Enhancing Biodiversity

Invasive Non Native Species (INNS)

Non Native species are animals or plants that have been introduced outside of their natural range whether deliberately (for agriculture, cultural and economic benefits) or accidentally. Many Non Native species are harmless or beneficial.  However, some of these Non Native Species are able to spread and to cause damage to our environment, the economy, or to human, animal or plant health and the way we live. These are termed Invasive Non-Native Species (INNS). INNS threaten our native species, ecosystems and habitats in many ways. They can compete with native species, or prey upon them. They may modify habitats or spread diseases.  INNS are one of the greatest threats to biodiversity worldwide.

The Yorkshire Dales Biosecurity and Invasive Non-Native Species steering group

The Yorkshire Dales Biosecurity and Invasive Non-Native Species steering group was established in 2015 to develop a strategic and coordinated approach to biosecurity and the management of INNS in the Yorkshire Dales comprising land included in the Yorkshire Dales National Park and the Nidderdale Area of Outstanding Natural Beauty.

Click on the pictures to find out more information 

Top Five Aquatic INNS


Water temperature affects all physical, chemical and biological process within the freshwater environment. Most aquatic species have a specific temperature range they can survive in. Salmonids require temperatures between 5-15 degrees, however over 22 degrees for a sustained period of time can be lethal.

Historically, rivers across the UK where more densely shaded, however majority of this tree cover has been lost resulting in rivers lack shade and cover. Riparian tree cover is very important in reducing local stream temperatures, up to 3 degrees in summer months and maintain a more constant water temperature.

Therefore it is important to increase the amount of riparian tree cover. There are also additional benefits to tree planting such as providing food, habitat and maintaining more natural stream functioning.

Read more from the Woodland Trust’s Keeping Rivers Cool manual.

Physical Modifications

Over thousands of years people have made changes to the physical structure of the river, such as altering the rivers course and installing flood defenses and weirs. Many of these changes have benefited society, for example by improving navigation, reducing flood risk, generating power and powering mills, improving drainage or allowing water abstraction. However, there is also ecological damage resulting from the changes.

  • Barriers to Fish: Weirs block the migration of fish travelling back upstream to spawn.
  • Straightened channels (Channelisation): These rivers have low habitat diversity and cannot support diverse communities of invertebrates, fish and their predators.
  • Reinforcing rivers: This can prevent natural processes and result in low habitat diversity and ins tram structure,
  • Culvert: Culverts create unnatural habitat, generally low light conditions and can also impede migratory routes for aquatic species.

The biggest reason (29%) that waters in our catchments are not healthy is due to changes to their shape and flow caused by physical modifications.