Lake Vouglans in Haut-Jura is now wintering, and its level is low enough to observe the shores. Thanks to this phenomenon, we can see at the end of November, an invasive mollusk that we have not seen for a year in the Jura, and which is basically destroying the lake's ecosystem.
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The invasive species of zebra mussels is once again out in Haut-Jura. A retired canoe enthusiast, Gilles Lacroix had the opportunity to observe them during one of his trips on Lake Vouglans on Monday November 18, the body of water having dropped significantly following its wintering. Vouglans is 35 kilometers long, it is the third artificial lake in France.
While walking with his partner on the body of water located at an altitude of 450 meters, Gilles Lacroix was eager to discover new things, but he would have preferred not to find this species of mussels in his playground, “It saddens me, we know where it comes from. The boats brought back the mussels and contaminated the lake”.
Already a whistleblower in 2022, Gilles Lacroix once again shares a video of the location of zebra mussels. “We are far from the carpets of mussels that we saw two years ago. Today it is more localized towards Moirans-en-Montagne, on the Refraiche cove”explains the canoe enthusiast.
The small zebra mussel clings to all hard surfaces, trees, rocks, stumps. It would have arrived from the Black Sea, via the Danube canals, then from the Rhine transported by boats.
Although its population has been declining for two years in Vouglans, finding an area where zebra mussels congregate is far from good news. These are at the heart of a problem directly linked to the ecosystem of Lake Vouglans. The alvins (young fish) are hampered in their feeding, and fish in their reproduction. Mussels deplete the environment.
The zebra mussel is an invasive species present in Lake Vouglans. By 2022, large quantities of them had been found around the lake during the winter.
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© Laurent Brocard – France Télévisions
As the technical manager of the Jura fishing federation, Mehdi El Bettah, tells us, “the difference this year is that the water went lower than last year, the situation is normal”. Zebra mussels are found deeper in lakes, and Vouglans is no exception.
ALSO READ: VIDEO. Far from the sea, an invasive mussel has colonized Lake Vouglans in the Jura
He also explains to us that the drop in the water level kills the molluscs that are not submerged, but others still remain in the body of water and proliferate. The decline in zebra mussel numbers therefore remains only temporary, “it's good that their population is going down, but the remaining individuals will reproduce again”.
