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Marine non-native species

Invasive non-native plant and animal species are one of the greatest threats to biodiversity worldwide. They can have negative impacts on native species and can threaten whole ecosystems causing serious problems to both the environment and the economy. In Scotland, there is a growing problem with marine invasive non-native species

What do we mean by invasive?

Not all non-native (alien) species are bad. Many species that have been introduced to Scotland are now an important part of Scotland's diversity and industries. However, a minority have serious negative impacts on native Scottish habitats, our health or our economy. These species are invasive non-native species external site .

What species are here?

Some marine invasive non-native species have become widespread and well established in Scotland, including:

Other marine invasive non-native species can only be found in isolated or sporadic locations within Scotland, including:

What other species are likely to arrive?

The following examples are species that are in, or are close to, the British Isles but have yet to reach Scotland:

What problems do they cause?

The potential impact of invasive non-native species at sea can be significant, resulting in both biodiversity and economic implications. Away from their native habitats, invasive species are often able to grow very large and very quickly and can displace native species. They can become the most dominant species in the area and some can smother other creatures.

Invasive species can have impacts on our marine industries. For example, invasive seaweeds can grow on structures such as piers, slipways, fish-farm cages, boat hulls and can become entangled in boat propellers. Other species can kill or compete with species used for aquaculture, and can spread disease.

How do they get here?

There are a variety of activities that can transport non-native species around the world and contribute to the spread of species between regions. These include: shipping (attached to boat hulls or in ballast water); the transport of fish and shellfish for the seafood industry; scientific research and public aquaria. The release of non-native species can be either accidental or intentional.

How do we deal with them?

Once established, it is extremely difficult to get rid of an invasive species in the marine environment. It is therefore more important to prevent the species arriving here in the first place. Marine biosecurity plans are a critical step in providing a framework to reduce the risk of introduction (more information on this can be found within the related links). 

If a species does arrive in our waters, early detection is essential if any attempt at clearing is to be made. For species that are apparent in isolated or sporadic locations, a level of containment or population management may be possible. However once a species is abundant or widespread, eradication is likely to be impossible.

How are they regulated?

For more information on the law, management and regulation of non-native species see SNH's Safeguarding Biodiversity Non-native species page.

Last updated on Wednesday 31st August 2016 at 10:02 AM. Click here to comment on this page