ARKHANGELSK, April 17. /TASS Correspondent Irina Skalina/. Biologists of the Federal Research Center for Integrated Arctic Studies (the Russian Academy of Sciences' Urals Branch) worked in an international team to find that the giant Chinese pond mussel (bivalve mollusks) Sinanodonta, which are spreading aggressively in the world's reservoirs, contains three different species, the Center's Director Ivan Bolotov told TASS, adding this information is important to control the invaders.

"This group of mollusks is the giant Chinese pond mussel. It has always been very complicated for taxonomy studies as it lacks morphological features to distinguish the species. It has taken ten years and a huge amount of genetic information around the world. Thanks to this, we have managed to review them and to break them into three species: Sinanodonta Woodiana, Sinanodonta Lauta and Sinanodonta Pacifica, and to show that Pacifica settles in the tropics, while in the temperate latitudes live Woodiana and Lauta. This is fundamentally important in terms of controlling biological invasions, since the Chinese pond mussel is the most aggressive group that spreads very actively," the expert said.

The scientists have determined for the first time that Sinanodonta Pacifica is an invasive species coming from the island of Taiwan. It has reached the continent from fish farms - with fish like tilapia and bighead carp. It has spread already to Malaysia, Myanmar, the Philippines and the islands of Indonesia, as well as to New Guinea, Iraq, Costa Rica, and the United States.

The Woodiana originates from the Yangtze River, and the Lauta originates from the Amur tributary, the Sungari River. In 2020, Arkhangelsk experts proved the Chinese pond mussels had settled actively in large Russian reservoirs. In the Volga River, they are forming dense settlements, in the Yenisei and the Ob they live in waters heated by thermal power plants. The mussels have been found in the Moscow Region already.

Synodonts have large shells. They can reach 26 cm in diameter. These mussels are much bigger than local species, and they develop dense settlements and push out local mollusks and insects. Additionally, the invaders' larvae parasitize on fish. "The environmental risk lies in the fact that fish, infected with Synanodont larvae, become immune to the larvae of local mollusk species - it begins to reject them," the scientist said. In this situation, native species are decreasing.

The mussels can displace the local fauna, and also they can damage infrastructure facilities by forming large settlements. The Chinese pond mussels are very unpretentious. For example, Woodiana can live in abandoned ponds and in pits with non-flowing water. What it needs is to have fish there.

Control

The rapid and global spread requires control to prevent further invasion, the expert continued. "Right now, they already have almost global spread, and thus they require special biology control measures, special actions from politicians, for example, to control legally the settlement of fish from farms," he explained.

Biologists insist fish planting material must be checked for the presence of parasites, and imported aquaculture must undergo quarantine. Additionally, the pond mussels must not be available in pet stores.

There are no effective methods to combat these mollusks, and the population may be destroyed only in small non-flowing reservoirs. In 2010, the mussels were found at fish farms in New Jersey. Specialists there chose to lower water in all ponds, and killed fish with a toxic substance. The international group of researchers recommends removing manually the Chinese pond mussel from reservoirs.

However, the mussels may be useful. For example, in some regions they are edible. Besides, they are filters that can improve water quality.