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The hidden costs of invasive species

  • Written by  Laure Boissat
  • Published in UK
A grey squirrel, one of many invasive species putting a strain on the UK’s expenses A grey squirrel, one of many invasive species putting a strain on the UK’s expenses (Image: Shutterstock)
09 Apr
2018
The UK’s withdrawal from the EU is likely to lead to a surge in management costs of invasive non-native species in the UK, a task that currently amounts to £2bn annually

It only takes a carefree stroll around Hyde Park to encounter non-native species. What an untrained eye perceives as a typical red-furred rodent is in reality more likely to be a grey squirrel, as the latter species has outcompeted its red counterparts throughout Europe’s woodlands. The Wildlife and Countryside Link (WCL), a coalition of 12 conservation charities, is calling for government action as the costs necessary to manage such non-native species are likely to soar as the UK leaves the European Union.

The grey squirrel is one example among many of non-native species thriving in the UK (see table below). Known as ‘alien species’ in the Convention on Biological Diversity (CBD), the term ‘non-native species’ refer to a species introduced by human action in an area that is not the species’ natural environment (for instance, it has been well-documented that grey squirrels were introduced to the UK from the USA in the late 19th or early 20th century). It is important to distinguish ‘non-native’ from the notion of ‘invasive’ species, the latter being defined by the Non-native Species Secretariat (NNSS) as any non-native animal or plant that has the ability to spread causing damage to the environment, the economy, human health or way of life.

Six of the worst invasive species in the UK and their costs to the economy
 Species and damage caused  Estimated annual cost to the economy in 2017*
Japanese knotweed is found in almost all British constituencies. It damages habitats, increases soil erosion and flood risk, impacts on railways, highways and buildings, and is expensive to eradicate. over £200million
New Zealand flatworms prey upon worms and snails, reducing soil fertility and food production. Earthworm numbers are down in some areas by 75 per cent. The impact is worst in Scotland and Northern Ireland. Flatworms and many other invasive species are regularly imported in soil and pot plants. £34million in Northern Ireland and £23million in Scotland
Grey squirrels cause: tree damage by bark-stripping, exposing timber to fungal and insect attack; damage to household lofts and cables; and the decline in red squirrels through outcompeting and disease. Over £17million
Mink threaten poultry and fish farms, they also kill gamebirds, other ground-nesting birds and are responsible for declines in water vole populations, with a 30 per cent fall in water vole sites between 2006-2015 Over £6.1million
Australian swamp stonecrop is one of the most damaging and invasive aquatic plants, forming dense mats which smother other plants. Once established it is almost impossible to get rid of. Over £3.6million
The North American Signal crayfish has wiped-out whole populations of the native White-clawed freshwater crayfish through predation, competition and transmission of crayfish plague.

Over £1.8million

* Note that the figures in this table are from a number of studies which have been updated to account for inflation, using the Bank of England inflation calculator. The figures are very likely an underestimate of the cost to the economy as the spread is likely to have increased from the time of the studies referenced. These are determined to be six of the worst invasive species due to their notable spread, damage caused, cost to the economy, and/or their difficulty to eradicate.

How costly can an innocent-looking squirrel be costly to the UK economy? A 2010 report by the Centre for Agriculture and Biosciences International (CABI) highlights that the impacts of Invasive Non-Native Species (INNS) can be manifold, ranging from crop loss and damage to buildings, to the loss of livelihoods and ecosystem services. The report estimates the total annual cost of INNS to the British economy reaches approximately £1.7billion which, once adjusted for 2017 levels using the Bank of England inflation calculator, equates just over £2billion. In 2016-17, the government spent approximately £922,000 on biosecurity measures – this cost is broken down into £145,000 for policy functions, £90,000 on risk analysis, £335,000 for early warning and rapid response measures, £210,000 on coordination, £80,000 on communication and awareness raising activities, and £62,000 on research.

More worrying is the prediction that these costs are set to rise post-Brexit according to WCL. ‘Nature invaders are a big post-Brexit economic threat,’ says Hannah Freeman, senior government affairs officer at Wildfowl and Wetland Trust, one of the NGOs belonging to the WCL consortium. These mounting costs associated with invasive species management are largely due to new economic trading patterns that will emerge  once the UK leaves the EU. ‘Opening our doors to new trade post-Brexit also opens the door to new nature invaders,’ says Dr Elaine King, director at WCL.

Mink costs the UK an estimated £6.1million annually in control costsMink cost the UK an estimated £6.1million annually in control costs (Image: Shutterstock)

International trade is the most common way invasive non-native species travel across the world and end up in new habitats, either by being traded goods themselves or by being inadvertently transported along a trading route. Although it is hard to precisely forecast what post-Brexit trade will be, the UK’s current non-EU trading partners are expected to grow in importance, thus increasing the risks that new species will be brought onto the British territory. ‘Prevention is better than cure,’ highlights Camilla Morrison-Bell, chair of the INNS Group at WCL. She adds that ‘we need better resourcing for the work of enforcement agencies, backed up with legislation, to tackle the increasing nature invader threat.’

Shipping has also been identified as a major pathway for introducing species to new environments. The WCL coalition points out that a strict enforcement of the Ballast Water Management Convention is still lacking in the UK. Adopted in 2004, but entered into force only in 2017, this international treaty aims to prevent the spread of harmful aquatic organisms from one region to another by establishing standards and procedures for the management and control of ships’ ballast water and sediments.

Australian swamp stonecrop is one of the most damaging and invasive aquatic plants (Image: Shutterstock)Australian swamp stonecrop is one of the most damaging and invasive aquatic plants (Image: Shutterstock)

In addition to opening new trade routes, there are risks that climate change increases the likelihood of non-native species thriving in the UK, hence becoming invasive. As temperatures are getting higher, certain species that would not normally be adapted to the British cold winter could now outcompete or kill native wildlife and plants. As such, a study by Queen’s University Belfast predicts that invasive waterweeds will become more widespread over the next 70 years due to a rise in temperatures.

At present, the UK legislative framework regulating non-native and invasive species largely derives from the EU Regulation on Invasive Alien Species. In addition to listing invasive alien species of concern for the Union, the European Commission envisages three types of measures to deal with invasive species – preventing non-native species from entering the EU, rapidly detecting and eradicating the species to, finally, setting up a concerted management plan among several EU member states. The regulation came into force in 2015 and currently applies restriction on 49 invasive non-native species.

Even though the UK government has stated its commitment to fully retain this regulation, there remain doubts on how this will be achieved. WCL underscores that even though the EU regulation is duly translated into UK domestic law, the provisions making it strong in the first place would be lost. Such provisions refer to, notably, the six-yearly requirement to report to the European Commission on the actions taken to implement the Regulation.

The North American Signal crayfish has been sighted in the Midlands (Image: Shutterstock)The North American Signal crayfish has been sighted in the Midlands (Image: Shutterstock)

Danny Heptinstall, policy officer at the RSPB explains explains that though the impacts of Brexit are still uncertain, leaving the EU might well present an opportunity for the UK to seize, in order to assert itself as a leader in biosecurity as the country looks to exert tighter trade controls. As such, the WCL coalition calls upon the government to back up the 2015 GB Non-Native Species Strategy with necessary funds to ensure it efficiently deters illegal activities that could cause invasive species to spread. The strategy will also need the force of the law after Brexit in order to be enforceable. WCL thus highlights that the precautionary and ‘polluter pays’ principle should be kept in post-Brexit UK law as ‘Preventative and early action is substantially more cost effective than eradication,’ says Camilla Morrison-Bell.

When it comes to invasive species, the precautionary principle states that action should be taken to avoid serious or irreversible environmental harm, even though the scientific certainty of such harm has not been fully established. The polluter pays’ principle, on the other hand, requires EU member states to adopt penalties in domestic legislations to dissuade parties from spreading invasive species (up to £1,000 for individuals; £3,000 for businesses). When the UK formally withdraws from the EU, international cooperation with regards to invasive species will remain necessary. ‘Like many current ecological challenges, invasive species are of regional and even global concern. Continued information exchange and collaboration between countries is essential if this growing issue is to be tackled effectively,’ says Morrison-Bell, adding that a post-Brexit UK-EU cooperation ‘should include retaining access to the EU information system for invasive alien species, which provides a framework for early warnings and coordinated rapid response plans.’

Japanese knotweed is one of the most recognisable forms of invasive species, found in gardens across the country (Image: Shutterstock)Japanese knotweed is one of the most recognisable forms of invasive species, found in gardens across the country (Image: Shutterstock)

Members of the public also have their role to play when it comes to preventing and managing the introduction of new species. In an attempt to raise awareness on the matter, DEFRA and the NNSS board launched the Invasive Species Week in 2015. Having run through March, the week brought together organisations and individuals to foster dialogue on invasive species management. Morrison-Bell underscores that technology can help us better understand non-native species population patterns, for instance through citizen science initiative or apps. ‘These high-risk species can then be monitored to better understand their possible ecological impacts and to mitigate their spread before they become invasive,’ she says.

As a species cannot be labelled ‘invasive’ without a robust risk assessment, it is also important to note that even though the 2010 report on invasive species solely focuses on the negative economic impacts of INNS, it still acknowledges that some non-native species can make a positive contribution to the environment. In the UK, man-made coniferous forests grown for timber production for instance provide a cherished habitat for the now quite rare red squirrel.

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