A population of marble crayfish has been discovered in the Stiemerbeek Valley in Genk (Limburg), and that is not good news. The marble crayfish is an American crayfish and an invasive species that causes a lot of damage to the ponds and streams where it occurs.
Last summer, at the request of the Institute for Nature and Forest Research (INBO), volunteers searched ponds and streams all across Flanders for crayfish. In Limburg, 25 volunteers took part. A population of marble crayfish was found at one location, which is not good news.
The INBO’s Wietse Chanet explains: ‘The marble crayfish is an American crayfish, an invasive species that causes a lot of damage in the ponds and streams where it occurs. The non-native crayfish eat anything that fits into their mouths. They can eat aquatic plants and aquatic animals. They will empty the whole pond.’
Self-cloning crayfish
The marble crayfish is also a very special crayfish, Mr Chanet continues. ‘The marble crayfish originated in aquariums. It evolved from another American crayfish that then developed into a self-cloning crayfish becoming the marble crayfish.’
Because the crayfish is able to clone itself, its numbers increase rapidly. They can also move from one pond to another or to another stream. They can also burrow into the soil for while. It is a tough species!
Released or escaped
So how did this alien species end up in the Stiemerbeek, a stream in Limburg? ‘They either escaped or were released from aquariums,’ the researcher explains.
Because the species reproduces so quickly, scientists need to intervene as soon as possible when it is spotted anywhere. ‘Catching the crayfish is one possibility when the population is still small. We are also looking into whether native predatory fish eat the non-native crayfish.’
Besides Limburg, marble crayfish have already been found elsewhere, mainly in Antwerp province.