Water pollution helps invaders - Let’s eradicate pondweed

THE impact of invasive species of plants that grow on land such as rhododendron or Japanese knotweed is obvious and can be startling. 

Rampant rhododendrons, despite decades of effort to eradicate them, are changing the very character of Killarney National Park. Japanese knotweed damages buildings, hard surfaces and underground services in its relentless quest for light. Its eradication is very challenging too.

However, invasive species of plants that we cannot immediately see are also changing the Irish environment in profound ways. Various pondweeds grow quickly underwater and can have a devastating impact on native plants, fish and life-sustaining oxygen levels in waters where it becomes well established. Eradicating these weeds is very difficult — as Inland Fisheries Ireland have discovered. It can propagate from even the smallest fragment of a plant and some measures taken to eradicate it have, unfortunately and unintentionally, helped its spread.

New research shows that polluted water is especially susceptible to supporting an invasion of pondweed. In an unfortunate double whammy, a strong correlation between nutrient or phosphate overload and the occurrence of aquatic plant species has been established. In a country that has yet to take its environmental obligations seriously, it may be difficult to eradicate these plants but, like our failure to curb greenhouse gas emissions, that would be a mistake and a pity.