Invasive Alien Species have a good start in freshwater and riparian environments!

Invasive Alien Species in freshwater and riparian (river side) habitats- some facts for concern:

  • Once Invasive Alien Species become established in freshwater and riparian  areas – it is very challenging if not impossible to successfully eradicate them.
  • While the majority of invasive alien species are found in the terrestrial environment, the rate if increase in introductions is greatest for the freshwater environment since 1980.
  • Freshwater non-native species are more likely to be high impact invaders when they are introduced.

What are the challenges of  invasive alien species in freshwater and riparian areas?

As we spend most of our time out of the water, we are more likely to spot when an unusual or new species has arrived and established in an area on land. This means that often invasive aliens species are well established in our freshwater long before they are detected. The longer they have been there, the more time the species has  to reproduce and spread and the harder it can be to remove them. In connected waterways such as from lakes to rivers etc, the natural movement of water is a fantastic ‘express highway’ for the invaders to travel to new sites. The other wildlife in the water or even the movement of people and their equipment from one waterbody to another  to another can also aid their spread.

Invasive Alien species living along riparian areas also have access to a good route for movement to new sites. Whether it be by exploding seed into a river (Himalayan balsam) or spreading by plant fragments after floods have broken a bit off (the invasive knotweeds) or just by swimming to new sites (Coypu, Sliders etc). What a great start to invasion invasive alien species can have in freshwater and riparian areas!

Due to limitations on available control methods for removing invasive alien species from in or beside the water and, the risks of reintroduction from ‘up-stream’ sites, eradicating an invasive species from riparian and freshwater areas can be very challenging if not impossible. Impossibility may also factor-in unwanted impact on other wildlife that can’t be avoided, no effective method of control or even just the monetary cost making it unfeasible.

How we can all help. 

We have to prevent introduction of invaders to these areas. If they are already present, we have to try to prevent their further spread. For information on how may be able to help prevent introduction and spread of invasives to protect or freshwater and riparian areas check out the Check, Clean, Dry, the Be Plant Wise and Be Pet Wise campaigns.

Check out below some of the species profiles for some of the riparian and freshwater species in Ireland. If you see them, take a photo if you can and report the sighting through the online form or by the Biodiversity Data Capture App .


Click on image to access species profile information.

American skunk cabbage

Giant hogweed

Curly waterweed
Curly waterweed

Nuttall’s waterweed

Giant Chilean rhubarb

Water primrose
Water primrose

Parrot's feather
Parrot’s feather

Himalayan balsam


Ruddy duck

Yellow-bellied slider

Red-eared slider