What are invasive neobiota?
Neobiota are organisms that have not been living in a certain area before and only got there through human influence. Thea are therefore non-native (or alien) with regard to that area. Neobiota can be animals (neozoa), plants (neophyta) but also micro-organisms such as fungi or bacteria. Some of these non-native species have undesirable effects on native species, habitats or ecosystem functions. In this case, they are called invasive.
Since the beginning, species are spreading from area to area: by migration or passive transport, e.g. with water or wind. Are the environmental conditions in the newfound habitat all right, they are able to colonize and to reproduce. As an example, Europe often was (re-)colonised by new or returning species after the ice ages.
Did you know ...
edelweiss originally is from Central Asia? After the last ice age (about 10.000 before), it colonized the European Alps?
Leontopodium alpinum © S. Worischka
Due to anthropogenic effects, these kind of migrations are strongly accelerated. Some animal or plant species are spread intentionally as ornamental or production species, or unintentionally (e.g. with ships or as seeds). Many species travelled from their area of origin to distant continents this way.
Quiz #1
Where do these alien species (in Central Europe) come from?
Egyptian goose
(Alopochen aegyptiacus)North Africa
Round goby
(Neogobius melanostomus)Black Sea and Caspian Sea basins
Killer shrimp
(Dikerogammarus villosus)Black Sea and Caspian Sea basins
Muskrat
(Ondatra zibethicus)North America
Mandarin duck
(Aix galericulata)East Asia
Black bullhead catfish
(Ameiurus melas)North and South America
Asian clam
(Corbicula fluminea)Asia, Africa and Australia
Raccoon
(Procyon lotor)North America
Policeman's helmet
(Impatiens glandulifera)Asia / western Himalayas
Species that were introduced in ancient times, are referred to as archaeobiota while more recently introduced species are referred to as neobiota. There are different definitions of this so-called “recent times” but in Germany the crucial year to officially differentiate between archaeo- and neobiota is 1492.
Quiz #2
Which of these species are Neobiota in Central Europe, which are ArchaeobiotaP
Spinycheek crayfish (Faxonius limosus)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Rainbow trout (Oncorhynchus mykiss)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Zebra mussel (Dreissena polymorpha)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Policeman’s helmet (Impatiens glandulifera)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Common grape vine (Vitis vinifera)

Native species
Wrong
Archaeobiota
Right
Neobiota
Wrong
Corn poppy/ red poppy (Papaver rhoeas)

Native species
Wrong
Archaeobiota
Right
Neobiota
Wrong
Potato (Solanum tuberosum)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Tomato (Solanum lycopersicum)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Wheat (Triticum sp.)

Native species
Wrong
Archaeobiota
Right
Neobiota
Wrong
Round goby (Neogobius melanostomus)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Pumpkinseed (Lepomis gibbosus)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
Chinese mitten crab (Eriocheir sinensis)

Native species
Wrong
Archaeobiota
Wrong
Neobiota
Right
European bullhead (Cottus gobio)

Native species
Right
Archaeobiota
Wrong
Neobiota
Wrong
Brown trout (Salmo trutta fario)

Native species
Right
Archaeobiota
Wrong
Neobiota
Wrong
Stone crayfish (Austropotamobius torrentium)

Native species
Right
Archaeobiota
Wrong
Neobiota
Wrong
Common carp (Cyprinus carpio)

Native species
Wrong
Archaeobiota
Right
Neobiota
Wrong
Roman snail (Helix pomatia)

Native species
Wrong
Archaeobiota
Right
Neobiota
Wrong
Touch-me-not balsam (Impatiens noli-tangere)

Native species
Right
Archaeobiota
Wrong
Neobiota
Wrong
European rabbit (Oryctolagus cuniculus)

Native species
Wrong
Archaeobiota
Right
Neobiota
Wrong
Common or smooth newt (Triturus vulgaris)

Native species
Right
Archaeobiota
Wrong
Neobiota
Wrong
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Question x / y
Some neobiota are unobtrusive. These species are part of flora and fauna without causing damage, like the freshwater jellyfish Craspedacusta sowerbyii, the mandarin duck (Aix galericulata) or the potato (Solanum tuberosum).
But other neobiota are able to spread really wide and fast, endanger native species, transport new deseases, can change whole ecosystems or cause economic damage. These species are called invasive neobiota. Most of them were introduced more or less recently during industrialization or globalization to new regions, river catchment areas or continents. This process of transportation as well as the establishment of invasive species is called biological invasion.
Examples of invasive species in Germany and the Czech Republic are

Round goby, (Neogobius melanostomus) © S. Worischka

Egyptian goose (Alopochen aegyptiacus) © S. Worischka

Spinycheek crayfish (Faxonius limosus) © P. Kozak

Asian knotweed (Fallopia japonica) © S. Worischka

Policeman’ s helmet (Impatiens glandulifera) © S. Worischka
Neobiota in European rivers
Humans use rivers and streams in many different ways – and often quite intensively. Channels between formerly separate river catchment areas, international shipping as well as global trade are promoting the introduction of invasive aquatic species, e.g. fish, mussels and small crustaceans from the Ponto-Caspian region or American crayfish species.
There are various transport pathways:
- as „stowaway” in or on boats and ships (ballast water, biofouling/ growing on ship hulls and screws),
- as fishing bait,
- release of exotic aquarium pets,
- intentionally stocking (in order of economic benefits),
- carrying of eggs, (e.g. by birds),
- upstream by active migration or downstream by drift,
- active migration over land
Quiz #3
By which transport types were these species (most probably) introduced?

Spinycheek crayfish (Faxonius limosus)
“stowaway”: in the ballast water of ships
True
Wrong! Correct is: deliberately introduced / disseminated to compensate the declined populations of noble crayfish
False
This answer is wrong!

Zebra mussel (Dreissena polymorpha)
“stowaway”: in the ballast water of ships/ attached to ships
True
This answer is right!
False
This answer is wrong

Brook trout (Salvelinus fontinalis)
introduced as ornamental fish
True
Wrong! Correct is: introduced as edible fish
False
This answer is wrong!

Coypu (Myocastor coypus)
Introduced for fur production
True
This answer is right!
False
This answer is wrong!

Japanese knotweed (Fallopia japonica)
introduced as ornamental and crop plant
True
This answer is right!
False
This answer is wrong!

Stone moroko/ topmouth gudgeon (Pseudorasbora parva)
introduced as edible fish
True
Wrong! Correct is: “stowaway”: unintentionally, when introducing grass carp
False
This answer is right!

Signal crayfish (Pacifastacus leniusculus)
deliberately introduced / disseminated to compensate the declined populations of noble crayfish
True
This answer is right!
False
This answer is wrong!

Colorado potato beetle (Leptinotarsa decemlineata)
introduced for pest control
True
Wrong! Correct is: “stowaway”: unintentionally, when introducing potato plants
False
This answer is right!

Grass carp (Ctenopharyngodon idella)
introduced as ornamental fish
True
False! Correct is: introduced as pest plant control
False
This answer is right!

Common carp (Cyprinus carpio)
introduced for pest control
True
Wrong! Correct is: introduced as edible fish in the Middle ages
False
This answer is right!

Argentinian waterweed (Egeria densa)
“stowaway”: introduced with ballast water and attached to ship engines
True
Wrong! Correct is: introduced as ornamental plant
Trifft nicht zu
Die Antwort ist richtig!

Chinese mitten crab (Eriocheir sinensis)
deliberately introduced as food crayfish
True
Wrong! Correct is: “stowaway”: in the ballast water of ships
False
This answer is right!

Roman snail (Helix pomatia)
introduced by the ancient Romans as food snail
True
This answer is right!
False
This answer is wrong!

Policeman’s helmet (Impatiens glandulifera)
seeds stuck to the feet of migratory birds
True
Wrong! Correct is: introduced as ornamental plant
False
This answer is wrong!

Round goby (Neogobius melanostomus)
“stowaway: in the ballast water of ships
True
This answer is right!
False
This answer is wrong!

Killer shrimp (Dikerogammarus villosus)
“stowaway: in the ballast water of ships
True
This answer is right!
False
This answer is wrong!

Rainbow trout (Oncorhynchus mykiss)
introduced as edible fish
True
This answer is right!
False
This answer is wrong!

Mandarin duck (Aix galericulata)
introduced as ornamental birds
True
This answer is right!
False
This answer is wrong!

Pumpkinseed (Lepomis gibbosus)
“stowaway”: Eggs stuck to the feet of migratory birds
True
Wrong! Correct is: introduced as ornamental fish
False
This answer is wrong!
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Question x / y
Dispersal rates of invertebrate invasive neozoa in European water ways (km/ year), 3-6 records per species
Species | dispersal rate (km/ year) Average | dispersal rate (km/ year) Maximum |
---|---|---|
Asian clam (Corbicula fluminea) | 63 | 276 |
Zebra mussel (Dreissena polymorpha) | 65 | 199 |
Caspian mud shrimp (Chelicorophium curvispinum) | 44 | 137 |
Killer shrimp (Dikerogammarus villosus) | 112 | 461 |
Pontic waterlouse (Jaera sarsi) | 109 | 185 |
- Asian clam (Corbicula fluminea)
- dispersal rate (km/ year)
ø 63
max 276 - Zebra mussel (Dreissena polymorpha)
- dispersal rate (km/ year)
ø 65
max 199 - Caspian mud shrimp (Chelicorophium curvispinum)
- dispersal rate (km/ year)
ø 44
max 137 - Killer shrimp (Dikerogammarus villosus)
- dispersal rate (km/ year)
ø 112
max 461 - Pontic waterlouse (Jaera sarsi)
- dispersal rate (km/ year)
ø 109
max 185
Modified from: Leuven, R.S.E.W., van der Velde, G., Baijens, I. et al. Biol Invasions (2009) 11: 1989. https://doi.org/10.1007/s10530-009-9491-7
Neobiota are increasing biodiversity … or not?
After the last ice age, biodiversity in Central European rivers was low. The European fish fauna, for example, still bears less species than one of other continents that were not buried under ice (e.g. North Amerika). Most of the waters had to be recolonised – and fish and flying insect were the firsts, while less mobile invertebrates came after. Because of this, the original diversity of crayfish, for example, was never restored (Thienemann 1950).
THIENEMANN, A. (1950): Verbreitungsgeschichte der Süßwassertierwelt Europas. Die Binnengewässer 18, 809 S., Stuttgart.
Additionally, in densely populated Central Europe, most of the aquatic ecosystems are under heavy human influence. Some of the factors complicating the life of many aquatic organisms and therefore reducing biodiversity are:
- Exposure to plant nutrients (fertilizers) and other pollutants (e.g. from wastewater)
- Increasing water temperature through to power plants or the release of industrial cooling water
- Less river continuity trough to hydropower plants or locks
- Structural degradation of water bodies and therefore less different habitats through to modifications for shipping and flood protection.
Extreme events as floods (e.g. 2002 and 2013 in Elbe river) or droughts (e.g. summer 2003 and 2019 in Elbe river) or environmental disasters (e.g. fire at the Sandoz chemical plants in 1986 in Basel at River Rhine), are further reducing the biodiversity in our streams. It takes many years for river ecosystems to recover from such incidents.
Many invasive neobiota are especially robust and therefore they are able to colonize disturbed water systems or extreme habitats. Thus, one could say, all of these newly established mussels, crustaceans etc. are increasing the biodiversity. However, several of these non-native species are causing additional loss of native species due to high competition (e.g. about necessary food resources or already less available habitats). Because invasive species often have high reproduction rates, these species reach a high number in no time and can endanger native species in their newly populated habitat. Often, artificial structures and modifications for shipping and flood protection provide suitable habitats for these newly introduced species while native species are missing suitable habitats as retreats.
Data: Bundesanstalt für Gewässerkunde. Graph: S. Worischka
But invasive neobiota are not only found in Central Europe. As here, alien species have been or are being introduced intentionally and unintentionally all around the world and sometimes cause great ecological and economic damage. Especially, islands, which often have a particularly large number of endemic species, are severely hit by the introduction of invasive species. This is why some countries have very strict regulations in order to prevent further invasive species (e.g. in New Zealand).
Quiz #4
Wich of these (here) native species are considered as invasive neobiota elsewhere?
Brown trout
(Salmo trutta fario)invasive in Australia, New Zealand, North America and Japan
Freshwater pearl mussel
(Margaritifera margaritifera)not found outside it’s natural distribution range (northern parts of Eurpos, North America and Asia), species threatened with extinction
Eurasian ruffe
(Gymnocephalus cernuus)invasive in North America
Common or smooth newt
(Triturus vulgaris)invasiv in Australien
Stone crayfish
(Austropotamobius torrentium)not found outside its natural distribution range (few localities of Europe, Balkan peninsula), endangered species
Eurasian beaver
(Castor fiber)not found outside its natural distribution range (parts of Eurasia), endangered species
European bullhead
(Cottus gobio)not found outside its natural distribution range, partly endangered species,
European rabbit
(Oryctolagus cuniculus)invasive in Australia and New Zealand
Freshwater (brook) shrimp
(Gammarus pulex)invasive in Northern Ireland and at the Isle of Man
Common carp
(Cyprinus carpio)invasive in Australia, New Zealand and North America
Water soldier
(Stratiotes aloides)invasive in Canada/ North America
Eurasian otter
(Lutra lutra)not found outside it’s natural distribution range (Eurasia and northern Africa), locally declining
What can we do?
It is practically impossible to eradicate invasive neobiota once they are established. But for a useful management of these species it helps to recognize invasions early and restrict it as far as possible. Furthermore, maintaining or recreating retreat areas for native species can be of help. By river restoration and protection of near-natural river systems, suitable habitats of native species are preserved, which means that invasive neobiota may spread less explosively (because of higher competition) and their negative effects can be limited. Cross-border cooperation is important, as rivers and the species living in them do not know about borders. To do this, new strategies and solutions must be created. With the project MoBI-aqua, we want to contribute to this.
But you can help, too:
- Do not release alien species into the wild: exotic aquarium and pond pets do not belong in local waters!
- Avoid carryover: clean your fishing gear, buckets and boots/ waders before moving to another angling place.
- Clean your boat before relocating to another water body.
- Identify invasive species, distinguish them from native ones and report finds and observations, e.g. using the MoBI-aqua app.
- In some countries there are laws requiring removal of invasive neobiota according to EU-regulation. However, when in doubt, animal welfare and fishing regulations are dominant – catch up on laws and rules!
- Catches or live finds of neozoa must not be taken away or killed without fishing license and … of the respective country or state administration. However, rightfully caught gobies may be used for soup – recipes see Downloads.
- Last not least, everyone can help protecting habitats for the endangered biodiversity and mitigating climate change: Calculate your ecological footprint…