Biological invasion

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The North American raccoon is a neozoa

As a biological invasion generally means the spread of an invasive caused by human kind in an area. According to the Federal Nature Conservation Act, based on EU Regulation No. 1143/2014 of the European Parliament and of the Council of October 22, 2014, this is defined as "an invasive alien species within the meaning of Article 3 No. 2" of this regulation. The benchmark is therefore not the national border, but the space of a natural community.

Ingo Kowarik calls the non-native organisms Neobiota ; a distinction is made between animals (neozoa), plants (neophytes) and fungi ( neomycetes ). Neobiota can, but need not be, invasive.

The concept of invasion itself must be viewed critically. An invasion (Latin invadere = to penetrate) describes the advance of military formations into foreign territory. They are at war and act accordingly. Since the First World War , the term has been associated with a large-scale and well-organized armed force.

To speak of a biological invasion is therefore imprecise, since it is neither a military and warlike action, nor is it intentional or organized on the part of humans. In addition, the term invasion has a decidedly negative meaning. Scientifically, however, the penetration of neobiotics cannot be assessed as positive or negative, but only described. In the assessment, cultural justifications then take effect as the results of the social negotiation processes.

The invasive species can change the ecosystem and displace native species. They can both increase and decrease the biodiversity of a habitat.

The decisive factor for the classification of such a process is the movement of the organisms into the new habitat by humans. The natural invasion of neobiota is not considered a biological invasion. However, that also depends on the perspective. From a purely ecological point of view, the reason for the shipment is irrelevant.

Biological invasions are the subject of research in invasion biology . This branch of biology developed from adventitious floristry . The British ecologist Charles Sutherland Elton is considered the founder of invasion biology with a publication in 1958.

General

Living things have migrated since species opened up new habitats. These natural migrations take place at a relatively slow pace and reach their limits where the species can no longer overcome natural expansion barriers such as water , mountains , ice , desert or the like on its own .

However, species can break through these natural boundaries under certain conditions. For example, an island can be reached and settled by means of driftwood , or the obstacle can be overcome using an appropriate host. Temporary land bridges, such as the Bering Strait , which made it possible to settle America in the last glacial period, are also important . Likewise, the formation of the Isthmus of Panama led to the so-called Great American Fauna Exchange and the disappearance of taxa such as the terror birds . These spreads take place without human influence.

With most natural migrations, the speed and quantity with which the species spreads in the new area is so slow that the resident species can adapt to the immigrants. If a resident species occupies the same ecological niche as the immigrant, then it is often possible to push back the immigrating species, or the original species can develop new habitats for its part.

Man-made shipments often have a completely different dimension. Its extent, range, speed and impact are significantly more extensive. The possibilities offered by modern shipping or air traffic are immense. The regularity with which a route is flown or driven, and thus the probability of exporting the same species to a certain location, is much higher than the probability with which, for example, representatives of the same species on a driftwood end up on the same island. Also incomparable is the quantity with which goods and people move today. In addition, the speed with which the often long distances are covered cannot be compared with that of a living being.

It is striking that there are very different definitions of the term biological invasion in the specialist literature . The numerous proposals differ mainly in the questions, 1) whether people have to be involved in the process of area expansion or whether natural, "independent" immigration is also an invasion and 2) whether a species is caused by the damage it causes in the new area , can be characterized as invasive or whether immigrant species that do not cause damage are invasive.

From a scientific point of view, a definition can look like this: Biological invasions are all man-made or natural processes of area expansion in which a barrier to spread has been overcome. A spreading barrier is understood to be an area which the species under consideration can only overcome with a probability approaching zero. The area in which the species gets after crossing the barrier was already ecologically suitable for it, but because of the barrier it was uninhabited for an evolutionary relevant time. It is therefore ecologically alien in this area. "

Invasive species are to be distinguished from alien species. An alien species is "... a wild animal or plant species if it does not occur in the wild in the area concerned or has not existed for more than 100 years;"

Transport routes

With advancing globalization and the acceleration of society, the ways in which an immigrant can reach a new living space have also changed. Due to globalization in particular, the routes from one place to another are being overcome ever faster and more frequently. Natural barriers such as water, mountains or deserts now play a much smaller role for invasive species.

In general, a distinction has to be made between an accidental shipment and the intended shipment.

Intended shipment

Biologically invasive species are often intentionally introduced as ornamental and useful plants. Most of the time, they are intended to benefit people directly or indirectly. This applies e.g. B. towards field crops such as the potato from South America or useful plants such as the tomato, which is also imported from South and Central America, which, however, cannot establish themselves in the field in our country.

Their ways of introduction are systematized in hemerochoria . It often happens that the plants grow wild and settle away from the gardens and agricultural areas. The same goes for animals.

One possible form of the intended shipment is e.g. B. the aquarium or terrarium . Initially kept in captivity, fish, reptiles or other animals are often released as soon as they get too big. Organisms for pest control are introduced, especially in horticulture, for example the Asian ladybird . This was brought to North America in 1916 and to Europe in 1982 to eat insects in greenhouses. Because it was released into the wild and is physically larger than most native ladybird species and has a high reproductive potential, it can displace other species.

Unintentional shipment

Unintentional shipments are much more common than intentional introductions. Organisms can reach new habitats around the world, especially with the transport of goods and people in the global economy . Invasive species can also be introduced into cargo aircraft. It is relatively easy to counteract the movement of larger animals. For this purpose z. B. the Washington Convention on Species Protection makes a contribution. In contrast, plants such as B. Narrow-leaved ragwort is often introduced as seeds, which is difficult to control due to its size.

The control and avoidance of small invertebrates , insects , polyps and protozoa as well as viruses is particularly difficult .

Organisms such as insects can be spread on or in plants. Invasive species are also repeatedly brought into contact with or in cut plants as well as fruit and vegetables . Sometimes they are also spread with plant products or plant and growing media.

Organisms can also be brought in with pets or farm animals. Many pets and farm animals carry pathogens on or in themselves, but are immune or vaccinated, which is why the diseases do not break out in them. In their new habitat they can primarily infect nearby unprotected species and U. trigger epidemics .

Invasive species can also be found in transport packaging.

Ballast water is one of the most important distribution routes for aquatic invasive species

Invasive species can also get into the means of transport themselves. Aircraft, for example, get from start to destination particularly quickly; this makes it easier for other organisms to survive. Ships can bring aquatic organisms into foreign waters in ballast water. Many small organisms survive in ballast water. Over 50,000 zooplanktic individuals and over 110 million phytoplanktic forms were found in one cubic meter . As a rule, only a few of the surviving organisms can survive permanently in the new waters, as most of them do not like the temperature, the food and the salinity of the water. Replacing the ballast water on the high seas is recommended as a countermeasure. The technology is not designed for a complete exchange. The Ballast Water Convention therefore provides that from 2017 at the latest, ballast water will be treated when it is taken into the ballast tanks and before it is released into the marine environment in order to render the organisms in them harmless. Some species of mussels were probably spread with sailboats (see below).

Temporal context

Invasive species have been with humans for a long time. In the past, however, the speed was much lower and the distances covered are no longer comparable.

Today, well understandable and momentous "biological invasions" took place especially with the discovery and settlement of America , Australia , New Zealand and several small islands. Their effects are still visible today. Artificially eradicating the invasive species is often impossible.

Conditions for "biological invasions"

Not every species that is moved can establish itself permanently or spread explosively. And in the positive case, it often takes years or even decades for a stable population to develop. In the absence of natural enemies or other factors (e.g. climatic) that can regulate the alien population, the invasive species can become a serious threat to habitat biodiversity .

In principle, the nature of the habitat and the climate must suit a species that has been moved . In addition, it needs suitable nutrition and several representatives are almost always necessary for a functioning population. That can be a few hundred or even thousands, but often only a few individuals of different sex are enough. However, it is not possible to make general statements about the species characteristics of neobiota that predestine them for a "biological invasion".

Another major threat to the native species are new pathogens that are brought in with the invasive species. Pathogens, fungi and parasites can be companions. An example is the noxious eel swim bladder worm, which originated in Japan, was brought to Europe and now affects European eels.

“Biological invasions” can cause all kinds of damage, both ecologically and economically.

In addition to the endangerment of biodiversity through displacement and extinction of native species, the ecosystem as a whole can also be affected: the loss of the extinct species often throws the ecological balance out of balance. This is often followed by a kind of chain reaction: other specialized species also suffer and die out. The situation is particularly serious when a key species disappears, on which a large part of the other species is directly or indirectly dependent.

Island ecosystems are particularly vulnerable

Islands are particularly vulnerable to invasive neobiota for two reasons. First, the species there are often tolerable to natural disturbances such as volcanism or floods, but less to anthropogenic influences in the course of slash and burn and pasture farming. Second, certain species are often not represented. These include predators, large herbivores, or rodents. If they penetrate, they can u. U. change the spectrum of species sustainably.

Damage to the economy

The Herkulesstaude is one of the problematic neophytes in Europe

The economic damage that invasive species can cause is not to be underestimated. However, they are difficult to calculate. They depend on the observed period and on the inclusion of the most varied of factors, which are often difficult to quantify (loss or gain of genetic diversity, costs of control, costs of illness for the victims, etc.).

In Germany, F. Reinhardt, M. Herle, F. Bastiansen and B. Streit calculated that twenty invasive species are said to have caused damage of 167 million euros annually. In fact, however, these are only approximate values ​​that are methodically weak. The authors of the study estimate - due to the lack of specific figures - from personal interviews with three foresters, for example, the "average problem area" for the late-blooming bird cherry in their forestry offices and then extrapolated this to the total German area, "... in which the late blooming bird cherry belongs to Time can be expected en masse. ”These are therefore very approximate estimates and empirical values ​​that are not well suited for a specific calculation.

The Herkulesstaude caused health treatment costs of estimated over one million euros annually in Germany. The chestnut leaf miner moth incurred costs of around 450,000 euros annually in the cities of Cologne, Frankfurt, Darmstadt, Munich and Berlin to remove the early fallen leaves from the infected trees for aesthetic reasons.

Case studies

Australia and New Zealand

The damage caused by invasive species is particularly striking in Australia and New Zealand: Originally there were hardly any predators there and the flora and fauna in other ways also differ greatly from that in Eurasia or America. The greatest predator in Australia was the thylacine , which was exterminated around 1900. The marsupials and many small mammals are only found in Australia and New Zealand. They were extremely endangered by the rabbits , rats , cats , dogs and foxes that were introduced and feral . Where there was no predator before, suddenly there were several predators and strong food competitors. Rabbits in particular reproduced explosively. This is also a danger for horses and riders, as the horses often step into the rabbits' burrows and can easily break a leg in the process, which usually leads to a fall and the death of the horse. There are around 1570 invasive species in New Zealand today, versus 1790 native species. In 2016, New Zealand's Prime Minister announced that he would launch a nationwide offensive to completely eradicate rats, weasels and possums on the island within the next 34 years.

The cane toad has been spreading across the continent from northeast Australia since 1936.

Chile and Argentina: change in flora

Most of the trade between Chile and Argentina is by road. The transport volume has more than tripled since 2000. Originally the Andes formed a natural barrier between the two countries, but this is increasingly disappearing due to increasing traffic. Of the 875 alien species, just under 300 occur only in Chile or Argentina and a good 300 in both countries. The UFZ researchers classified the yellow bartsia ( Parentucellia viscosa ), which was originally native to the Mediterranean, as the most dangerous for Argentina . Within 48 years it has spread to ten provinces of Chile. The Mediterranean blackberry (Rubus ulmifolius), the wine rose ( Rosa rubiginosa ) or the silver acacia ( Acacia dealbata ) have already established themselves in these countries. The striped gorse ( Cytisus striatus ), for example, has a good chance of containing the invasion , as it is not yet widespread.

Galapagos Islands

On the Galapagos Islands , wild goats and pigs compete for food for the slowly reproducing giant tortoises . Lonesome George lived on the Galápagos Island of Santa Cruz until June 24, 2012 as the last individual of one of the originally at least 15 and now only eleven giant tortoise subspecies.

Mediterranean Sea

After the Suez Canal was built , marine life migrated from the Red Sea to the Mediterranean , and to a lesser extent from the Mediterranean to the Red Sea. This process is called Lesseps migration (after Ferdinand de Lesseps , the builder of the Suez Canal).

Measures against invasive species

According to the IUCN's Species Survival Commission (SSC) , seven goals should be pursued:

  1. increase awareness that invasive species are a major threat
  2. Promote the prevention of the introduction of invasive species as a high-profile issue that needs national and international action to combat
  3. minimize unintended imports and prevent unauthorized imports of invasive species
  4. the assurance that intended imports of alien species, including for scientific purposes, will be carefully examined for their possible effects on biodiversity
  5. promoting programs and campaigns against invasive species and improving their effectiveness
  6. promoting national and international framework conditions for national laws and international cooperation to regulate the introduction of invasive species and to control them
  7. the promotion of necessary research and the development and publication of an adequate knowledge base to counteract the problem of invasive species

In 2000, the IUCN's Invasive Species Specialist Group (ISSG) published a list entitled 100 of the World's Worst Invasive Alien Species with 100 invasive species in island biotopes that were considered particularly problematic.

The European Union has issued Regulation (EU) No. 1143/2014 to regulate the handling of invasive species . The implementation in Germany takes place with the Federal Nature Conservation Act .

In Germany, invasive species are placed in different lists depending on their distribution and invasiveness:

  • invasive species
    • Warning list for invasive species not yet occurring in Germany (precautionary measures are in the foreground)
    • Action list for invasive species that so far only occur on a small scale in Germany (further spread should be prevented)
    • Management list for invasive species already occurring over a large area in Germany
  • potentially invasive species
    • Action list: (local) measures must already be justified despite the current lack of knowledge
    • Watchlist: Monitoring and research are in the foreground, further actions do not appear to be justified due to the low level of knowledge

See also

literature

Movie

  • The exotic ones are coming. Immigrated, introduced, naturalized. Documentary, Austria, 2008, 43 min., Script and director: Kurt Mündl , production: ORF2 , first broadcast: December 2nd, 2008, film information from ORF2.
  • Invasion of the exotic. Documentary, Germany, 2005, 43 min., Script and direction: Melanie Jost and Johannes Backes, production: Taglicht Media , ZDF , arte , series: Die Rache der Schöpf, first broadcast: November 14, 2005 on ZDF, summary by 3sat .

Web links

Individual evidence

  1. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe , p. 17.
  2. ↑ §7 Federal Nature Conservation Act (BNatSchG) , website laws on the Internet , Federal Ministry of Justice and Consumer Protection.
  3. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 21.
  4. ↑ K. Fuchs, H. Raab: dtv dictionary for history . Vol. 1. (AK), 7th edition, Munich 1990, p. 378.
  5. ↑ T. Heger: On the predictability of biological invasions . In: Neobiota , Vol. 4, 2004, p. 11.
  6. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 17.
  7. ↑ a b T. Heger: On the predictability of biological invasions . In: Neobiota , Vol. 4, 2004, p. 12.
  8. ^ Charles S. Elton: The ecology of invasions by animals and plants. Methuen, London 1958.
  9. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 11.
  10. ↑ T. Heger: On the predictability of biological invasions . In: Neobiota , Vol. 4, 2004, pp. 5-13.
  11. ↑ http :// Pflanzengesundheit.jki.bund.de/dokumente/upload/ee640_vo2014-1143_invasive_arten_de.pdf
  12. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 100.
  13. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , Pp. 359-361.
  14. ↑ nytimes.com: Downside of Being a Global Hub: Invasive Species , February 8, 2017.
  15. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 101.
  16. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 104.
  17. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 78.
  18. ↑ T. Heger: On the predictability of biological invasions. (Neobiota Vol. 4). Berlin 2004. pp. 45-46.
  19. ↑ On the multitude of favorable factors that must apply to plants alone in the phase of growth and reproduction, cf. T. Heger: On the predictability of biological invasions. In: Neobiota , Vol. 4, 2004, pp. 68-69.
  20. ↑ T. Heger: On the predictability of biological invasions . In: Neobiota , Vol. 4, Berlin 2004, pp. 136-137.
  21. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , P. 22.
  22. ↑ Ingo Kowarik: Biological Invasions. Neophytes and Neozoa in Central Europe. , Pp. 378-381.
  23. ↑ F. Reinhardt, M. Herle, F. Bastiansen: Economic consequences of the spread of Neobiota. Environmental research plan of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety Research Report 201 86 211, Berlin 2003, p. 151.
  24. ↑ F. Reinhardt, M. Herle, F. Bastiansen: Economic consequences of the spread of Neobiota. (Environmental research plan of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety) Research report 201 86 211, Berlin 2003, p. 48.
  25. ↑ F. Reinhardt, M. Herle, F. Bastiansen: Economic consequences of the spread of Neobiota . Environmental research plan of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety Research Report 201 86 211, Berlin 2003, p. 33.
  26. ↑ F. Reinhardt, M. Herle, F. Bastiansen: Economic consequences of the spread of Neobiota. Environmental research plan of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety Research Report 201 86 211, Berlin 2003, p. 232.
  27. ^ Peter Yeung: New Zealand announces plan to exterminate all rats . In: The Independent of June 25, 2016.
  28. ↑ Press release from the Helmholtz Center for Environmental Research: Chile is more dangerous for Argentina than the other way around . July 13, 2011, accessed January 29, 2012.
  29. ↑ Galapagos Giant Tortoise: George is dead . In: Spiegel Online , June 25, 2012, online , accessed January 19, 2014.
  30. ↑ Nature conservation assessments of invasiveness of alien species for Germany ( Memento from June 27, 2016 in the Internet Archive ) on neobiota.bfn.de
  31. ↑ BfN script 409 ( memento from March 26, 2016 in the Internet Archive ): Nature conservation-related invasiveness assessments for alien vertebrates living in the wild in Germany.