Invasive Species Alerts Affecting Inland Waterways

Created on 30/03/2017

Invasive species cause substantial damage across the globe. In the UK invasive non-native species are estimated to cost the economy approximately £1.7 billion a year.  For this reason it is important that the situation is regularly monitored.  Invasive alerts are put out by the Non Native Species Secretariat (NNSS) in order to increase vigilence, reduce the spread and eliminate invasive species deemed a risk to the UK’s environment.

Invasive species threaten canal and river ecosystems as well as creating problems for waterway users. Of the five current NNSS species alerts, three of them directly affect UK inland waterways.

Water Primrose - Ludwigia grandiflora

A very recent invader to the UK - Water Primrose is a proliferate semi-submerged plant which is native to South America and prefers slow moving water bodies.  Introduced as a garden plant, Water Primrose has spread into water courses where it rapidly colonises and spreads. Identified in sites primarily across south England and Wales this plant negatively impacts the local environment through outcompeting native species.

How to identify

Water Primrose can be difficult to identify especially if it growing in proximity to other native semi-submerged flora.  The characteristics to look out for are:

  • Bright yellow flowers with five petals (July – August)
  • Dark green leaves with a lighter central vein, the shape of the leaves can vary from long and thin to oval.
  • It grows upright as well as spreading across a water body 
  • Seed cases are distinct with star shaped vegetation at the base

Ludwigia grandifloraPhoto: Water Primerose (photo by: Krzysztof Ziarnek, Kenraiz (Own work), via Wikimedia Commons)

Killer Shrimp - Dikerogammarus villosus

Not your obvious invader but these small invertebrates are voracious predators that hunt other invertebrates and small fish. Native to the south-east regions of Europe this shrimp is a hardy species that can tolerate poor water quality and survive in damp conditions for up to five days. This means that they can be spread by ballast water and survive in water retained on waterway kits such as kayaks, boats and angling gear. Killer Shrimp are mostly found in habitats with artificial banks, high oxygen saturation and low conductivity which make canals a highly viable environment for this species to colonise and spread.

How to identify

Despite being the largest of the shrimp found in the UK between 10-20mm (but sometimes up to 30mm) this species may very well pass you by unnoticed. However if you happen to see a shrimp the signs to look for are:

  • Black banding across its whole body
  • Distinctive cones on their tails (native shrimp have smooth tails)

Killer Shrimp

Photo: Killer Shrimp (photo by: Michal Grabowski (own work)   Live specimen of Dikerogammarus villosus - Killer Shrimp)

Quagga Mussel - Dreissena bugensis

Identified as the highest risk future invasive to the UK, Quagga Mussel is regarded as an ecosystem engineer with the capabilities to completely alter marine environments. Established Quagga Mussels filter out the nutrient rich phytoplankton which effectively clears its environment allowing more light to reach the waterways floor and encouraging the growth of problem weeds. This also reduces available food for native fish and invertebrates. The Quagga Mussel is even more invasive than the Zebra mussel and is a major threat to native mussels as it will outcompete and suffocate existing colonies. This prolific breeder is also a biofouling threat to structures such as pipes, boats and lock gates.

How to identify

Small with alternating light and dark brown stripes (similar to the zebra mussel) but can also be solid in colour as well.

  • Triangular in shape and usually less than 5cm in length
  • Has an undulating seam between the valves (shells)
  • Will roll onto its site when placed on its front (unlike the Zebra Mussel)

Dreissena bugensis

Photo: Quagga Mussel (photo by: Motte123 (Own work), via Wikimedia Commons)

Controlling Invasives

You may not be aware that you could be helping the spread of invasive species across UK waterways. With these three simple steps promoted by NNSS you can help protect wildlife, mitigate problems for waterway users and prevent unnecessary damage to waterway infrastructure.

Check - your equipment and clothing for live organisms, particularly in areas that are damp or hard to inspect.

Clean -  wash all equipment, footwear and clothes thoroughly. Use hot water where possible. If you do come across any organisms, leave them at the water body where you found them.

Dry - all equipment and clothing; some species can live for many days in moist conditions.

Report and record

It is important that invasive species on the alert list are reported to the appropriate management body to control their spread.  This can be done online through iRecord or RISC (Recording Invasive Species Counts)

More information

More information on the Check, Clean, Dry campaign & invasive species is available at the GB Non-native Species Secretariat website.

Don't forget to read about other invasive species you can find on our waterways.


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