Monitoring marine non-natives at UHI Shetland

Today we’re exploring the species that get moved around across oceans and continents to be introduced to our coastal seas. As the world becomes increasingly connected by trade, there are more opportunities for species to hitch-hike attached to boats or within ballast water, or be accidentally transported for aquaculture, released from aquariums or as part of live food imports.

The species we find in the UK which are commonly introduced are those which are good at living or growing in man-made environments – i.e. they can be found attached to hard structures like boats, piers or pontoons.

Free-swimming species such as fish and jellyfish have caused big impacts in other parts of the world, introduced when canals like the Suez Canal connect two previously isolated water bodies. Hundreds of species have moved from the Red Sea to the Mediterranean along this pathway.

Marine species can be transported vast distances and no place is remote enough to escape the impact – there is increasing worry about the potential introduction of novel species to the Arctic and Antarctica on visiting boats. These environments could be especially vulnerable to novel species due to their isolation and unique habitats.

Becky (left) monitoring non-native species on a research trip to Svalbard in the arctic with colleagues from Wageningen University & Research (photo by Hans Verdaat).

Monitoring in Shetland

Rachel and Kate at UHI Shetland look at the fouling species in a Shetland marina

At UHI Shetland, we monitor key sites to detect the arrival of new species and track the spread of marine non-natives already present in Shetland. We do this every year by setting out monitoring panels in marinas and harbours as these environments are most at risk. Native and non-native fouling species that like to grow on hard structures settle on these plates. We remove the plates after 3 months or so and identify the different species. This gives us an easy way to look at what’s living under the surface without having to go for a swim.

We have been carrying out this monitoring over the last decade. There are records of 12 marine non-native species in Shetland which is far fewer than are found in the south of the UK, or in mainland Scotland, potentially as a result of the colder waters around Shetland.

However, we still have had a few introductions which have the potential to cause problems. For example, the orange ripple bryozoan, a type of animal where lots of individuals housed in box-like outer skeletons (zooids) which form a larger colony. It was originally from the northwest Pacific but has been found in Scotland since 2010. It is used to cold-waters and can come to dominate fouling communities that grow on hard structures, taking over space from native species.

Causing problems

The reason why we’re so keen to detect species quickly once they arrive is that it’s much harder to control the impact they have once they have become established and started to spread. And while many non-natives don’t cause any problems, others can harm both the environment and people.

Invasive species can cause problems for marine industries, for instance by growing on structures such as piers or slipways, by getting tangled in boat propellors, or by spreading disease or growing on aquaculture species. They can also change how we interact with the sea. The introduction of a jellyfish species Rhopilema nomadica to the Mediterranean meant more people were being stung on beaches, resulting in millions lost in reduced visitor numbers for the tourism industry.

Some changes might not have such big economic consequences, but can still change how people interact with the environment. The invasive wireweed Sargassum muticum has become the dominant species in rockpools in some areas of the south of England and on the Isle of Man, and because it floats and is very stringy and tough it means people are more likely to trip and fall over when exploring rockpools as it gets tangled around your legs.

The invasive wireweed Sargassum muticum dominating a rock pool by cutting out light for other species in the Isle of Man. This is one of the species we’re on the lookout for in Shetland.

Keeping an eye out

It’s important that we detect new arrivals quickly and it is challenging to monitor species over the long coastline so we also rely on members of the public looking out for key species or noticing unusual species while they are out and about. Species we are most concerned about include wireweed, Sargassum muticum, and the Carpet seasquirt, Didemnum vexillum. We have an identification guide that sets out key species we’re interested in hearing about if you find them on Shetland. Any records can be sent via the shetlandcommunitywildlife@outlook.org email address, with a note of where exactly you found something, a description and a photo.

Preventing the spread of invasive plants and animals is something we can all help with. If you are moving equipment or boats, paddleboards or snorkel gear between water bodies, and especially on/off Shetland you should follow “Check, Clean, Dry”. The GB Non-native Species Secretariat website has a lot of information on biosecurity in the UK, including information specific to the marine environment for industry and individuals.

Download our INNS guide here

Anyone interested in learning more about non-native species is welcome to come and see what we do at one of our events in Scalloway or Burravoe this week, and we’ll be running further training in the summer for anyone who wants to get more actively involved in monitoring. Let us know if you’d be interested in this by dropping us an email!

You can find out more information about the work we do on marine non-natives on the UHI Shetland website – click here

Welcome to INNS Week!

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!

Image by Sara Redstone, GBNNSS – Oak processionary moth caterpillars devouring an oak tree.

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.

The invasive sea-squirt Styela clava fouling aquaculture gear in Canada.

Biosecurity

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!