ARKHANGELSK, November 29. /TASS/. Specialists of the Laverov Federal Research Center for the Arctic Integrated Studies (the Russian Academy of Sciences) discovered a new population of freshwater pearl mussel in the Arkhangelsk Region, the center's press service told TASS.
"A previously unknown population of the European pearl mussel, a freshwater mollusk listed in Russia's Red Data Book and in the regional lists of endangered fauna species, was found in the Kushereka River that runs across the Onega District in the Arkhangelsk Region," the press service said. "The Laverov Federal Research Center for the Arctic Integrated Studies' specialists found the population during an expedition in 2024."
A scientific group studying freshwater mollusks explored the Kushereka's local areas, where they had found individual pearl mussels. Geographically, the Kushereka is in the district's western part near the border with Karelia. The river that is about 78 km long originates in the Shapochka Mountain and flows into the White Sea.
Previously, historical and scientific sources have not mentioned the Kushereka as a reservoir with pearl mussels. According to scientists, until recently, the Arkhangelsk Region had twelve rivers and streams inhabited by the European pearl mussel (Margaritifera margaritifera). The Kushereka became the 13th reservoir on that list.
Historical sources refer to data on the extraction of river pearls, which became one of the reasons for the mussel population depletion. Among other negative factors scientists eye global warming, leading to a reduction in the mussel's life cycle as it prefers cold and clean rivers and streams with fast currents, and the sunken wood that releases toxic substances harmful to freshwater fauna.
"Quite often the pearl mussel distribution in the reservoir is not very clear. For example, we have examined the upper, shallow part of a neighboring river in the Onega District, where we expected to find a population of mollusks, but we could not find anything. At the same time, the middle course turned out to be populated. The mussels' distribution may be associated with the presence in local areas of host fish with mollusk larvae (glochidia) that feed on biological material on the gills before the maturation phase. This also may be due to a certain type of soil, and due to consequences of timber rafting," the press service quoted the center's Director Ivan Bolotov as saying.
Environmental indicator
The presence of the freshwater pearl mussel in the Kushereka may indicate the reservoir's fairly good ecological condition: M. margaritifera belongs to the indicator species that react sharply to environmental changes. The species is a natural biological filter that supports water purity in reservoirs.