Module 2 Impacts of invasive species

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1 Module 2 Impacts of invasive species Nearly all invasive species over the last 500 years have been introduced by man. In many cases there have also been economic and cultural impacts on people. There are 2,000-plus non-native species of animals and plants that are estimated to have found their way here to the UK. Plant collectors Not all are deadly invaders. Some non- natives, such as the horse chestnut (origin Asia), has become highly accepted; but some can wreak havoc, crowding out precious native species, spreading parasites, stealing food sources and blanketing waterways.

2 There are many cases of invasive non-native species causing the extinction of island and continental species. Muntjac deer was introduced from south China by the Duke of Bedford to his estate at the turn of the century and now it appears to be causing problems. Then there's the American mink, which was brought over for fur farming but when the protesters cut the fence to free the mink it was caused massive declines in many species including ground nesting birds, such as puffins, and water voles (declined by 95% in 20 years). In the British countryside they have no natural predator and they themselves are voracious predators. Another example is the ruddy duck which was an escapee from a water park now subject to an eradication programme before it wipes out the native white-headed duck by hybridising with it. One of the many titanic battles against invasive species is currently being fought at Breamore Marsh in the New Forest. The marsh, a Site of Specific Scientific Interest, is the kind of place ecologists and botanists make pilgrimages to. In August 2009, a botanist went there to monitor a rare native plant and came back with a sample of something altogether more disturbing. It was from a small patch of Creeping

3 Water Primrose. By the time it had been confirmed and a case officer got down there in the beginning of October it had spread so far across the pond that they initially thought they must have the wrong site. It had an extremely rapid rate of spread. At Breamore there is concern that an outflow from the pond could potentially allow fragments of the invasive plant into the nearby river Avon, which is why a team of volunteers is periodically to be seen waist deep in the cold, murky water, painstakingly pulling out the tendrils by hand. On one November day alone they extracted 40 bags of the stuff. Funding to eradicate it continued up to 2013 it is still there despite 4 years of eradication work. Economic impacts Invasive species can have massive impacts on ecosystems by upsetting the natural balance but they can also become costly to eradicate. For example: Estimated costs for eradication of Japanese Knotweed in the UK: 1.56 Billion to treat all knotweed in the UK 56 Million to treat all knotweed in Wales There are nearly 11,000 NNS in the European Union and 10%-15% are negative Estimated cost of eradication or control in the EU is 12.7 billion per year. In the United States it is estimated that non-native species cost the US $137 Billion a year. Hawaii is estimated to have 20 new INNS established per year which is one every 18 days. In 2007 the Minister for Biodiversity in the UK stated that invasive non-native species cost the British economy approximately 2 billion per year. The contribution of non-native species to the UK economy means there is a trade off between economic and ecological factors. The Environment Agency spends 1.5 million per annum on staff and project costs for controlling invasive non-native species. The polluter pays principle is frequently inoperable, as it is often it is not clear who the polluter is. See

4 Markets, such as agriculture, can solve the problem through cost sharing or insurance, although this is difficult to administer with diversified farming or pests that affect multiple crops. Economic impacts of invasive non-native species include: altering ecosystem services such as causing riverbank erosion and flooding and reducing levels of biodiversity; inhibiting water body access through plants forming dense stands blocking access for river users; affecting land developments causing human health problems Control and eradication programmes Some examples of invasive species control and eradication programmes demonstrate the scale of the problem and the Grey squirrels, introduced to GB in 1876, now number more than 3 million. The decline of the native red squirrel population (now less than 120,000) has been attributed to their spread. In some areas half of the grey squirrel population has been exposed to, and may be carrying, the squirrelpox virus. The virus appears to be a minor disease to grey squirrels but has a mortality rate of 99% in reds. The transmission of the virus is being investigated: it may be spread directly or may survive in the environment and be transferred via branches or nest sites that both species use. Grey squirrels also have negative impacts on forestry and woodlands by damaging trees through bark stripping. A survey of public opinion showed support for the control of grey squirrel populations for economic and ecological reasons. A nationwide eradication programme was attempted in the 1950s, but their numbers and distribution now make this impractical. At present, live trapping is the most effective method of control over large areas but it is expensive. The development and subsequent use of an immunocontraceptive for control of greys is being investigated but is still around 6-8 years off. Use of a vaccine against the virus may help to conserve red squirrels (although development is at least five years from completion and rigorous field testing will be required). See

5 Recent control programmes include the eradication of mink from the Hebridean Islands. This programme had high levels of public support due to their impact on economic activities such as bird watching, game shooting and fisheries by predating fish and the chicks or eggs of ground nesting birds. There can be ethical objections to eradication programmes especially when the species are present due to humans. The GB-wide ruddy duck eradication programme has met a mixed response although the public are generally positive when they understand the reasons for eradication. New legislation to ease difficulties with species eradication programmes such as giving compulsory access to private land has now been brought in - Infrastructure Act 2015 and the Anti-social Behaviour, Crime and Policing Act 2014 allows councils, statutory authorities and communities in the UK to force landowners to eradicate invasive species if they are causing a nuisance. Global Case Study: World s First Bio Invasion Chronic Emergency Lake Victoria Nile Perch and Water hyacinth 2 nd largest lake in the world 500 species of cichlids (single genus) classed as trash fish by fishermen but most are endemic to the lake. Several larger tilapia species were overfished Between 1954 to 1962 Europeans introduced Nile Perch By 1981 it was estimated that the lake contained 17,000 tons By ,400 tons 200 endemic cichlid species became extinct

6 Meanwhile... Smoked fish led to deforestation which led to erosion which led to nitrification of the lake which led to algal blooms which led to reduced oxygen (eutrophication) and ultimately dead fish. Cichlids couldn t breed but invertebrates could, including mosquitoes (malaria) and snails (bilharzias). The perch population exploded again. Water Hyacinth arrived about 1990 This species thrived in the eutrophic water with no other herbivorous fish, resulting in a population explosion By 1996 it was present on 95% of shorelines which led to no breeding fish It blocked harbours preventing fishing The high transpiration rate caused low water and O2 levels It blocked pumps e.g. water to Kampala, Hydro electric plants There was an increase in snails and mosquitoes which resulted in an increase of human diseases such as malaria and bilharzia

7 Water hyacinth choking the lakeside Water hyacinth The Future Over 30 million people live around the lake and depend on it. It s demise as a vibrant ecosystem is being felt by the local people. A major cooperative effort among all three lakeside countries -Uganda, Kenya, and Tanzania-was

8 recently launched the Lake Victoria Environmental Management Program - which will focus on water quality, land use management, restoration of indigenous food fish, control of Nile perch and water hyacinth, and community-based enforcement. Successful methods developed in pilot zones around the lake during previous years will then be applied to larger areas. Issues include: Herbicides some countries don t want to use them. Natural control not popular! Political tensions three countries border the lake Uganda, Tanzania and Kenya. Nile perch too big and oily for villagers to dry in the sun, people not sure how to deal with it in the heat so being left to rot. External investment has brought in processing plants but locals cannot afford to buy it. Local protein starvation with 200,000 tons being exported! Superstition Nile Perch are now cannibalistic and people are reluctant to catch them. Funding World Bank has been funding the project. Latest phase cost US$30 million. Further Reading Read about key results of the Lake Victoria project: