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Invasive Species

What are Invasive Alien Species?

Alien species are very much a part of our environment these days.  After centuries of travelling around the world and bringing back (either on purpose or accidentally) plants and animals to Ireland, many species that evolved in other countries are now established in the wild here.  While the majority of these species may not become an issue, there are some that do.  These tend to be referred to as ‘Invasive Alien Species’.  For example, current records show that Meath holds approximately 350 species of alien vascular plant, accounting for around one third of the county’s total vascular plant species, and only a handful of these cause problems. 

What problems do Invasive Alien Species cause?

Alien invasive species can result in many problems, including:

  • Damage to our native biodiversity as a result of competition (eg for food, light, space, pollinating insects), changes to habitats (such as chemical changes to water bodies), carrying of diseases and other factors;
  • Damage to our local economies by impacts on fisheries, tourism (eg by reduced walking access), etc;
  • Damage to our infrastructure, including structural damage to buildings, roads and water treatment infrastructure.

Which are the worst culprits in Meath?

Some of the worst existing and potential culprits in county Meath are Japanese knotweed, Giant hogweed, Zebra mussel and Himalayan balsam.  Information on these and others is provided below.

Japanese knotweed (Fallopia japonica)

Japanese Knotweed in Flower Photograph: W. Woodrow    

Description
Growing to about 3 metres tall in dense cane-like clumps, this species has heart or shield shaped leaves, red and green speckled stems and tiny cream coloured flowers in late summer.

Japanese knotweed was introduced to gardens as a ground cover plant.  It is now widely established in the countryside where it spreads from fragments of rhizomes or the plant itself, or as a result of moving contaminated soil. The plant is particularly easily spread along rivers and roads.  The amount of infrastructure and building work in Ireland in recent years has probably increased its spread along roadsides, building sites and waste disposal sites.

Problems associated with this species include:

  • Loss of biodiversity as native species are shaded out
  • Increased erosion as it stops plant growth beneath it in the summer and dies back in winter leaving bare river banks open to erosion
  • Infrastructure damage since it can grow through tarmac, walls, pipework and even concrete
  • Expensive and time consuming to eradicate

Japanese Knotweed Photograph: W. Woodrow

Where is it in Meath?
Japanese knotweed is widespread in Meath and can be found mainly on roadsides and beside water courses.

What can you do?
Do not cut or flail this plant (since this is likely to spread it).  Do not move soil that may be contaminated by plant fragments or roots.  This species needs to be controlled by chemical treatment  (see Best Practice Management Document link below)

Report all sightings:
To Meath County Council Heritage Officer - 046 9097406
To Invasive Species Ireland database - http://www.invasivespeciesireland.com/sighting/

Download Best Practice Management Document from Invasive Species Ireland to help tackle this species - http://www.invasivespeciesireland.com/downloads/BPM.asp 

Download ‘How to manage Japanese knotweed at home’ leaflet from Invasive Species Ireland - http://www.invasivespeciesireland.com/downloads/education_and_awareness.asp 

 

Giant hogweed (Heracleum mantegazzianum)

Giant Hogweed 2 Photograph: W. Woodrow

Description
This plant can grow to up to around 4 metres tall and can be found mostly along river banks and damp ground.  It was introduced to Ireland as an ornamental plant over a century ago. It has huge leaves that can be around 1.5 metres across and tiny white flowers that are spread like an umbrella at the top of the stem.  

Problems associated with this species include:

  • It is a health hazard! -  The plant produces a sap that can cause extreme blistering to the skin, particularly in the presence of direct sunlight.
  • Loss of biodiversity as native species are shaded out
  • Increased erosion as it stops plant growth beneath it in the summer and dies back in winter leaving bare river banks open to erosion
  • The combination of its large size, associated health hazards and fondness of river banks means that it reduces riverside access where it becomes a problem.

Giant Hogweed Photograph: W. Woodrow

Where is it in Meath?
Giant Hogweed tends to occur mainly along water courses, although it can also be found just on damp ground.  It has been recorded in Meath in the River Boyne / River Nanny area in the east of the county, and the Royal Canal in the south.  It is likely that it exists, unrecorded, in other parts of the county.

What can you do?
Safety first - Don’t touch and keep children away from it.
This species needs to be controlled by chemical treatment (see Best Practice Management Document link below).

Report all sightings:
To Meath County Council Heritage Officer - 046 9097406
To Invasive Species Ireland database - http://www.invasivespeciesireland.com/sighting/ 

Download Best Practice Management Document from Invasive Species Ireland to help tackle this species - http://www.invasivespeciesireland.com/downloads/BPM.asp 

Download ‘How to manage Giant Hogweed at home’ leaflet from Invasive Species Ireland - http://www.invasivespeciesireland.com/downloads/education_and_awareness.asp

 

Zebra mussel (Dreissena polymorpha)

Zebra Mussel 2

Description
This small mussel is a native of the Caspian and Black Seas region and has been in Irish waters for only a little over a decade.  A mainly freshwater species, zebra mussels can spread very quickly in the right conditions and have done in Ireland. They are now found throughout the Shannon and Shannon-Erne catchments, in the Grand Canal and in a total of over 50 lakes across Ireland.  It is also possible that they are now in other catchments such as the Barrow / Nore.

Problems associated with this species include:
Zebra mussels are filter feeders and remove much of the plankton that juvenile fish depend upon and can cause other changes to water habitats. They attach to hard surfaces such as boats, buoys and water intake pipes, where they form reef-like clusters. They can block up water intake pipe, causing many thousands of Euros worth of damage.

Zebra Mussel

Where is it in Meath?
There is limited information on Zebra Mussels in the county, although they are known to occur in Lough Sheelin.  Any sightings of this species should be reported to the contacts below.

What can you do?
The most important thing is to stop it spreading in Ireland by adopting a code of practice:

  • Inspect boat hull, equipment and machinery for adult Zebra Mussels and remove them.
  • Clean boat with hot water and allow it to dry after every trip. If you have removed your boat from Zebra Mussel infested waters, you should allow the boat to dry out for 1 month or steam clean.
  • Remove plant life from the hull, propellers, trailer hitches and all equipment since zebra mussels may be attached to the plants.
  • Dry out or disinfect coarse angling keep-nets that may have been in contact with infected water bodies.

Report all sightings to Central Fisheries Board
Dr. Joe Caffrey - email: joe.caffrey@cfb.ie

Download more information on zebra mussels and how to prevent them spreading at the Central Fisheries Board website - http://www.cfb.ie/Notices/zebramussels.htm and the Invasive Species Ireland website - http://www.invasivespeciesireland.com/mostunwanted/detail.asp?id=34

 

Himalayan balsam (Impatiens glandulifera)

Himalayan Balsam

Description
This is an attractive annual plant that grows up to around 3 metres tall.  It has dark green spear-shaped leaves around 10cm long and pink flowers.  Spread by seed, it has exploding seed pods that spread the seed in the immediate vicinity.  The plant is closely associated with watercourses and damp woodlands, and the seeds are often carried by river to new areas.

This annual plant grows to 3 metres high and is spread exclusively by seed. The seed pods explode when mature, scattering the small seeds up to 7 metres from the parent plant. The plants grow in dense stands along the banks of rivers and effectively suppress any native grasses and herbaceous plants. The balsam dies back in autumn, exposing the now bare bank-sides to erosive winter flows.

Problems associated with this species include:

  • Loss of biodiversity as native species are shaded out
  • Increased erosion as it stops plant growth beneath it in the summer and dies back in winter leaving bare river banks open to erosion
  • Reduced access to riverbanks as it can grow quickly in dense stands across footpaths

Where is it in Meath?
Himalayan balsam is associated with a number of watercourses in Meath and has been recorded in the vicinity of the Boyne and Nanny Rivers and Royal Canal.  It is likely that it also exists elsewhere in the county.

What can you do?
Although a nuisance, this species is not dangerous and is one where properly planned community action can really help.  Groups, and even school children can get involved in balsam ‘pulling’ (see Best Practice Management Document link below)

Report all sightings:
To Meath County Council Heritage Officer - 046 9097406
To Invasive Species Ireland database - http://www.invasivespeciesireland.com/sighting/ 

Download Best Practice Management Document to help tackle this species - http://www.invasivespeciesireland.com/downloads/BPM.asp 

 

Other Species

There are many other species deserving the title of Invasive Alien Species, including:

Aquatic weeds:

  • Curly leaved waterweed (Lagarosiphon major)
  • New Zealand pigmyweed (Crassula helmsii)
  • Nuttall’s pondweed (Elodea nuttallii)
  • Parrot’s feather (Myriophyllum aquaticum)
  • Fringed water lily (Nymphoides peltata)
  • Water fern (Azolla filiculoides)

Fish:

  • Chub (Leuciscus cephalus)
  • Dace (Leuciscus leuciscus)

Plants:

  • Rhododendron (Rhododendron ponticum)
  • Giant rhubarb (Gunnera tinctoria)

Mammals:

  • Grey squirrel (Sciurus carolinensis)
  • Muntjac deer (Muntiacus sp)


For further information on these and many other problem species, visit the Invasive Species Ireland website - http://www.invasivespeciesireland.com/

 

 
 
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 tel: +353 (046) 9097000, fax: +353 (046) 9097001, email: customerservice@meathcoco.ie
 Council Emergency Telephone Contact Outside Office Hours: 1890 445 335

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 teileafón: +353 (046) 9097000, facs: +353 (046) 9097001, ríomhphost: customerservice@meathcoco.ie
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