They're impossible to miss! They are everywhere, encrusting the rocks, carpeting the muddy lake bottoms and inexorably invading European lakes. There are thousands of them per square metre. They are 𝗹𝗲𝘀 𝗠𝗼𝘂𝗹𝗲𝘀 𝗾𝘂𝗮𝗴𝗴𝗮.
The vernacular name Dreissena bugensis comes from 𝗱𝘂 𝗻𝗼𝗺 𝗱 𝘂𝗻 𝘇𝗲̀𝗯𝗿𝗲 𝗻𝗼𝗺𝗺𝗲́ 𝗤𝘂𝗮𝗴𝗴𝗮 𝗼𝘂 𝗖𝗼𝘂𝗮𝗴𝗴𝗮, striped only on the neck and front of the body. As on the Quagga, the mussel's stripes disappear on its ventral side.
Polymorphic, at maturity it measures 𝟮𝟬 𝗺𝗺 𝘀𝘂𝗿 𝗺𝗮𝘅𝗶𝗺𝘂𝗺 𝟰 𝗰𝗺. It is equipped with cilia that allow it to suck water (one to several litres per day) into its cavity using an "inhalation siphon" and thus extract food particles (phytoplankton, zooplankton, bacteria, and even their own larvae).
The Quagga Mussel 𝘃𝗶𝘁 𝟯 𝗮̀ 𝟱 𝗮𝗻𝘀 is found in the fresh and temperate waters of lakes, rivers and canals, but does not like well-oxygenated waters with strong currents, where it has difficulty attaching itself to the substrate.
Unisexual, externally pollinated, very efficient, 𝗲𝗹𝗹𝗲 𝗮 𝗹𝗮 𝗰𝗮𝗽𝗮𝗰𝗶𝘁𝗲́ 𝗱𝗲 𝗽𝗿𝗼𝗹𝗶𝗳𝗲́𝗿𝗲𝗿 𝗺𝗮𝘀𝘀𝗶𝘃𝗲𝗺𝗲𝗻𝘁 𝗲𝘁 𝗿𝗮𝗽𝗶𝗱𝗲𝗺𝗲𝗻t despite mortality among veliger larvae (the larval stage of molluscs that has a ciliated veil enabling it to move through the water) of up to 99%.
In addition, like its congeners, it has 𝗹𝗮 𝗳𝗮𝗰𝘂𝗹𝘁𝗲́ 𝗱𝗲 "𝗳𝗮𝗰̧𝗼𝗻𝗻𝗲𝗿" 𝗹𝗲 𝗽𝗮𝘆𝘀𝗮𝗴𝗲 𝗲𝘁 𝗹𝗮 𝗾𝘂𝗮𝗹𝗶𝘁𝗲́ 𝗱𝗲 𝘀𝗼𝗻 𝗲𝗻𝘃𝗶𝗿𝗼𝗻𝗻𝗲𝗺𝗲𝗻𝘁 through the excretion of pseudofaeces, organic matter that is deposited and whose composition has the power to attract or repel other organisms (hence its so-called "engineering" role).
𝗟𝗮 𝗤𝘂𝗮𝗴𝗴𝗮 𝗽𝗿𝗲́𝘀𝗲𝗻𝘁𝗲 𝗲𝗻𝗳𝗶𝗻 𝘂𝗻𝗲 𝘁𝗼𝗹𝗲́𝗿𝗮𝗻𝗰𝗲 𝗽𝗮𝗿𝘁𝗶𝗰𝘂𝗹𝗶𝗲̀𝗿𝗲𝗺𝗲𝗻𝘁 𝗲́𝗹𝗲𝘃𝗲́𝗲 𝘃𝗶𝘀-𝗮̀-𝘃𝗶𝘀 𝗱𝗲𝘀 𝘃𝗮𝗿𝗶𝗮𝘁𝗶𝗼𝗻𝘀 𝗱𝗲 𝗰𝗼𝗻𝗱𝗶𝘁𝗶𝗼𝗻𝘀 𝗱𝘂 𝗺𝗶𝗹𝗶𝗲𝘂 such as temperature, acidity, turbidity and anoxia (lack of oxygen). It is also highly resistant to biocidal substances because it has effective detoxification means and the ability to shut down in an environment that is toxic to it.
Add to this its phenomenal vitality and the unwitting complicity of humans, and it's easy to see why it has been able to expand its range so effectively. The Swiss Confederation warns: 𝗣𝗮𝗿 𝘀𝗼𝗻 𝗱𝗲́𝘃𝗲𝗹𝗼𝗽𝗽𝗲𝗺𝗲𝗻𝘁 𝗲𝗻𝘃𝗮𝗵𝗶𝘀𝘀𝗮𝗻𝘁, 𝗹𝗮 𝗠𝗼𝘂𝗹𝗲 𝗾𝘂𝗮𝗴𝗴𝗮 𝗽𝗼𝘂𝗿𝗿𝗮𝗶𝘁 𝗲𝗻𝗴𝗲𝗻𝗱𝗿𝗲𝗿 𝗱𝗲𝘀 𝗰𝗼𝘂̂𝘁𝘀 𝗲́𝗰𝗼𝗻𝗼𝗺𝗶𝗾𝘂𝗲𝘀 𝗲𝘁 𝗲́𝗰𝗼𝗹𝗼𝗴𝗶𝗾𝘂𝗲𝘀 𝗰𝗼𝗻𝘀𝗶𝗱𝗲́𝗿𝗮𝗯𝗹𝗲𝘀 !
Source of information : Lémaniques n°113
Photo credit: Nicolas Marechal, 1793 & Moules Quagga
