Duck mussel habitat spreads from Syria to Arctic, Russian scientists say

"We have been 'hunting' different duck mussel species to understand their relations," the scientist said. "But we have found they were just one widely spread species, which lives in most different nature zones - from deserted Syrian rivers to Yakutia's basins, which freeze up in minus 50 (degrees). It's an unexpected discovery."

The center's biologists have studied the mollusk populations' bio-geography and genetic features. They have organized a few dozen expeditions, including to remote areas of Siberia and the Urals, to the basin of the Orontes River (Nahr al-Asi), which runs across Lebanon, Syria and Turkey, and to other regions of Eurasia that have local mussel populations. They also used international databases. "The studies' final part focused on populations inhabiting Arctic rivers. We have collected samples in the basins of the Northern Dvina, Pechora, Taz, Ob, Yenisei and Lena Rivers, and conducted genetic analyses," the center's expert in molecular ecology and bio-geography Artyom Lyubas said.

Relatives that look nothing alike

The scientists had identified four genetic groups and one subgroup, but they all turned out to be one species, although quite often mollusks in different parts of Eurasia look nothing alike. In Yakutia's lakes, duck mussels have flat green shells, while samples from Buryatia at the border with Mongolia have very big massive shells. The mussels in the Orontes River have yellow shells.

"They are convex, shiny, like a peach or an apple. We were sure that was a different species," the center's director told TASS. "But it turned out that was a slightly isolated genetic line of the same duck mussel that lives in Siberia, in the Arctic, in Russia's European part. The thing is - in the Middle Eastern basin conditions it has acquired those different morphology features."

Once the scientists agreed that was just one species, they could for the first time analyze the specific genetic variability of one species within an entire continent. They are able to track how the mussels have settled there. Duck mussel's larvae parasitize on fish that eventually carry the mollusks.

"We have observed very interesting moments where the Black Sea basin genetic group is very widespread in Siberia, up to the Lena River basin, which proves in the past those basins used to be connected. We also can see how into the Lena basin has settled a number of fish species, such as roach, pike, burbot and others," he continued.

Duck mussel plays an important ecological role in reservoirs. The mussels filter water, and their shells accumulate various substances, including toxic substances and those contained in small amounts of emissions carried by the current. Thus, duck mussels are sensitive bio indicators that point to changes in ecosystems.

The researchers plan to decode fully the duck mussel genome. They want to find out what genetic features ensure the mussel viability and its adaptability to such different climate conditions, the scientist said. "When one species lives in desert rivers, where it is plus 50 (degrees), and also in freezing rivers, where the temperature in winter may fall to minus 50 degrees - this is fantastic, of course," he added.

The project was implemented with the financial support of the Russian Ministry of Science and Higher Education and the Russian Science Foundation. At the next stage, the group studying duck mussels wants to analyze how they accumulate heavy metals and other toxic elements and compounds.