- Created: 12 November 2012
In October 2009, staff from Inland Fisheries Ireland confirmed the presence Ludwigia grandiflora (Water primrose) in ponds in Sneem, Co. Kerry. It was the first record of this species growing in the wild in Ireland. At the time, this highly invasive species was already causing significant environmental and economic damage in many parts of the world, and was the subject of intensive control measures in Great Britain. The survey of the pond revealed that three other high priority invasive species were also present. These were Myriophyllum aquaticum (Parrot’s feather), Crassula helmsii (New Zealand pigmyweed) and Lagarosiphon major (Curly-leaved waterweed). Although it was deemed prudent to begin an eradication programme as soon as possible, the urgency was somewhat reduced due to the ponds being completely isolated and adjacent from natural freshwaters.
Water primrose is a perennial herb native to South America and some US states. It has deep roots and robust stems that grow horizontally from the edges of the infested water body. The stems can measure up to 5 m in length and can also grow vertically up to approximately 1 m above the water surface. Like many invasive species, this plant is capable of regenerating from small fragments, allowing new infestations to become established easily. Ludwigia grandiflora forms dense, tangled mats in freshwater ecosystems that can result in the depletion of oxygen levels and competition with native species for space and resources.
An initial manual removal operation took place in the ponds revealed that the invasive Ludwigia had survived this removal operation, although only a few specimens remained. This survey, however, also revealed the presence of localised Ludwigia grandiflora stands in neighbouring ponds. An intensive manual removal operation on this occasion, conducted by IFI staff from Swords and the Sneem area, cleared all of the infested ponds of the weed. Dr Joe Caffrey, Senior Research Officer with IFI, stated that he was confident that 99% of the offending invasive plant material had been removed from these sites but that the sites will be closely monitored for any recovery or re-infestation in the coming months and years.
It is worth noting that IFI were originally notified of the presence of this plant as a result of the diligence of a member of the public. The owner of the ponds submitted a specimen to Dr. Matthew Jebb, Director of the National Botanic Gardens, after suspecting that it may be a potentially problematic invasive species. It has now become even easier to report sightings of potentially invasive species since the release of IFI’s new invasive species app. The app allows members of the public to submit sightings, along with a photo, directly to Inland Fisheries. The app is now available from Google Play and the App Store.
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