Invasion
Invasion Description
1st Record: Latvia/Gulf of Riga (2003, Kotta 2005) Kotta J. 2005. Gammarus tigrinus arrived in the Gulf of Riga in July 2003. In: ICES Report of Benthos Ecology Working Group, 19-22 April 2005, Copenhagen, Denmark: p.14.; Estonia/Ko˜iguste Bay, Gulf of Riga (Orav-Kotta et al. 2008)
Geographic Extent
Ainaži, RanduEstonia/Ko˜guste Bay, Gulf of Riga (Orav-Kotta et al. 2008; Janes et al. 2013; Kuprijanov et al. 2015); Estonia/Gulf of Riga (Herkull et al. 2009); Latvia/Gulf of Riga (2003, Kotta 2005) Kotta J. 2005. Gammarus tigrinus arrived in the Gulf of Riga in July 2003. In: ICES Report of Benthos Ecology Working Group, 19-22 April 2005, Copenhagen, Denmark: p.14.; Latvia/Parnu Bay (1/14/2012, Strode et al. 2013); Ainai, Randu/Latvia/Gulf of Riga (1/10/2011, Strode et al. 2013); Jurmala/Latvia/Gulf of Riga (6/15/2011, Strode et al. 2013); Ragciems/Latvia/Gulf of Riga (4/6/2012, Strode et al. 2013)
Vectors
| Level | Vector |
|---|---|
| Alternate | Canal |
| Alternate | Ballast Water |
| Alternate | Natural Dispersal |
Regional Impacts
| Ecological Impact | Trophic Cascade | |
| Experiments suggest that Gammarus tigrinus has had indirect effects on the native amphipod G. salinus in Baltic waters, by developing large populations in pebble habitats, which attract the predatory fish Gasterosteus aculeatus (Three-Spined Stickleback). The introduced amphipod has a higher reproductive rate, which compensates for increased predation, but the native species decreases in abundance, because of the intensified predation (Kotta et al. 2010). | ||
| Ecological Impact | Competition | |
| Experiments suggest that Gammarus tigrinus competes with the native amphipod G. salinus in pebble habitats in Baltic waters, under predation by predatory fish Gasterosteus aculeatus (Three-spined Stickleback). The introduced amphipod has a higher reproductive rate, which compensates for increased predation, but the native species decreases in abundance, because of the intensified predation (Kotta et al. 2010). The two amphipod species tended to avoid one another, but the presence of G. tigrinus had a greater effect on habitat choice by G. salinus. However, this effect was weak and variable (Kotta et al. 2011). Gammarus tigrinus have greater fecundity than native G. duebeni in Koiguste Bay, Gulf of Riga. The combination of high fecundity and predation on juvenile amphipods favors G. tigrinus (Janes et al. 2015). Gammarus tigrinus displaced the native amphipods (G. salinus, G. oceanicus G. zaddachi) from shallow waters dominated by vascular plants, moving them to deeper areas vegetated with seaweeds (Reisalu et al. 2016). | ||
| Ecological Impact | Predation | |
| Adults of both Gammarus tigrinus and the native G. duebeni both prey on juvenile amphipods of both species. However, G. tigrinus has greater fecundity than G. duebeni in Koiguste Bay, Gulf of Riga. The combination of high fecundity and predation on juvenile amphipods favors G. tigrinus (Janes et al. 2015). | ||