Demon shrimp

Dikerogammarus haemobaphes is a species of amphipod shrimp, native to the Ponto Caspian region. The species has spread across much of eastern and western Europe, establishing large self sustaining populations in many freshwater rivers and lakes. In 2012, it was discovered in the UK, in the River Severn and has continued to spread throughout GB, often associated along with the spread of zebra mussels. It is likely that zebra mussels in GB may have provided important habitats in many locations, and may be especially important in facilitating spread through the Midland canal system. Zebra mussels are distributed broadly through GB from East Anglia to Cardiff Bay and from West Sussex to the Forth & Clyde Canal in Scotland (Aldridge, 2010). It was first reported and confirmed in Ireland on 30th September 2025 as part of annual monitoring of the relative abundance of the quagga and the zebra mussel in lower Lough Derg. It was also common in samples taken during the following day.  No specific studies have been reported on the vectors and pathways for D. haemobaphes spread, but downstream drift is likely to generate the fastest dispersal within a catchment (van Riel et al., 2006). The discovery of specimens in two canals adjacent to the River Severn, separated by many locks, suggests it may be distributed with boat traffic. The association of the species with macrophytic vegetation (Musko, 1990) suggests that overland transport may be possible on contaminated outboard engines and fishing gear. The spread of previous invasive species in the Shannon - Erne system has proved to be rapid, eventually arriving in Upper and Lower Lough Erne water bodies. It is a very busy recreational watercraft pathway with over 36,000 lock passages in 2024.