1. Pacific Red Starfish – Asterias amurensis
Asterias amurensis is a species of marine invertebrate originating from China, Korea, Russia, and Japan. This starfish species has proliferated into North America and Australia, causing severe impacts on native mollusk populations. In areas with high densities of this starfish, most bivalve species and sessile or fixed invertebrates are excluded.
(Image: afsc.noaa)
2. Green Crab – Carcinus maenas
The green crab originates from Europe and North Africa. It has been introduced to the United States, Australia, and South Africa. The green crab is an omnivorous predator, with a diet including bivalves, especially clams. In areas where green crabs have been introduced, they have led to declines in other crab species and bivalve populations.
(Image: tmu.uit.no)
3. Cercopagis pengoi
Cercopagis pengoi is a small crustacean native to the Caspian, Azov, and Arabian seas. This crustacean has invaded the Baltic Sea, Gulf of Riga, Finland, and the Great Lakes. Here, they have thrived and compete for food with fish, as a carnivorous crustacean consuming various aquatic animals, contributing to eutrophication.
(Image: bioresurs)
4. Zebra Mussel – Dreissena polymorpha
The zebra mussel originates from the Caspian Sea and the Black Sea. They have now invaded and adapted in the UK, Western Europe, Canada, and the United States. Zebra mussels compete with plankton for food, thus affecting the natural food web. They also impact the ecological functions of native mollusks and cause significant economic losses.
(Image: starfish)
5. Chinese Mitten Crab – Eriocheir sinensis
The Chinese mitten crab is native to Asia and has contributed to the extinction of native invertebrate species in many areas. They alter habitats through burrowing activities and cause annual losses of $100,000 in various industries, including fishing and aquaculture.
(Image: jjphoto)
6. Atlantic Sea Walnut – Mnemiopsis leidyi
The Atlantic sea walnut is native to the western Atlantic, but its population explosion in the Black Sea has caused significant changes to the ecosystem structure due to its predation on juvenile fish. Additionally, they also prey on planktonic mollusks and the larvae of crustaceans.
(Image: infovek)
7. Mediterranean Mussel – Mytilus galloprovincialis
The Mediterranean mussel has invaded South Africa and is competing with native black and brown mussel species. Sometimes referred to as green mussels, they can be confused with Mytilus edulis. This species has also been introduced to Hawaii and various locations in the United States.
(Image: aquamuseum)
8. Amur Clam – Potamocorbula amurensis
The Amur clam originates from Japan, China, and Korea, and has been introduced to the United States, causing severe harm to the aquatic environment there by competing for space with native benthic communities and decimating planktonic communities.
(Image: marine.csiro)
(The absence of species from this list does not imply they are less dangerous)
