat to biodiversity.”

Published: 2013-12-03

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