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

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?

Alopochen aegyptiaca

Egyptian goose

(Alopochen aegyptiacus)

North Africa

Neogobius melanostomus

Round goby

(Neogobius melanostomus)

Black Sea and Caspian Sea basins

Dikerogammarus villosus

Killer shrimp

(Dikerogammarus villosus)

Black Sea and Caspian Sea basins

Ondatra zibethicus

Muskrat

(Ondatra zibethicus)

North America

Aix galericulata

Mandarin duck

(Aix galericulata)

East Asia

Ameiurus melas

Black bullhead catfish

(Ameiurus melas)

North and South America

Asian clam

(Corbicula fluminea)

Asia, Africa and Australia

Procyon lotor

Raccoon

(Procyon lotor)

North America

Impatiens glandulifera

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)

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)

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)

potato

Native species

Wrong

Archaeobiota

Wrong

Neobiota

Right

Tomato (Solanum lycopersicum)

Native species

Wrong

Archaeobiota

Wrong

Neobiota

Right

Wheat (Triticum sp.)

Triticum sp

Native species

Wrong

Archaeobiota

Right

Neobiota

Wrong

Round goby (Neogobius melanostomus)

Native species

Wrong

Archaeobiota

Wrong

Neobiota

Right

Pumpkinseed (Lepomis gibbosus)

Lepomis gibbosus

Native species

Wrong

Archaeobiota

Wrong

Neobiota

Right

Chinese mitten crab (Eriocheir sinensis)

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)

Salmo trutta fario

Native species

Right

Archaeobiota

Wrong

Neobiota

Wrong

Stone crayfish (Austropotamobius torrentium)

Austropotamobius torrentium

Native species

Right

Archaeobiota

Wrong

Neobiota

Wrong

Common carp (Cyprinus carpio)

Cyprinus carpio

Native species

Wrong

Archaeobiota

Right

Neobiota

Wrong

Roman snail (Helix pomatia)

Helix pomatia

Native species

Wrong

Archaeobiota

Right

Neobiota

Wrong

Touch-me-not balsam (Impatiens noli-tangere)

Impatiens noli-tangere

Native species

Right

Archaeobiota

Wrong

Neobiota

Wrong

European rabbit (Oryctolagus cuniculus)

Oryctolagus cuniculus

Native species

Wrong

Archaeobiota

Right

Neobiota

Wrong

Common or smooth newt (Triturus vulgaris)

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

Neogobius melanostomus

Round goby, (Neogobius melanostomus) © S. Worischka

Alopochen aegyptiaca

Egyptian goose (Alopochen aegyptiacus) © S. Worischka

Faxonius limosus_habitus

Spinycheek crayfish (Faxonius limosus) © P. Kozak

fallopia japonica

Asian knotweed (Fallopia japonica) © S. Worischka

Impatiens glandulifera

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

Salvelinus fontinalis

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!

Ctenopharyngodon idella

Grass carp (Ctenopharyngodon idella)

introduced as ornamental fish

True

False! Correct is: introduced as pest plant control

False

This answer is right!

Cyprinus carpio

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!

Egeria densa

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!

Eriocheir sinensis

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!

Helix pomatia

Roman snail (Helix pomatia)

introduced by the ancient Romans as food snail

True

This answer is right!

False

This answer is wrong!

Impatiens glandulifera

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!

Neogobius melanostomus

Round goby (Neogobius melanostomus)

“stowaway: in the ballast water of ships

True

This answer is right!

False

This answer is wrong!

Dikerogammarus villosus

Killer shrimp (Dikerogammarus villosus)

“stowaway: in the ballast water of ships

True

This answer is right!

False

This answer is wrong!

Oncorhynchus mykiss

Rainbow trout (Oncorhynchus mykiss)

introduced as edible fish

True

This answer is right!

False

This answer is wrong!

Aix galericulata

Mandarin duck (Aix galericulata)

introduced as ornamental birds

True

This answer is right!

False

This answer is wrong!

Lepomis gibbosus

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)63276
Zebra mussel (Dreissena polymorpha)65199
Caspian mud shrimp (Chelicorophium curvispinum)44137
Killer shrimp (Dikerogammarus villosus)112461
Pontic waterlouse (Jaera sarsi)109185
  • 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.

Aquatic biodiversity is already reduced or even endangered in many place in Central Europe.

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

Therefore, more neobiota does not mean a higher biodiversity.

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?

Oncorhynchus mykiss

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

Triturus vulgaris

Common or smooth newt

(Triturus vulgaris)

invasiv in Australien

Austropotamobius torrentium

Stone crayfish

(Austropotamobius torrentium)

not found outside its natural distribution range (few localities of Europe, Balkan peninsula), endangered species

Castor fiber

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,

Oryctolagus cuniculus

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

Cyprinus carpio

Common carp

(Cyprinus carpio)

invasive in Australia, New Zealand and North America

Water soldier

(Stratiotes aloides)

invasive in Canada/ North America

Lutra lutra

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…