This week is the UK’s Invasive Species Week which aims to raise awareness of the issues that invasive species can cause and of the work being done to prevent their spread and reduce impacts.
So what is an invasive non-native species and why do we worry about them? Non-native species (which can also be called alien or introduced species!) are animals and plants which have been moved to new locations outside their native range. The majority of these don’t cause any problems but a few can have drastic consequences in their new environments, harming other wildlife or causing problems for the people that live and work there – these are known as invasive non-native species (or INNS).
Non-native species are moved by humans – either intentionally such as for food or as pets, or accidentally as hitchhikers on boats, equipment or with other organisms. For instance, people think the invasive wireweed Sargassum muticum (header photo) was introduced to Europe when it was used as packing material for oysters being moved from the USA to France in the 1960s. It’s now widespread across a lot of the coasts in the south of the UK, and a species we’re keen for folks to keep an eye out for on Shetland’s coasts.
Non-native species can be introduced into any type of habitats – on land, into rivers, or into seas. And species that are part of our native wildlife here cause problems in other parts of the world. For instance our native green shore crab (Carcinus maenas) which is a normal shoreline species in the UK has competed with native crabs after its introduction to the USA and is considered a pest. It’s always fun chatting to other non-native species researchers from across the world, as we’re often studying the same species but consider each other’s native species the problem – it gets a bit confusing!
The environmental problems caused by invasive species can range from impacting individual native species to completely changing the structure of habitats. Where invasive species can cause the most environmental damage is to places where the native species do not have any natural defenses. One example of this is the introduction of predators such as rats or mink to islands with nesting birds which naturally have no land predators. The lack of familiarity with novel species can also cause problems for people as well. For instance, caterpillars of the oak processionary moth which was introduced to England in 2005 can cause rashes and breathing problems due to tiny toxic hairs if people disturb them.
Invasive species can also cause costly problems for people by affecting industries, for example the introduction of sea-squirts Styela clava and Didemnum vexillum have caused problems for aquaculture by fouling gear and increasing cleaning costs. In the Black Sea, the introduction of the invasive ctenophore Mnemiopsis leidyi (a small jellyfish-type animal) contributed to the decline of commercial fish stocks in the 1990s by competing with fish for food and eating small fish larvae. It’s hard to predict which species will cause problems so it’s best to take a precautionary approach and try not to move species around.
It can be very hard to control a species once it has arrived and begun to spread. The best idea is to stop new species from ever arriving, and to be especially cautious when we want to protect vulnerable habitats or where people’s livelihoods might be affected. We use the term Biosecurity for actions taken to protect places from the introduction of new non-native diseases, plants or animals. This encompasses a wide range of activities and behaviours we can take personally or which are built into how businesses operate.
As individuals we can do things like make sure our boots are clean of mud and seeds before travelling away and back from holiday, cleaning the gear we use to paddleboard, swim or kayak, or stowing food securely and checking for rats or mice when travelling on boats to smaller islands.
Coming up this week
This week we’ll be sharing some information about what non-natives are found in Shetland, and some of the research and work going on to prevent spread into and around the Shetland Islands. We’ll be posting a blog a day and sharing information and resources on social media, so follow along!
Tuesday – Marine non-native species monitoring at UHI Shetland
Wednesday – Introduced plants in Shetland – Guest blog by Paul Harvey, Shetland Amenity Trust
Thursday – Non-native mammals in Shetland, and a flatworm all the way from New Zealand – Guest blog by Paul Harvey, Shetland Amenity Trust
Friday – Keeping an eye out for rodents on Mousa – Guest blog by Holly Paget-Brown, Biosecurity for LIFE
If you want more information on invasive species in the rest of the UK, have a look at the GB Non-native Species Secretariat website!