Zebra mussel

Zebra mussel ( Dreissena polymorpha )

The zebra mussel ( Dreissena polymorpha ), also known as the zebra mussel, is one of the representatives of the Autolamellibranchiata, a subclass of the class of mussels ( Bivalvia ).

Appearance

The zebra mussel is distinguished by the characteristic triangular, boat- like shape. It reaches a length 26-40 mm and a width of 17 - 20mm. The shells are dark brown to black, broken by light brown stripes.

The zebra mussel is one of the few freshwater mussels, which pass through a free-swimming larval stage.

Origin

The earliest documented evidence of the zebra mussel in Europe date back to the Miocene ( 2-11 million years ago). Until the 18th century the population increased steadily in Europe. Thereafter, it began by shipping a re- immigration, coming from the Black Sea, up the Danube one. The mussels attach themselves to boat hulls or arrive as larvae in ballast water of ships in the new habitat. Since then occurred several colonization waves with numbers of individuals of up to 100,000 animals per square meter. Because of the worldwide ship transport zebra mussels spread increasingly since the 1980s in the Great Lakes of North America from. Through its strong filter effect, the Secchi depth has doubled in Lake Erie.

Problem

The zebra mussel is a very strong competitive nature, which attaches itself to water plants and mussels. This leads to a proliferation and disruption of the natural biodiversity of ecosystems. Accordingly, it is an invasive form of invasive species. Ducks and waterfowl, especially carp, however, benefit from this new source of food.

In addition, taking damage in cooling water systems due to fouling in pipes and heat exchangers greatly. Such contamination can, however, prevent reliable with powerful filters. In addition, it is known that potassium chloride toxic effect on the shell without any risk of similar adverse effect on other aquatic species known to date.

Bioindicators

Zebra mussels are used as bio-indicators for the freshwater ecosystem. They are particularly suitable, inter alia, as bio-indicators because they

• Are common,
• A wide ecological valence and
• Have a sedentary lifestyle,
• Are all dissolved and suspended in water constituents in close contact and
• Record directly from the water pollutants.

Therefore, they are collected for years by the Environmental Specimen Bank, archived and analyzed for various environmental substances. This allows, for example, examined changes in methyl mercury contents and conclusions on environmental quality are drawn.