Lough Neagh, the largest freshwater lake in the UK and Ireland, is the heart of a vast interconnected aquatic ecosystem, from its surrounding catchment area to the rivers which flow into it and flow out to the north coast.
In recent years, that heart has been under increasing pressure and, in 2023, an unprecedented blue-green algal bloom appeared, causing immense public interest and which was visible from space.
In this video, we meet David Jewson, a former researcher on the lough for over 30 years at the Ulster University.
David and local people around the shores have witnessed a decline in the number of swarms of Lough Neagh Fly which would have been incredibly dense previously. They remember how the swarms looked like ‘smoke’.
Lough Neagh Fly include several species of non-biting Chironomid midges.
The female midges fly up to a mile off-shore to lay their eggs on rafts on the surface, which then hatch and the larvae sink to the bottom, where they would normally be feeding on algal cells sedimented out of the water.
They have a four stage life cycle, taking over a year.
David believes that the swarms have declined due to the arrival of an invasive species, the zebra mussel, whose population has been increasing for the past 20 to 25 years.
The key factor is the competition for food but the zebra mussel has an advantage because it’s a filter feeder, filtering non-toxic algae out of the water before it can reach the bottom where the midge larvae would have fed on it.
It’s an important interaction and change in the food web.
The good news is that AFBI and Queen’s University Belfast are working together to look into the interaction between the fly and the zebra mussel.
The views and opinions on the subject of this video are that of the contributor.
