Environmental DNA testing has flagged the possible presence of the invasive amphipod Dikerogammarus villosus ("killer shrimp") in waterways near Penarth, Wales, though physical specimens are needed for confirmation. Regulators have stepped up surveillance and are enforcing biosecurity measures at local lakes, warning that Cosmeston's proximity to other waters raises the risk of further introductions. Invasive species can harm biodiversity and carry large economic costs; authorities urge public cooperation while they investigate and consider control options.
Possible 'Killer Shrimp' DNA Found in Penarth Waters — Officials Warn Risk of Further Spread
Environmental DNA testing has flagged the possible presence of the invasive amphipod Dikerogammarus villosus ("killer shrimp") in waterways near Penarth, Wales, though physical specimens are needed for confirmation. Regulators have stepped up surveillance and are enforcing biosecurity measures at local lakes, warning that Cosmeston's proximity to other waters raises the risk of further introductions. Invasive species can harm biodiversity and carry large economic costs; authorities urge public cooperation while they investigate and consider control options.
11:29 AM, 11/10/2025Environment
DNA tests flag possible arrival of invasive "killer shrimp" near Penarth
Environmental DNA (eDNA) sampling has detected genetic traces of Dikerogammarus villosus, commonly called the "killer shrimp," in waterways around Penarth, Wales. Officials caution that while the DNA signal is concerning, additional testing using physical specimens is required to confirm the species' presence.
The nickname "killer shrimp" refers to this amphipod's strong mandibles and aggressive predatory behaviour. Native to parts of eastern Europe, D. villosus has spread across the continent in recent decades and is known for outcompeting native aquatic invertebrates and altering food webs.
Why this matters
Invasive species can escape the natural checks and balances of their home ranges and, in new habitats, overwhelm native species for food and shelter. This can reduce biodiversity and disrupt ecosystem services such as water purification, fisheries and recreation.
These ecological impacts also carry economic costs. Estimates vary, but invasive species have been linked to global losses worth hundreds of billions of dollars per year, and some analyses put cumulative costs at more than a trillion dollars over several decades.
Broader context and responses
Other crustaceans have also turned up beyond their native ranges: for example, non-native shrimp species have been reported in New Zealand waters, and green crabs have established populations in parts of North America. Some communities have begun to harvest invasive species as food or commercial products as part of control efforts; in the UK, targeted removal of invasive crayfish has been used with mixed success.
"Given the proximity of Cosmeston to other aquatic environments, the risk of further introductions remains high," the Penarth council told WalesOnline. "To mitigate this, the council enforces strict biosecurity protocols for all lake users, including pre- and post-use procedures. These measures were rigorously applied during the recent Aqua Park trial, demonstrating our commitment to preventing further spread."
Authorities say enhanced surveillance, public cooperation with biosecurity steps (for example, cleaning equipment and boats) and rapid follow-up sampling to obtain physical specimens will be essential. Once confirmed, managers will assess whether eradication, containment or long-term control is feasible.
What to do if you visit local waters: clean and dry kit and boats, avoid moving live bait or plants between sites, and report unusual-looking species to local environmental agencies.