If average annual temperatures rise by 2.3 degrees Celsius and 5 degrees Celsius by 2100, the pearl mussels' genomes will be in danger, Russian biologists say.
Scientists at the Federal Research Centre for Integrated Arctic Studies of the Ural Branch of the Russian Academy of Sciences in Arkhangelsk have assessed the prospects of pearl mussel populations in the north-east of Russia under different climatic scenarios until 2100.
"We predicted the dynamics of population structure changes in the future under two climate change scenarios, temperate and extreme. The objective of the study was to assess the genetic diversity of the European pearl mussel in the north-eastern part of its range: the Murmansk region, the Republic of Karelia, the Arkhangelsk and Leningrad regions. This assessment is needed to understand the state of the populations," said Ilya Vikhrev, a leading researcher at the Laboratory of Molecular Ecology and Biogeography.
The scientists used microsatellites—sections of the nuclear genome—to analyse them. This technique allows them to track what changes in the genome have occurred over recent timescales: from 50 to 500 years.
It has been shown before that an increase in mean annual temperature leads to population suppression.
Pearl mussels also live in southern regions of the world, but they are smaller than the northern ones and live three times less. In the course of the research, the scientists found that the Kola Peninsula populations have the highest genetic diversity. The populations of the Baltic Sea rivers have lower genetic diversity, and there is a mottled picture among the pearl mussels of central Karelia, possibly due to anthropogenic impact and water dams disrupting the genetic exchange.
"We saw that genetic diversity is decreasing. The cluster that is conditionally called 'northern', which is widespread on the Kola Peninsula and in the southern part of the White Sea region, is becoming predominant. It will become dominant, including in Karelia, and will displace the specific 'Karelian' cluster. At the same time, the Baltic Sea populations, which belong mainly to the 'southern' cluster, retain their isolation and even increase it, becoming more isolated from other populations. And they actually become a carrier of a unique genetic component, which will disappear in almost all other populations," said Vikhrev.
The assessment allowed scientists to identify three areas where the pearl mussel is primarily in need of protection. According to the scientists, the Kola Peninsula populations make the greatest contribution to the genetic diversity of the species in Russia. The populations in Karelia are in an oppressed state, and there is already a threat of their loss. The third unit of protection is the Baltic Sea populations.
Modelling in an extreme scenario showed that suitable habitats for pearl mussels would remain only on the Kola Peninsula and in northern Karelia, while the Baltic Sea basin falls into the red zone. It is quite possible that these populations will be under the most severe pressure from climate change. At the same time, they carry a unique genetic component that will not remain anywhere else.
Artificial reproduction is named as a possible conservation option.
Source: TASS
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