Habitat: Brackish ecosystems with rock sediments. Hemimysis can be found on the benthos during the day and in the pelagic zone at night where it can be observed aggregated in swarms.
Description: Hemimysis is a mysid. It is shrimp like in appearance with a curved body, long thin antennae and large bulbous eyes. Adults range in size from 5.5-12.5mm and are deep red to ivory yellow in colour.
Origin and Distribution: Originates from The Black and Caspian Seas. Now found in Russia, Lithuania, Ukraine, Moldova, the Baltic Sea, Poland, Finland, Germany, Holland, Belgium, Scandinavia and England.
Impacts: Hemimysis is likely to alter the dynamics of the invaded ecosystem as a result of predation on macroinvertebrates and competition with native invertebrate species for resources. These impacts may in turn have knock-on effects further up the food chain.
Where is it found in Ireland? Recently (2008) reported in Ireland from Lough Derg and Lough Rea
See the National Invasive Species Database for more information on the distribution of this species in Ireland.
How did it get here? The pathway of introduction for Hemimysis to the Island of Ireland is unknown. Any of the following pathways provide a feasible means of introduction: bilge water from leisure craft, water from stocking of imported fish or the aquarium trade; either as live food or associated with aquatic plant imports.
Do not move water from one waterbody to another include bilge water, ballast water, boat toilet water and water in bait boxes.
Clean all parts of equipment, boats and trailer that come into contact with the water.
Remove any visible plant, fish, animal material and mud from equipment.
Do not allow rinse water to return to the environment. Many organisms can remain viable even in small (sometimes microscopic) quantities.