• Ecosytem Invaders – Impact, Problems and Opportunities

    Invasive Species

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    Adorable troublemakers: Invasive species such as raccoons in Germany can upset the balance in a new ecosystem, especially when they don’t have any natural predators.

The world is getting smaller all the time, and one consequence of this phenomenon is that species are increasingly spreading to new regions and being introduced to new areas. These alien species can cause devastating problems, but while many invasive animals and plants have a negative impact on biodiversity and local economies, they can also be beneficial.

Story check

  • Challenge:
    Animal and plant species are sometimes introduced into new areas. Major problems can ensue if they then spread quickly and have no natural enemies.
  • Solution:
    Sometimes the new arrivals become part of the natural order. In isolated cases, mankind attempts to intervene in order to protect the existing ecosystem and domestic flora and fauna.
  • Benefits:
    Invasive species generally cause deep-rooted changes to ecosystems. But in isolated cases the invaders can also be beneficial to humans, for example as the source of a specific raw material.

Considered one of the most prominent types of invasive species, raccoons have been resident in Germany for 84 years now. Originally brought as pets from North America, around one million raccoons now live in Germany, where they are considered a menace: They threaten native bird species and are believed to be responsible for spreading diseases such as rabies.

New species like this can become a problem. Experts classify species as invasive when they breed and spread very quickly in a new habitat where there are no natural predators. This can cause an overabundant population, which ultimately out-competes native species. This phenomenon occurs in between 5 and 20 percent of all non-indigenous species. In the EU, 23 invasive animal species and 14 plant species are currently classified as species of union concern, which means they threaten biodiversity and necessitate control through international measures.

quagga mussel

Quagga mussels can clog pipes in waterworks and therefore cause economic damage.

Invasive species are often one of the factors responsible for declining biodiversity within ecosystems. Overall, they are the second most common cause of species extinction, and according to the International Union for Conservation of Nature (IUCN), they are the main cause of the disappearance of species in amphibians, reptiles and mammals.

76

The number of invasive species in Europe has increased by 76 percent since the 1970s.
Source: European Commission

These invaders not only harm an area‘s overall biodiversity, but they can also negatively impact the economy. One example is the quagga mussel, now widespread throughout the world, which overgrows water pipes, thus causing blockages and outages in waterworks. The EU member states alone spend a total of between EUR 9.6 and 12.7 billion per year on repairing damage caused by invasive species.

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Approximately 42 percent of threatened or endangered species are at risk due to invasive species.
Source: National Wildlife Federation

In rare cases, introduced species are beneficial

Regardless of whether animals or plants, large or small, one thing is certain: Invasive species affect ecosystems and humans across the globe. research has uncovered some interesting examples of the effects that alien species can have.

Invaders help material scientists

stalked sea squirt

American researchers have developed an unusual material by combining cellulose, a substance commonly used in paper production, with dried-up pieces of an invasive sea creature. The stalked sea squirt (Styela clava), a member of the tunicate family colonizes surfaces, by, for example, overgrowing harbor walls. The new material is flexible and durable, and could be used in food packaging, vehicle construction, biomedicine and building construction.

Ecosystems: Invasive species have a lasting effect

Japanese stiltgrass

Even after invasive species have vanished, they can still leave a mark. An example of this is Japanese stiltgrass. Even after this invasive grass species was eradicated in the eastern United States, U.S. researchers found that the ecosystem was unable to return to its original state, according to the findings of a three-year observation period.

A killer conquers a remote island

brown tree snake

An invasive snake species wiped out more than half of the native bird and lizard species on the island of Guam located in the western Pacific Ocean. The nocturnal brown tree snake was inadvertently brought to the island during the Second World War and rapidly proliferated. This also had an impact on mammals, with two out of three native bat species disappearing completely. Plant life was likewise devastated, as many of the ousted bird species had served the plants as seed carriers.

Green menace overgrowing bodies of water

Water hyacinth

Dense green mats of vegetation on the water surface make it almost impossible for ships to get through. Water hyacinth is a fast-growing, floating aquatic plant. Originally from South America, it is increasingly found in Africa, Asia, Oceania and North America. Fishermen suffer as a result, but also seafarers who are dependent on open waterways.

Giant worms from Asia spreading worldwide

hammerhead flatworm

At about half a meter long and with an appropriately shaped head, the hammerhead flatworm is hard to overlook. Nonetheless, this worm has been spreading largely unnoticed worldwide for decades and is regarded as an invasive alien. Ecologists in France and other areas are currently studying these Asian animals that pose a threat to native species such as earthworms. The method they are using to obtain new insights is referred to as citizen science, which is when members of the general public report on sightings and provide researchers with data. This has enabled researchers to examine the behavior of some hammerhead flatworm species in greater detail and to even describe a potentially new species.

Facts & Figures

  • Back in the 19th century, Charles Darwin, who decisively shaped our current knowledge of evolution, examined the extent to which new species were able to settle in unfamiliar areas.
  • There are over 12,000 non-indigenous species in Europe, of which 10 to 15 percent are invasive. These include mammals, amphibians, reptiles, fish, invertebrates and plants, as well as fungi, bacteria and other microorganisms.
  • Non-indigenous species can even alter an entire ecosystem, thus endangering native species. Nitrogen accumulates in the soil in the countryside where black locust trees (Robinia pseudoacacia) grow, which benefits plant species that thrive particularly well in these conditions.