Non-native marine hitchhikers are bad news for UK shore dwellers
Crabs with hairy pincers, constantly copulating limpets and skeleton shrimps are among some of the strange sights you may see lurking on our shoreline.
Download our guide here: Marine Non-native Species ID Guide
The coastal waters of the UK may seem very inviting as we head to the seaside for our holidays, but few will be aware of the aliens amongst them – visitors from beyond.
Slipper limpets, veined rapa whelks and Chinese mitten crabs are among the alien invaders that are competing for space along our shores with our home grown marine dwellers – and these interlopers just keep on coming!
Arriving in UK waters as illegal immigrants aboard commercial vessels, plastic debris and other drifting materials, the sharp growth in numbers of these alien marine species has led MCS to join forces with the Marine Life Information Network (MarLIN) to raise awareness of these non-natives, and urge people to help identify them.
The names of these invading plants and animals may sound very exotic – wakame, wireweed, Japanese skeleton shrimp and Pacific oyster to name but a few. However, Emma Snowden from MCS, says their impact on our own habitats, species and ecosystems can be invasive and destructive. “Alien marine species are dwelling in the space that our native species would usually inhabit, meaning UK wildlife like crabs and shrimps are, quite simply, being squeezed out.”
One of the aliens, wireweed, a type of brown seaweed, is rampant in some parts of the UK as it finds the sea conditions to its liking. It takes over rockpools and the seabed, meaning our own native seaweeds have less space to grow, and boat users report that it can be a nuisance at sea when it tangles around propellers.
Emma says the sex- changing slipper limpet, a type of sea snail, is another alien that is changing the nature of our seabed along the south coast: “Slipper limpets reproduce at an incredible rate, copulating in long chains and smothering the seabed as their dead shells pile up. In some places, like Brighton beach, you only have to scoop up a handful of pebbles to see how many slipper limpet shells are being washed up there – they are totally rampant!”
The increase in invasive species is not just of concern for conservationists, there could be financial implications too. The Chinese mitten crab, with its dense mat of hair on its claws, can grow to the size of a dinner plate. It burrows in muddy estuaries and weakens banks often built up to create flood defences by local authorities and government agencies.
Emma says any information that can be gathered about these foreign invaders will help build up a picture of where they are and the sort of disruption we can expect to our own indigenous species; “We know they are here but what we need to establish is the full extent of the damage that they can cause and how we can combat it.”
Guy Baker, Communications Officer at the Marine Biological Association says the damage from invaders is being done on two fronts: “The threats to our marine environment are increasing and this matters not simply because of losses of native biodiversity, but also because biological invasions are potentially damaging to the industries that depend on healthy and productive inshore waters. Working together we can reach a wider audience and gather more information on marine invasive non-native species.”
If you would like to help track down these alien species then you can download the Marine Non-native Species ID Guide then report your sightings via the MarLIN website www.marlin.ac.uk/rml or phone 01752 633291.