Why the invasive quagga mussel could change Swiss lakes forever

The quagga mussel, a non-edible species native to the Black Sea region, is rapidly spreading across Swiss lakes, raising concerns among experts about its potential to disrupt local ecosystems.

First identified in Switzerland in 2014 in the River Rhine near Basel, the quagga mussel (Dreissena bugensis) has since colonized several major lakes, including Lake Constance, Lake Geneva, Lake Neuchâtel, Lake Biel, Lake Murten, and Lake Hongrin, as reported by the Swiss Federal Institute of Aquatic Science and Technology (EAWAG).

Alongside the zebra mussel, which has been proliferating in Swiss waters since the 1960s, the quagga mussel is among the most aggressive invasive species. Its ability to reproduce year-round and thrive in soft substrates of deep-water zones gives it a competitive edge, allowing it to outcompete zebra mussels and dominate deep-water habitats.

How it spreads – and what it might do

Quagga mussels can spread naturally, by floating downstream in their larval form, or via human activities. They can hitch a ride in the ballast, bilge, or engine-cooling water of boats and other watercraft. 

Additionally, adult mussels adhere strongly to boats and equipment, facilitating their spread if surfaces are not properly cleaned or dried before being moved to different bodies of water.

EAWAG researcher Piet Spaak, who leads the SeeWandel project - a collaborative research initiative involving institutions from Germany, Austria, and Switzerland - has expressed concerns about the broader ecological implications of quagga mussel proliferation. 

Drawing on experiences from North America, Spaak warns that the presence of this invasive species could significantly upset the delicate balance of lake ecosystems. While the exact consequences remain uncertain, potential impacts may have wide-ranging effects on local habitats. 

Quagga mussels filter large amounts of phytoplankton, which could lead to a reduction in plankton populations. In turn, these changes in plankton availability may affect fish populations and overall aquatic biodiversity.

Furthermore, mussel shells accumulating along shorelines could result in higher maintenance expenses for boats, pipes, and fishing gear.

As the spread of quagga mussels continues, ongoing research and monitoring efforts will be crucial to understand and mitigate their impact on Swiss lake ecosystems.

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