An invasive species of mussel has been discovered in the two great lakes on the Shannon, Lough Ree and Lough Derg.
The discovery of the Quagga mussel earlier this summer has led to concerns regarding the impact it could now have on the ecology and nutrient dynamics of Ireland's longest river.
The Quagga mussel is native to the Dneiper river drainage of Ukraine and the Caspian sea.
It is unknown how they were introduced into Ireland but it is thought the most likely source was as a contaminant /hitchhiker on boats or equipment brought from infested areas into Irish waters.
The Quagga mussel was detected during a survey of Lough Ree by a team of researchers from UCD.
They have described the presence of the Quagga mussel in Lough Ree as "abundant over a wide range of depths, and are also present in the Shannon between Lough Ree and Lough Derg".
Dr Dan Minchin of the Lough Derg science group said that Quagga mussel is a filter feeder which is likely to result in further changes to water quality and nutrient dynamics in the Shannon.
He warned the mussel will compete with native mussels and could have an impact on water quality and the ecological status of the Irish aquatic ecosystems.
It can also lead to blocking and fouling of man-made structures and of boat propulsion and water cooling systems.
"I think it is almost certain it's going to spread and it is almost certain we're going to have problems as a result of this mussel having arrived here," Dr Minchin added.
Members of the public are being asked to report any sightings of the Quagga mussel species to the National Biodiversity Data Centre.
Boat and watercraft users are being asked to clean all equipment and vessels before moving between waterways, in an effort to help prevent the spread of the species.
The Quagga is under a rapid assessment field study managed by the Invasive Ecology (InEco) laboratory, School of Biology and Environmental Science, UCD.