Taxonomy
Gammarus tigrinus
Distribution
Status
Conservation status
Not Assessed
Legal status
Listed as a schedule 9 species under Articles 15 & 15A of the Wildlife Order (Northern Ireland) 1985 (Article 15A not yet enacted).
First reported in the wild
1931
Invasiveness
Invasive species - risk of Medium Impact
Irish status
Established
Introduction pathways - 1
Transport Stowaway
Introduction pathways subclass - 1
Ship/boat ballast water
Invasive score
16
NAPRA Ireland risk assessed
No
Species Biology
Identification
Freshwater shrimp, generally less than 15mm long with black markings, smaller than Gammarus pulex. Identification to species difficult.
Ecology
Effects of G. tigrinus are difficult to assess due to intra-guild competition between it and native and non-native amphipods. Male G. d. celticus and G. pulex prey more frequently on moulted female G. tigrinus than male G. tigrinus do of females of the other two species but G. tigrinus preyed on female G. d. celticus significantly more frequently than on female G. pulex (Dick, 1996). The effects on native communities would be expected to be similar to those of G. pulex, lowering native benthic invertebrate abundance, biomass, species richness and species diversity (Kelly & Dick, 2005), but moderated by the presence of other Gammarus species.
Habitat
Inland surface waters
Reproduction
As with a number of Amphipod species, they engage in pre-copulatory mate guarding, where the male guards a female by carrying her beneath him waiting for her to moult to allow mating.
Pathway and vector description
Species was first described in 1931 but may have arrived from North America in ballast water during the World War 1 (Hynes in Costello, 1993). Dispersal in Ireland appears to be by natural means.
Mechanism of impact
Competition, Predation
Broad environment
Marine
Habitat description
Freshwater species, found in rivers, lakes and streams.
Species group
Invertebrate
Native region
North America
Similar species
Distribution
World distribution(GBIF)
Irish distribution
Established - Widespread & Locally abundant (Minchin et al., 2013).
Native distribution
Native to North America.
Temporal change
Date of first record category
Unknown
Fifty year date category
1901-1950
Records submitted to Data Centre in 2024
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How can you help
Report any sightings to the National Biodiversity Data Centre.
References
Publications
Minchin, D, (2007). A checklist of alien and cryptogenic aquatic species in Ireland. Aquatic Invasions, 2(4), 341-366. Costello, M. J. (1993). Biogeography of alien amphipods occurring in Ireland, and interactions with native species. Crustaceana, 65(3), 287-299. Minchin, D., Jazdzewski, K. & Anderson, R. (2013) Further range expansion of two North American amphipods in Ireland. Irish Naturalist's Journal, 32(1). Dick, J. T. (1996). Post-invasion amphipod communities of Lough Neagh, Northern Ireland: influences of habitat selection and mutual predation. Journal of Animal Ecology, 756-767. Kelly, D. W., & Dick, J. T. (2005). Introduction of the non-indigenous amphipod Gammarus pulex alters population dynamics and diet of juvenile trout Salmo trutta. Freshwater Biology, 50(1), 127-140.