UN Biodiversity Conference: How Invasive Species Threaten Diversity

Status: 12/12/2022 3:09 p.m

With globalization, many animal and plant species are conquering new habitats. Some of these invasive species can cause massive ecological and economic problems.

By Simon Bartoschek, SWR

It is only about four centimeters tall and has an inconspicuous grey-black pattern. And yet life on and in Lake Constance whirls it upside down: swimmers injure their feet on their sharp edges. Underwater residents suffer from their competition. And it costs the water suppliers millions of euros. The Quagga Shell.

Originally native to the Black Sea region, it was first detected in Lake Constance in 2016, probably brought in by pleasure craft. Since then, the invasive species has multiplied explosively, with serious consequences: “Lake Constance will not be destroyed. But it will no longer be the same lake,” says Silvan Rossbacher from the Swiss water research institute Eawag im SWR.

Invasive species – drivers of species extinction

The quagga mussel invasion shows it: Animal or plant invaders can upset ecosystems and endanger native species in the process. Of the World Biodiversity Council (IPBES) even describes the “invasion of alien species” as one of five “direct drivers” of the global extinction of species.

However, not all newly immigrated plants (neophytes) or animals (neozoa) are generally problematic. “Most of the non-native species that have been able to settle here do not pose any threats to our nature or health,” he said Federal Agency for Nature Conservation (BfN). But about ten percent, according to the BfN, “prepare nature conservation problems”.

What are invasive species?

Species that occur naturally with us are referred to as native or indigenous species. Alien species have come to us through human influence, either intentionally (e.g. as a crop) or unintentionally (e.g. as “stowaways” in ships’ ballast water).

The year of the discovery of America, 1492, serves as a chronological delimitation. All species that came to us after that are called neobiota. Since then, around 930 neobiota species have become established in Germany alone, including many useful plants such as potatoes, corn and tomatoes. In addition, there are currently almost 2000 non-native animal, plant and fungal species that are considered to be “unstable”, with a high number of unreported cases being assumed.

displacement of native species

For example, when they, like the calico crab, completely eat up the eggs of the amphibians living there in ponds, like one SWR report indicates. Or when, like the immigrant muskrat, they decimate the native river mussel. Or if, like the raccoon, they are carriers of pathogens.

Invasive species can also change entire ecosystems. Where today, for example, the quagga mussel covers the bottom of Lake Constance in large numbers, other highly specialized species that depend on uncovered rocky or sandy bottoms are left behind: their habitat is lost.

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Economic damage in the billions

However, the proliferation of the quagga shell also devours money. For example, because the use of Lake Constance water as drinking water is becoming more complex. “The larvae of the quagga mussels swim into the pipes and settle as mussels on and in the extraction pipes and conveyor systems,” according to the association “Bodensee Wasserversorgung”. This necessitates regular cleaning work and investments of millions in filter systems.

And this is just one of countless examples of how the spread of an invasive species has economic consequences. According to a recent Study by the Senckenberg Nature Research Society Since 1960, the global consequential damage caused by invasive species, including crop losses and burdens on the health system, has totaled almost one trillion euros.

Combat almost impossible

So the problem is well known – and yet it is getting bigger and bigger. Mainly due to the worldwide flow of goods, which enables plants and animals to advance into ever new regions as “stowaways”. “The rate at which new invasive species are being introduced appears to be higher than ever and shows no signs of slowing down,” according to the 2019 IPBES report. And climate change is likely to exacerbate the problem, because it is doing it warmth-loving species easier to expand their habitat.

Which invasive species are the most problematic?

A list of the “Invasive Species Specialist Group” (ISSG) of the “International Union for Conservation of Nature” (IUCN) contains100 of the World’s Worst Invasive Alien Species“, including the Chinese mitten crab or the Asian tiger mosquito.

The European Union maintains a list (“union list“) with currently 88 invasive animal and plant species for which certain minimum standards apply for prevention, early detection and monitoring, among other things, including Egyptian goose, raccoon dog or Himalayan balsam. Critics say that the list only contains a fraction of the invasive species that are problematic in Europe .

But the ability to keep invasive species in check once they have spread is limited. Prevention and, if necessary, immediate measures at a very early stage – more is hardly feasible. “Many problematic neobiota species that are established over a wide area will no longer be eradicated,” says the BfN. Fighting should be done “only in justified individual cases” in order to “keep a species under control or eliminate it locally”.

Can no longer be eradicated – this probably also applies to the small, inconspicuous grey-black patterned mussel in Lake Constance: “If we are lucky enough with the quagga mussels”, says the head of the Institute for Lake Research Langenargen in SWR, “it will change somewhere on a level off at a certain level. But we definitely won’t be able to get rid of them.”

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