Invasive Species in IrelandIdentification Cards

What are they?

Non-native species are species that have been introduced, either intentionally or unintentionally, outside their natural range. Many of these species live in harmony with our native species causing no adverse impacts. A few non-native species though become what is known as ‘invasive’ as they thrive in our habitats and out-compete our native flora and fauna.

Invasive Species in IrelandIdentification Cards

How can you help?

Inspect: all equipment that has been in a waterbody or terrestrial site for attached vegetation.

Remove: any adhering plant, soil or animal material before leaving a site.

Clean: power hose all equipment. Use hot water (> 60 degrees centigrade where possible.).

Dispose: of all plant material and animal material appropriately.

Report: Report any sightings on www.invasivespeciesireland.com

Invasive Species in IrelandIdentification Cards

Nuttall’s Pondweed Elodea nutallii

Photograph by Joe Caffrey

Key features

Leaves in whorls of 3.•Leaves often recurved.•Gradually narrows to tip.•Often found in still and slow flowing •water.Spread by fragments.•

Impacts

Clogs waterbodies.•Excludes native species.•Impacts on water based recreational •activities.Prevents free casting.•Tangles in engine propellers •inhibiting free movement.

New Zealand pigmyweed Crassula helmsii

Photograph by John Early

Key features

Also known as ‘Australian Swamp •stonecrop’.Small white flower.•Spread by fragments.•

Impacts

Clogs waterbodies.•Excludes native species.•Impacts on water based recreational •activities.Prevents free casting.•Tangles in engine propellers •inhibiting free movement.

Photograph by Joe Caffrey

Parrots feather Myriophyllum aquaticum

Key features

Small feather like side shoots on stem.•Red main stem commonly.•Spread by fragments.•

Impacts

Clogs waterbodies.•Excludes native species.•Impacts on water based recreational •activities.Prevents free casting.•Tangles in engine propellers •inhibiting free movement.

Photograph by Joe Caffrey

Curly Leaved Waterweed Lagarosiphon major

Key features

Leaves in spiral arrangement not •whorled.Grows in water up to 5 metres deep.•Spread by fragments.•

Impacts

Clogs waterbodies.•Excludes native species.•Impacts on water based recreational •activities.Prevents free casting.•Tangles in engine propellers •inhibiting free movement.

Photograph by Joe Caffrey

Fringed waterlily Nymphoides peltata

Key features

Small yellow flower with 5 petals.•Fringe on edge of flower leaves.•Small rounded lily pad (10-15cm max).•Thrives in shallow water (<1.5 metres •deep).Grows around the edge of lakes and •ponds commonly.Spread by fragments.•

Impacts

Clogs waterbodies.•Excludes native species.•Impacts on water based recreational •activities.Prevents free casting.•Tangles in engine propellers inhibiting •free movement.

Photograph by Joe Caffrey

Water fern Azolla filiculoides

Key features

Small fern like leaves.•Green in spring / summer.•Red colour in Autumn / winter.•

Impacts

Prevents oxygen transfer from air to •water.Can result in low oxygen levels •resulting in fish kills.Excludes native species.•Can be mistaken for grass.•

Photograph by John Early

Floating Pennywort Hydrocotyle ranunculoides

Key features

Dense floating mat.•Thrives in shallow still flowing water.•Rooted in water less than 1 metre in •depth.Kidney shaped leaves.•Distinctive ‘V’ indentation in leaf.•Leaves are typically 2 to 8 cm in •diameter.Spread by fragments.•

Impacts

Clogs water bodies.•Excludes native species.•Impacts on water based recreational •activities.Prevents free casting.•Tangles in engine propellers •inhibiting free movement.

Photograph by Joe Caffrey

Himalayan balsam Impatiens glandulifera

Key features

Grows up to 3 metres in height.•Purplish to pale pink flowers in June - •August.Hanging seed pods.•Hexagonal hollow stems.•Alternative leaves.•Serrated edge to leaves.•Dark green leaves.•Spread by seed.•

Impacts

Excludes native species.•Leaves river banks exposed to erosion •in winter.Subsequent potential sediment •impact on fish spawning areas.Attracts pollinating insects away from •native species.

Photograph by Tom Ennis

Grey Squirrel Sciurus carolinensis

Key features

Grey coat in spring – summer months.•In winter the coat can have a •brownish colouration.

Impacts

Out-competes red squirrels for food.•Carries the Parapox virus to which red •squirrels are not immune to.Damages trees.•

Photograph by Joe Caffrey

Japanese knotweed Fallopia japonica

Key features

Grows up to 3 metres in height.•Yellow / cream flowers in late summer.•Hollow stem / Red stem in summer.•Brown stem in winter.•Extensive rhizome system (roots).•Orange centred rhizome.•Leaves arranged in a zigzag pattern.•Spread entirely via plant and rhizome •fragments.

Impacts

Excludes native species.•Dies back in winter leaving River •banks vulnerable to erosion.Subsequent potential sediment •impact on fish spawning areas.In cases it can damage building •foundations.Collects litter in urban areas.•Can damage tarmac by growing •through it.

Photograph by Joe Caffrey

Giant Hogweed Heracleum mantegazzianum

Key features

Often grows up to 3-5 metres in •height / Leaves expand up to 1.5 metres in width.Large flower heads.•Large seeds in clusters.•Purple stems with a fine hair like •appearance.Hollow stems / Spread by seeds.•

Impacts

Harmful to humans• due to toxic sap making the skin sensitive to UV light.Can lead to the closure of public •amenity areas.Excludes native species.•Dies back in winter leaving river •banks vulnerable to erosion.Subsequent potential sediment •impact on fish spawning areas.Reports suggesting its leaves can be •harmful to young wildfowl.

Photograph by Paul McLoone

Dace Leuciscus leuciscus

Key features

Interior mouth – top lip protruding•Concave dorsal fin•Concave anal fin.•Deep fork in caudal fin.•Yellow (not red) eyes•Slim silver/green body•

Impacts

Competes with native fish species •for habitat, food and spawning substrates.

Photograph by John Coyne

Chub Leuciscus cephalus

Key features

Inferior mouth – top lip protruding.•Convex dorsal fin.•Convex anal fin.•Deep fork in caudal fin.•Inhibits rivers with moderate flow, but •can also be found in lakes.

Impacts

Feeds on aquatic plants and •invertebrates when young. As they mature they feed more selectively on larger prey, including young fish.Competes with native fish species for •habitat and food.

Photograph by NIEA

Zebra Mussel Dreissena polymorpha

Key features

Rarely exceeds 30mm in length.•Forms dense clusters on hard surfaces.•Found in freshwater and brackish •waters / Stripped shell.Spreads naturally within a waterbody •once established / Moves between waterbodies on boat hulls, fishing equipment and ballast water.

Impacts

They • do not make the water cleaner.They filter much of the plankton that •juvenile fish depend upon.Block out-pipes and clogg engines •and cooling systems.Block intake pipes / Form dense •clusters on native mussels.Mask the natural response to •eutrophication.Can result in toxic algal blooms •impacting on drinking water.

Photograph by Alan Cullagh

Chinese mitten crab Eriocheir sinenisis

Key features

Hair like covering (mitten) on its •claws.White tipped claws.•4 pointed carapace on each side.•The only freshwater crab species •found in Ireland.

Impacts

Burrows into banks leading to their •collapse in cases.Carries lung fluke parasite which is •harmful to humans if ate.Feeds on invertebrates and fish.•Where present in large numbers they •can impact on native fish populations.

Photograph by John Early

Giant Rhubarb Gunnera tinctoria

Key features

Resembles a larger version of the •common rhubarb.Grows up to 2-3 metres in height.•Hairy appearance on the leaves.•Spreads via underground rhizomes •(roots).

Impacts

Excludes native species by blocking •out the light.In the winter when it dies back it •leaves slopes vulnerable to erosion.Subsequent potential sediment •impact on fish spawning areas.

Photograph by Richard Weyl

Hottentot Fig Carpobrotus edulis

Key features

Waxy long stems which are triangular •in shape.Found in coastal areas.•Bright Pink or yellow flowers.•Spreads by seed and from •segmentation.

Impacts

Excludes native species.•Covers geological rock features.•Covers potential bird nesting areas in •coastal areas.

Photograph by Tom Ennis

Ruddy Duck Oxyura jamaicensis

Key features

Blue bill on male.•Upright tail.•White cheeks on the male.•Chestnut plumage.•

Impacts

Male Ruddy ducks out-compete male •white-headed ducks.They mate with the female white •headed ducks producing hybrids.They compete for nesting space and •food.Interbreeding may result in the •eventual extinction of the white headed duck.

Photograph by Mark Hammond

Common cord grass Spartina anglica

Key features

Robust grass with shoots 0.4m - 1.3m.•Spread by both seed and vegetatively.•Yellowish green in Spring / summer.•Light brown in Autumn / winter.•

Impacts

Produces dense monoswards •slowing the movement of water and increasing the rate of silt deposition.Raises the general level of the marsh.•Excludes native species.•Reduces the available food resources •for wildfowl and wading birds.Reduces the area of eel-grass beds •and invertebrates.

Photograph by M.D. Guiry / www.algaebase.org

Wire weed Sargassum muticum

Key features

Large brown alga / Air bladders.•Occurs from intertidal to subtidal •range of substrates.Also occurs on hard rock surfaces and •Eel grass beds.Grows in dense mats up to 16 metres •in length.Spreads both sexually and via floating •fragments.

Impacts

Smoothers native species and Eel • grass beds.

Reduces the light for under story •species / Dampens water flow.Increases sedimentation.•Reduces ambient nutrient •concentrations available for native species / Drifts and clogs marinas.Clogs intake pipes of boats.•

Photograph by Julia Nunn

Didemnum spp.

Key features

Colonial sea squirt.•Grows in long candle wax like •colonies that hang from hard surfaces such as docks, lines and ship hulls.It can also form undulating mats that •cover and encrust rock seabeds.

Impacts

It is spread by larvae and •fragmentation. It is mainly transported on the hulls of boats, fishing equipment and ballast water.Threatens the aquaculture industry.•Smoothers bivalves such as mussels, •scallops, oysters and fish spawning grounds.Smoothers seaweeds and sponges.•

Photograph by Lin Baldock, Ulster Museum

Leathery Sea Squirt Styela clava

Key features

Marine species- Found in shallow •seawater.Can live in water as deep as 25 •metres.Long club shaped body on a tough •stalk.Tough surface which is leathery, •rumpled and nobly.Can be brownish-white, yellowish-•brown or reddish-brown.Each individual has it’s own stalk.•Adheres separately.•

Impacts

Competition for food.•Competition for space.•Fouling ships and other structures.•Fouling native oyster beds.•Fouling aquaculture species •(e.g. mussels & oysters)

Photograph by Judith Oakleywww.oakleyintertidal.co.uk

Pacific Oyster Crassostrea gigas

Key features

The shell is extremely variable in •shape and can grow up to 18cm in length. The colour is variable but usually •off-white to yellow or bluish grey. Often extremely rough and sharp. •Can be found in intertidal and •subtidal zones.

Impacts

Can settle in dense colonies of several •thousand per square meter. Excludes other intertidal species •where it does. Can impact on bird species by •excluding their food source. Can impact on tourism and •recreational activities by covering shorelines and beaches in razor sharp shells.

Photograph by Trevor BanhamForestry Commission England

Muntjac Deer Muntiacus reevesi

Key features

Small (approx 50cms tall to the •shoulder) Brown in summer.•Grey Brown in winter.•Short antlers (up to 10cm).•Large facial glands below the eyes.•Visible upper canines in bucks (males).•Pronounced black lines running along •head / Barking sound made – the ‘Barking’ deer.Peak activity at dawn or dusk.•

Impacts

May act as a reservoir for various •animal diseases.Damage to crops.•Damage to under storey species and •rare woodland plants /Damage to new commercial forestry plantations.Impacts on woodland management •practices.

Produced by John Early (NIEA)

Designed by Gillian Maguire (NIEA)