RAPID: What are INNS?

What are Non-Native Species (NNS)?

Non-Native Species (NNS) are those species found outside their normal or native range as a direct result of human activity. Some of these have been moved around the world accidentally on boat hulls or in ballast water or via the transport of goods and materials. Some species have been intentionally released for food or sport, e.g. pheasants, apple trees, or for horticulture, e.g. rhododendron and azalea. Some species may have been introduced many times before they have become established in the UK. When a non-native species is established and then becomes a problem to the local ecosystem or economy, it is labelled ‘invasive’ (INNS), sometimes referred to as invasive alien species (IAS).

Why should we worry about INNS in marine and freshwater environments?

INNS can often grow at tremendous rates, out competing native species for food, space and light. They can smother native species and potentially lead to a mono-culture which can destroy entire ecosystems. They can also clog or damage important infrastructure such as water intakes, fish cages, propellers and lock gates in aquatic environments. INNS are thought to be one of the greatest threats to biodiversity and Defra have estimated that they cost the British economy at least £1.7 billion per year to control.

Rope fouled by trumpetwormPhoto © Christine Wood

Rope fouled by trumpetworm

How are INNS spread?

INNS can be released and spread through many different pathways in the freshwater and marine environments including:

  * Fouling of recreational equipment, e.g. diving gear, fishing lines, kayaks, ropes, dinghies, clothing

  * Hull fouling of commercial or private vessels

  * Ballast water exchange

  * Distribution in water especially at the planktonic stages or by plant fragmentation

  * Escape or release of plants and animals from aquaria

  * Importation or movement of new species (historically), shellfish or stock for aquaculture

  * Organisms attached to structures and subsequently relocated e.g. pontoons, dredges

  * Intentional release by individuals

Aquatic Invasive Alien Species (Click here for video)

This animation gives an overview of INNS, how they may arrive, and biosecurity measures to prevent spread.

Thin strip of image show tree trunk and bark