Check, clean, drain, dry – keeping the waters of the Brecon Beacons National Park free from invasive aquatic species

Every water user could be inadvertently carrying unwanted passengers. Non-native, invasive species put the lakes, canals, rivers and reservoirs of Wales are at risk. They can have a huge impact on Welsh freshwater species and cause nuisance, damage and even injury to wildlife, anglers and recreational water users. So, please watch out for stowaways!

Here are three of the least wanted.

Zebra mussel (Dreissena polymorpha)

A bivalve that lives in fresh or slightly salty waters. It has brownish-yellowish triangular shells measuring up to 50mm with dark and light coloured zigzag banding. It forms large colonies on lake beds and hard structures such as inflows, outflows, propellers, steering gear, jetty pylons, buoy chains and boat hulls. In the United States, it has caused millions of dollars of damage. The sharp shell edges have been known to cause nasty injuries to water users.

Killer shrimp  (Dikerogammarus villosus)

This freshwater shrimp is similar to our native freshwater shrimps but can grow much bigger, up to 30mm. It is a voracious predator, hence its rather dramatic name. It has spread across much of mainland Europe where its presence upsets natural food chains and native populations of freshwater species.

Asiatic clam (Corbicula fluminea)

A bivalve with a tan to brown, ridged globular shell. It can occur in large numbers in sediments and is usually less than 30mm in size. It is a self-fertilising hermaphrodite, so a single clam can develop into a significant population. Like the killer shrimp, it has a significant impact on natural ecosystems.

All three of these species are present in South Wales and perhaps elsewhere within the UK. The larval stage of each species is tiny (<1mm) and can survive in any damp kit or tiny amounts of trapped water. When boats, canoes, bait buckets, wetsuits, life vests and boat trailers are used on different sites, there is a risk of accidently spreading these unwanted species.

What to do

A few simple precautions can significantly reduce the risks.

  • CHECK for any information on non-native species at water recreation sites and follow the instructions
  • CLEAN your gear, making sure that you remove any plants, animals, mud and muck from any gear that has been in contact with water, including waders, boat trailers and vehicles
  • DRAIN all water from bilges, ballast tanks or anywhere water can collect and flush with dilute bleach solution waiting for one hour before draining and rinsing, making sure this process occurs well away from any watercourses
  • DRY your kit thoroughly in a well ventilated and sunlit place, or sponge down with dilute bleach solution, ensuring that washings do not enter watercourses

Following these steps will help prevent the spread of these species. With responsible water users on board, we can keep the waters of the Brecon Beacons free from unwanted visitors.