The charity making life better by water

Tackling invasive species

Ecologist Tom King has outlined why tackling invasive species helps make life better by the water for everyone who visits.

Why are invasive species such a problem?

More than 50 non-native species have been accidentally introduced into our canals, rivers and lakes from all over the world, and numbers are rising rapidly. This is potentially going to get worse with climate change.

They can cause major damage. They out-compete native wildlife, damage eco-systems and spread disease. They can also block canals, forming a thick green carpet which restricts navigation, clogs up propellers and damages boats. Every year it costs us hundreds of thousands of pounds to clear away unwanted vegetation and manage the delicate eco systems which exist in many of our waterways.

What harmful plants and animals do we need to watch out for?

People tend to know about things like signal crayfish from North America, Japanese knotweed or giant hogweed. But there are dozens of other problem species. These include non-native fish that gobble up all the other fish around them, and small invertebrates, like freshwater shrimp, that you may not even realise are there. Then there are lots of plants that may look nice, but can cause enormous damage to local biodiversity.

Plants, like floating pennywort or curly waterweed can grow quickly and thickly, up to 20cm a day. This rapid spread means that they then block the water, which in turn makes it hard for powered boats, sailing boats or even paddle sports to get around. Its rapid growth prevents people from using the water and there is a huge cost to keeping a passageway through clear of weed.

Other, not so obvious issues, include non-native freshwater mussels. As these are underwater, you may not see them. Species like zebra (picture below) and quagga mussels can grow inside pipes and water-cooled engines, which then result in big costs for the asset companies that need to clear them out.

Zebra mussels in line on rock

Quagga mussels have even been found in an isolated Anglian Water reservoir in Lincolnshire. The nearest other known place with quagga mussels is in London, over 140 miles away. So how did this species travel overland such a long distance? It most likely hitch-hiked on a person, on their equipment, tools or machinery. Some species can survive for days, even up to a week, in damp equipment.

For anyone living near a river colonised by Himalayan balsam, you'll know it can take over and crowd out other plants. This is bad for insects, mammals and birds. Himalayan balsam dies back every autumn, which then leaves the riverbanks bare and can lead to erosion and flooding.

How can everyone help?

Watch to find out how waterway workers, contractors, marinas, boat yards and hire boat companies can help with invasive species.

How you can join the fight against invasive non-native species

One of the most important things everyone can do is stop the spread of harmful plants and animals to a new area.

There are three simple steps to remember: Check, Clean, Dry. They should be done before you leave a waterway, even if you are moving to another spot on the same waterway just a few miles away.

The first step is to Check any clothing, tools or equipment that have come into contact with the water, or even mud around water. Even the tread on your bike or the fur of your dog might be carrying an invasive species. If you find any plant fragments or animals, remove them and leave them at the site. Ideally, bin them, but always make sure they can't get back into the water.

Second step is to Clean your clothing, tools or equipment. Ideally with hot water, but a good rinse with clean cold water will also dislodge bits of plants and young animals that you can't see. Use a bottle of fresh water if you have one handy, or wash things down with a hose. Try and do it on a surface where the water can drain into the ground.

The last step is to Dry everything completely. Ideally in the sun, leaving no damp patches. Don't forget about clothes as well, things like wet suits, waders and boots. Small invertebrates can live for days in damp folds in clothing and seeds can get stuck in the tread of muddy boots.

Last Edited: 02 January 2024

photo of a location on the canals
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