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Invasive Species

Non-native invasive species are described as flora or fauna which have been introduced to an area outside its natural range which subsequently have serious negative impacts on our native wildlife. Invasive species take over, killing native wildlife and are considered the second biggest threat to biodiversity globally. There are a number of non-native invasive plant and animal species in the Arun and Western Streams catchment. These are threatening our wildlife, food production and can increase flood risk. The species which are having the greatest impact in the catchment are summarised below:

Himalayan Balsam: is a large annual plant, with recognisable pink flowers. Its seeds burst from the plant and are easily spread along river banks. Their shallow roots are contributing to erosion and sedimentation, and it’s rapid growth smoothers native species.

New Zealand Pygmyweed, Parrots Feather and Floating Pennywort: All grow on, or just below the water level on lakes and rivers. This blocks sunlight, out competing our native plants and reducing biodiversity. Furthermore, its excessive growth can clog water courses and increase flood risk.

Japanese Knotweed: grows vigorously, and is often seen along riverbanks and hedgerows. It’s root system can damage concrete foundations, potentially causing serious damage to buildings. It over takes native plant species and can also reduce the capacity of flood defences to carry water.

Giant Hogweed: grows to over five metres tall, smothering native plant species. Furthermore, the poses a significant health risk to human health, as the sap from the plant can cause blisters and even blindness if it comes into contact with the eyes.

American Mink: are aggressive predators present throughout the catchment. They have a significant impact on native wildlife, especially fish and water voles.

Signal Cray Fish: which originates from America, spreads a fungal disease that kills native Cray Fish species. Furthermore, the Signal Cray Fish are strong predators, and can decimate fish and insect communities.

The ARC project funds a full time Conservation Officer who is leading the work to tackle this problem. It’s a big challenge and will require collaboration with landowners and armies of volunteers, but we hope that together we can make a big difference to restore the health of our rivers.

We are encouraging people to use iRecord and the Plant Tracker app to share your wildlife sightings. The goal of iRecord is to make it easier for wildlife sightings to be collated, checked by experts and made available to support research and decision-making. Join iRecord now to share your sightings, explore dynamic maps and graphs of your data and make a real contribution to science and conservation. The Plant Tracker app is focused on identifying the spread of invasive species, by recording the sightings when you are out and about. Download the Plant Tracker app and help identify invasive species in the catchment. Plant Tracker feeds into iRecord. If you don’t have a smart phone, then you can take notes and submit the record directly into iRecord.

For further information see: