ARKHANGELSK, February 6. /TASS/. Specialists of the Laverov Federal Research Center for the Arctic Integrated Studies (the Russian Academy of Sciences, Arkhangelsk) assessed the prospects for freshwater pearl mussel populations in Russia's northeast in different climatic scenarios until 2100, the Center's expert in ecology and biogeography Ilya Vikhrev told TASS, adding the assessment was done for the protection of rare mollusks.

"We have forecasted the population structure changes dynamics under two climate change scenarios - moderate and extreme. The study's aim was to evaluate the European pearl mollusk's genetic diversity in its range's northeastern part: the Murmansk, Karelia, Arkhangelsk and Leningrad Regions. The assessment is necessary to understand the populations' conditions," he said.

Biologists calculated what would happen to pearl mussels when the average annual temperature increased by 2.3 degrees and by 5 degrees by 2100 against the current time. In the tests, the scientists used microsatellites - sections of the nuclear genome. The method is used to track recent genome changes: from 50 to 500 years. "Earlier results have demonstrated that an increase in the average annual temperatures leads to the population depression," the expert noted.

Interestingly, pearl mussels live also in southern regions, like, for example, in Portugal, though there they are smaller and live three times less. During the study, scientists found the genetic diversity was the highest in the Kola Peninsula populations, it was lower in the Baltic Sea rivers populations; and as for pearl mussels in Central Karelia - the mussels were very different there, which possibly is due to the anthropogenic impact, for example, when artificial dams disrupt the exchange between neighboring populations.

"Having forecasted genetic clusters in the future, we saw the genetic diversity is decreasing. The predominant cluster becomes the one that is conventionally called the "northern" cluster" - it is widespread on the Kola Peninsula and in the White Sea Region's southern part. It will become dominant, including in Karelia, and will displace the specific "Karelian" cluster," the scientist said. "At the same time, the Baltic Sea populations, which belong mainly to the "southern" cluster, maintain their isolation and even grow, becoming more isolated from other populations. They actually become the carrier of a unique genetic component that will disappear in almost all other populations."

Populations to be protected

In the assessment, the experts have identified three areas where first of all the pearl mussel requires protection. The Kola Peninsula populations make the greatest contribution to Russia's genetic diversity of the species, and those populations are in a depressed state, where already now exists a threat of their loss.

"The third protection object is the Baltic Sea populations," he added. "Results of the earlier modeling for the extreme scenario have demonstrated that suitable habitats for the mussels will remain only on the Kola Peninsula and in Karelia's north, while the Baltic Sea basin falls into the red zone. These populations quite possibly will be under the strongest pressure due to climate change, though at the same time they carry a unique genetic component that will not remain anywhere else." Here, artificial reproduction is a possible conservation option.