In contrast to related life forms such as certain species of snail, the zebra mussel develops indirectly. It hatches from an egg as a free-swimming larva that settles on the bottom and transforms into a clam.
Due to its high reproductive performance and this indirect life cycle via free-swimming larvae, the species can spread particularly well and quickly build up large populations.
In the 1990s, there were massive incursions in the native fish fauna in the Great Lakes of North America. The zebra mussels successfully filter the water and quickly remove most of the planktonic nutrifrom in ents the water, which can be seen as the reason for fish deaths.
The continuing intensification of worldwide shipping inevitably leads to the further spread of the zebra mussels. For example, in the North Sea (Germany), there are now more than 200 inversive species, most of which were introduced through shipping.
The invasion is not limited to specific regions but a global problem that now affects every country. In the long term, global homogenization will occur without effective countermeasures, which will also endanger regional ecosystems. Once invasive species have migrated, they are difficult to eradicate or control.
Effects of zebra mussels
The presence of zebra mussels in a body of water is usually associated with a multitude of ecological, recreational, and economic problems.
- Reduction in the density of phyto- and zooplankton, which are the basic foodstuffs for native organisms
- Shifts within the biodiversity and proportions of the animal and plant communities living in the water
- the water quality increases the clarity of the water -> increased growth of plants and algae
- can lead to widespread fish deaths
- can lead to biomagnification (accumulation of pollutants from the environment in living beings) and thus also to the accumulation of toxins in the food chain
Effects on leisure time:
- Beaches can be affected by the sharp mussels because people and animals can injure themselves on the shore or shallow water areas.
- The decomposition of mussels can lead to unpleasant odors
- Zebra mussels attached to boat hulls can increase drag and decrease speed, resulting in increased fuel consumption
- Zebra mussels clog engine intakes
- Zebra mussels can block raw water inlets such as drinking water and power generation.
- Damage to cooling water circuits in industrial systems, which lead to the malfunction of plate and tube bundle heat exchangers
So far, the main focus has been on research into the ecological consequences of invasive animals and plants. In a first global data analysis published in the journal “Science of the Total Environment,” 20 scientists from 13 countries compiled the economic costs specifically caused by aquatic invaders – that is, by water dwellers.
They conclude that these invasive aquatic species, which have established themselves in their new habitats, have cost at least 345 billion US dollars since the 1970s, such as damage to factories, power plants, water treatment plants, or catastrophic intrusions into commercial fishing.
The researchers criticize that less than a tenth of the amounts invested in repairing the damages would be spent on management measures such as preventing future invasions. They demand that more funds be invested in the management and prevention of invasions.