This week is Invasive Species Week. Its aim is to raise awareness of animal and plant species that are not native to our country and whose presence causes disruption or environmental harm.
Some non-native species can be very common but cause little impact, such as horse chestnut trees and rabbits. However, when a non-native species causes harm to biodiversity, causes a cost to the economy or a threat to human health it is then classed as an invasive non-native species (INNS).
INNS are one of the top five reasons for biodiversity loss globally. They can outcompete native species, resulting in dramatic population declines and sometimes extinctions.
As well as a major threat to our biodiversity, INNS can result in large costs to the UK economy. Some invasive species like japanese knot weed cause damage to infrastructure by disrupting drainage systems, weakening retaining walls, and damaging property foundations.
Disrupting our water supply
As a drinking water-only company, there are some INNS that are of particular concern to us. Zebra mussels are a growing threat to our infrastructure and water quality. They stick together in large colonies and if they end up in pipelines, they can cause blockages disrupting water supplies and requiring costly repairs.
Himalayan balsam is another species that causes us problems. It is an annual species, which means it grows for one year and then completely dies back and doesn’t grow again. Unfortunately for us, it likes to grow on riverbanks. When it dies back in autumn, its shallow root system leaves the riverbanks exposed and when we have heavy rain, the exposed soil can wash off into the river.
This soil is then mixes within the water causing cloudiness (also known as turbidity) and reduces the river’s capacity to hold water, which can increase the risk of flooding in the local area. High levels of soil particles also make water harder to turn into clean drinking water.
It can also impact species that live in and around the river. Pollutants from fertilisers and pesticides can bind to the soil which can result in a rapid increase in algae. The excess algae uses a lot of the oxygen in the water, making less available for other species.
Although the plant produces beautiful flowers, the shape of them poses an issue to any pollinator species that are not large enough to open the flower and collect the nectar. This and its ability to outcompete native flowering plants means it has negatively impacted insect populations. Research has suggested that areas where the plant has taken over can see up to a 75% reduction in spiders, 64% in beetles and 58% true bug populations [CABI].
It's a challenging species to control as it is very good at spreading. Each plant produces around 800 seeds which it can fire up to seven metres. Its preference for riverbanks means its seeds can also be transported large distances across water ways and they can remain in the soil for two years.
This is why we proactively manage Himalayan Balsam on and around our sites. We engage local volunteers, community groups, and land managers in our Himalayan balsam control strategy, through our invasive species partnership project. This encourages local ownership of the sites, ensuring plants are consistently removed year after year.
How you can help the fight against INNS
We need everyone to help in the fight against invasive non-native species. If you visit any of our sites or use local water bodies for recreation, you can make a difference:
- Check, Clean, Dry (CCD): Always inspect your clothing, gear, and pets for mud and plant fragments, clean everything thoroughly, and ensure it is fully dry before leaving or moving to a new location.
- The Be Plant Wise: This is a national initiative that encourages gardeners and pond owners to protect the environment by choosing non-invasive plants, preventing their escape into the wild, and disposing of garden waste responsibly.
- Report Sightings: Use the INNS Mapper(opens in a new tab) to report any invasive species you come across.
- Learn More: Visit the Non-Native Species Secretariat website(opens in a new tab) for more information on the species of concern and how to prevent their spread.
Find out more about our work to control INNS(opens in a new tab).
Share this Article: