Invasive species - rogues' gallery
Not all the plants and animals living in our canals and rivers are native to the UK. Some species have been introduced, often with disasterous results for our precious ecosystems.
Invasive species can cause devastating effects to native wildlife, competing for food, space, sunlight, and water. The animals can often be bigger and more aggressive, while the plants choke canals and rivers with their rapid growth.
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Mink
American mink first arrived in Britain in 1929, but only in commercial fur farms. They were first reported to be breeding wild in the UK in 1956, as a result of escapees and deliberate releases. Today it is virtually impossible to estimate the number of mink living in our waterways. -
Giant Hogweed
This former ‘beauty queen’ of 19th century ornamental gardens can now be found along waterways and areas of wasteland, reaching heights of up to five metres. -
Terrapin
Britain's inland waterways were a safer place for bird eggs and insect larvae before these reptiles came along. -
Floating pennywort
Introduced to the UK in the 1980s by the aquatic nursery trade, this fleshy-stemmed plant uses its roots to inter-weave a floating mat of lush foliage. -
Japanese knotweed
One of the most invasive weeds in Britain, the Japanese Knotweed’s dense growth crowds out native vegetation, erodes riverbanks and causes structural damage. -
New Zealand Pigmyweed
New Zealand Pigmyweed, also known as Australian Swamp Stonecrop, was originally sold in garden centres as an ‘oxygenating plant’. -
American signal crayfish
Found throughout England, these 15cm long beasts are aggressive, breed faster than the native species, and damage banks with their burrowing. -
Water Fern
This popular pond plant, originally native only to North and Central America, is also known as Fairy Fern. -
Zander
This wide-mouthed predator has excellent vision and fang-like teeth, which it uses to eat native fish and steal their food. -
Himalayan Balsam
Despite its soothing name, this densely growing pink and red-stemmed weed stifles any native grasses and plants in its path. -
Chinese mitten crab
The Chinese mitten crab takes its name from its large, white-tipped claws, which are covered in soft fur. -
Zebra Mussel
These stripy stowaways landed in Britain’s waterways on the hulls of ships from Eastern Europe and decided to stay. -
Killer shrimp
Killer shrimp (Dikerogammarus villosus) is a highly invasive shrimp which can be considerably larger than our native shrimps, growing up to 30mm in length and usually has a striped appearance, although it can be uniform in colour.
