The return of the blue-green menace that threatens so many

Lough Neagh is the largest freshwater lake in the British Isles and has a surface area of nearly 150 square miles. It provides nearly 40 percent of Northern Ireland’s drinking water and, apart from its importance as a waterbody to a wide range of recreational activities, it also has a significant commercial eel fishery. As someone who lives very close to the eastern shore of the Lough, I consider myself one of the many stakeholders in terms of enjoying the amazing wildlife, breathtaking views and tranquillity that a stroll around the shores of the Lough brings.

But this all changed during Summer 2023. The Lough turned a murky green colour and foul smells filled the air. The cause was a bloom of unprecedented scale and duration of a bacteria known as Microcystis aeruginosa. Such events have happened in other parts of the world, but never before in Lough Neagh. The phenomenon of these massive blooms has been driven by a number of different factors, such as nutrient enrichment caused by agricultural runoff, unchecked sewage and industrial discharges combined with increased surface water temperatures associated with climate change.

When the massive bloom occurred in 2023, there was huge local media attention and blame was attributed to a range of government departments for sitting on their hands for many years without developing any meaningful policies to prevent the event occurring. This was because there was a range of clear warning signs over quite a few years which went largely unheeded. Blame was also directed towards the farming community and local water company for contributing large amounts of the chemical cocktails that the Microcystis bacteria thrives on.

When trying to determine what the risks to human health caused by the bloom were, there again seemed to be a vacuum of data and willingness of government to generate it. This is where one of my colleagues at Queen’s University stepped it. Dr Neil Reid, an environmental biologist, took it upon himself to hire a boat and go out and take a wide range of samples from across the Lough. Myself and other colleagues at the university provided a wide range of testing on these samples and the results were quite devastating. Thirteen potential pathogens that can cause serious human illness – including: E. coli, Salmonella, Enterobacter and Clostridium – were found. Additionally, around a dozen different toxins produced by Microcystis were also found to be present. This work was recently published in a leading scientific journal.

Why this data is so important is that the blue-green menace has returned in Summer 2024, and the authorities can no longer claim that they don’t know what the risks to human health are. An action plan was finally launched recently, and it contains the correct sound bites but many, including myself, wonder if it will be properly resourced to allow delivery of essential changes to how the Lough is managed going forward.

A question posed by many has been in regard to any food safety risks associated with the blooms. The Food Standards Agency (FSA) advised against eating recreationally-caught fish while it carried out tests to determine whether they were safe. The results of the testing (which took many months to organise and finally publish) concluded that there were no food safety risks.

Yet, within the past week, anglers have been told not to eat fish from one of the Lough Neagh rivers. Personally, I wouldn’t entertain consuming anything from the Lough while the bloom is in full tilt.  

The situation is dire, and could be used as a model for how government agencies not taking responsibility for an emerging problem can lead to a crisis. The Irish Times wrote “The lough isn’t just dying, it’s been killed”. I hope it is not as bad as this, but to say it’s in a critical condition is not overplaying the situation.