Environment | Endangered mussels like “frosted with milk chocolate” – a pair of pictures shows the destruction

Calmed down crossing the mussels’ home river with heavy machinery can cause large-scale destruction to the river’s mussel population.

The reason is that the turbulent flow of the river spoils the waterway from the crossing to the downstream. The difference between the upper and lower flow is visible.

The forest machine was repeatedly driven across the shallow river to Stora Enso’s logging site in Suomussalmi. The destruction was revealed last week, and now rescue work is urgently being done on the river to try to contain the damage.

Driving with heavy machinery has, however, stirred up a lot of sand, mud and logging residues. Mussels in their spiracles are revealed under the material, explained Metsähallitus’ project manager Pirkko-Liisa Luhta on site on Wednesday.

After going hundreds of meters downstream, the mussels are covered in steam, Huhta says. In the upper reaches, the bottom is still gravelly and suitable for river pearl mussels.

Police investigates the case as a serious nature conservation crime.

For the river pearl mussel, i.e. raw, it is destructive in itself that it is run over with a heavy machine. The species is pacified, and it must not be disturbed even by picking it up without a special permit.

However, what is worse for the entire mussel population is that the turbulence makes the downstream unviable. Räakku requires a clean base where it can move and burrow.

“It is above all important for its children, the little ones,” explains Luhta.

Small clams spend their first years of life in bottom gravel. Therefore, water and oxygen must flow there. When that can’t happen now, the little critters will die. The old ones may spread over time, but new ones will not be born in the dirty bottom.

“Then it will be out of the habitat of the brutes.”

Also the old brutes are now in trouble in the area. They don’t react like healthy individuals, says Luhta.

“Räakku is kind of brown and rough. About 400 meters away, the rocks are as if they were covered with milk chocolate, when they are covered with sand,” he describes.

“Their feet are completely brown because the insides are full of sand.”

They have the same body functions as humans, Luhta reminds. It is dangerous if a lot of substances that do not belong in the body enter the body.

Some of the brutes raised from the bottom are clearly already dead. Others are now being lifted upstream to safety.

On Tuesday and Wednesday, the renovators had carried more than 3,000 pieces of rubble from a distance of less than 50 meters in Suomussalmi’s Hukkajoki, Luhta said.

Hukkajoki’s stock, which is now in trouble, has been doing quite well until now. The fact that the rescuers have also found young clams in the mud is a sign of that.

Mussel is much longer than humans. It can live to be over 200 years old and is Finland’s longest-lived animal species.

Raakus live in clean flowing waters, which they themselves also keep clean. A single river pearl mussel filters 50 liters of water per day while extracting food from the water. At the bottom of the stream, there can be thousands of clams.

However, mussels cannot withstand such a huge load.

In Finland, most of the river pearl mussels’ habitats have become unsuitable for them. Only a hundred or so occurrences are known, although in the past there have been strains in streams all over the country.

Nowadays, there are mainly raakus in the north. Only eight raw streams are known from the south of Oulu, and in many places the population is running out.

“Rippiäit”, sums up Luhta.

When the wildebeests disappear, many other species also leave. They consider their environment suitable for many others and in general can only live in waters that are also needed by many other species of stream waters.

Mussel was pacified already in 1955, but it is still highly endangered.

At the beginning of their life, the larvae cling to the gills of salmon or trout, but in the 20th century, rivers have been dammed so that the fish cannot migrate. At the same time, after the wars, the swamp was drained into forest land, which changed the waterways.

In addition, rivers have been churned up to facilitate fishing and clams have been opened in the hope of pearls. Trolling and pearl fishing have been abandoned, but the lack of fish and forestry in particular still threaten the krauts.

Most of Finland’s river pearl mussels live outside protected areas, Luhta says.

In the conservation program drawn up a few years ago, it is recommended that, in order to save raw material, logging should not be done right next to the stream.