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The Quagga Mussel

Dreissena bugensis Andrusov 1897

 
Quagga Mussels (Dreissena bugensis) in Nevada, USA.
Photo: James N. Stuart (iNaturalist).
Contents

The Quagga Mussel is a freshwater mussel originated from the Black Sea region, which has spread out vehemently in recent decades as an invasive species throughout Europe and North America. It is closely related to the notorious Zebra Mussel (Dreissena polymorpha); however it is different from the latter by a more rounded shell shape and the absence of a pronounced keel.

MolluscaBase eds. (2025): Dreissena bugensis Andrusov, 1897.
Naturportal Südwest: Dreissena rostriformis bugensis (Andrusov, 1897): Quagga-Dreikantmuschel (In German).
Wikipedia: Quagga Mussel.

Description

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Quagga Mussel (Dreissena bugensis): Danube Island,
Vienna. Photo: Jasmin Rehrmbacher (iNaturalist).		  
The Quagga Mussel grows to a shell length of up to 32 mm. The shells are often striped in a light-dark pattern, which has contributed to the species' vernacular name, due to its similarity to the Quagga, a subspecies of African Zebra. The colouration, however, is variable, from almost white to dark brown. Like its relative, the Zebra Mussel, it attaches itself to the substrate with byssus threads, being especially particular to hard substrates like stone, rocks or boats, but also capable to settle sedimentary areas.

The planktonic larvae drift freely in the water, enabling a rapid distribution over rather far distances.

Origin and Distribution

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Quagga Mussel (Dreissena bugensis): Floridsdorf, Vienna.
Photo: Oliver Drescher (iNaturalist).
Originally, Dreissena bugensis was common in the estuary areas of the southern Bug River (hence the scientific species name bugensis), Dnepr and Inhulez in Ukraine. Since the 1940s, the species has begun spreading in Eastern Europe at first. During the 1990s it presumably reached North America in the ballast water tanks of ships, where it could establish itself massively, especially in the Great Lakes.

In Europe it has been documented in numerous countries since the 2010s, among them Germany, Austria, Bulgaria, France, Romania, Hungary and the Netherlands.

Presence in Europe

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Germany


Quagga Mussels (Dreissena bugensis): Neuchâtel, Switzer-
land. 		  
Photos: Nicolas Schwab (iNaturalist).		  
In Germany, the Quagga Mussel was first found in 2005. Since then, it has settled many flowing waters and canals, among them the Danube, Main and Rhine Rivers, as well as the Main-Danube-Canal, the Mittelland Canal and further water channels like the Dortmund-Ems-, Datteln-Hamm- or Rhine-Herne Canal. In 2016 it was also first detected in Lake Constance.

YouTube: BR quer: Umweltkatastrophe? Quagga-Muschel krempelt Bodensee um (In German).

Switzerland

In Switzerland, the Quagga Mussel first was proven to be present in the River Rhine near Basel in 2014 or 2015. Since then, it has been spreading continuously, even replacing the formerly introduced Zebra Mussel. Especially affected are the large lakes in the Alpine Foothills, such as the Lake Geneve, the Biel Lake, Neuenburg Lake, Murten Lake and since 2024 also the Zurich Lake. A main problem is the lack in regulations concerning the import of foreign boats. Albeit Switzerland is not a large country, there are no country-wide regulations to that effect, thus enabling the further spreading of the species.

Austria

 
Quagga Mussels (Dreissena bugensis).		  
Linz, Upper Austria.		  
Photos: Kaulquappe (iNaturalist).		  
In Austria, too, the Quagga Mussel in the meantime has become widespread. In Upper Austria it has, until now, been proven from different larger lakes and rivers:

Lakes:

Flowing Waters:

The first finding took place in the Attersee Lake and the Traun River in 2022, however genetic research has uncovered that the settlement could have taken place as early as since 2020. In June of 2023 an eDNA monitoring was undertaken in 23 lakes, which confirmed the findings that had so far been known. In further lakes such as the Wolfgangsee, Almsee, Hallstättersee, Gosausee or Irrsee, the species was proven genetically, but so far does not seem to have established itself durably.

Land Oberösterreich: Ausbreitung der gebietsfremden Quagga-Muschel in Oberösterreichs Seen verhindern (In German).

Consequences

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Quagga Mussels (Dreissena bugensis): Ossiach, Carinthia.
Photo: Irene Girandoli (iNaturalist).		  
The Quagga Mussel can inflict considerable ecological and technical damage:

Especially worrying is the ability of this species to spread out to settle deeper areas of water bodies. Studies in Lake Constance have shown that the species' biomass could increase to up to twenty times the current size until 2045. A similar timeline like in Lake Michigan (USA), where the species already makes 90% of the lake's entire biomass, are possible.

Great Lakes Now: Quadrillions of Mussels Are Invading the Great Lakes. ( YouTube Video).
Great Lakes Now: Invaders on the Menu. ( YouTube Video).

Distribution Prevention

To prevent a further spreading of the species, following preventive measures might be decisive:

Especially important is a federal or even European rulebook for the transfer of boats and equipment, a point that has, for example, proven problematic in Switzerland.

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Latest Change: 07.08.2026 (Robert Nordsieck).