At Lough Neagh in Northern Ireland, sand has been dredged commercially for decades. Large vessels remove sand from the lakebed and transport it to the shore. Because this happens underwater, the scale of the activity is largely invisible. Regulation has focused on where dredging is allowed and how much sand is removed.

Sand is used by the construction industry to make concrete. Demand for sand as a raw material is rising globally. Much of it taken from rivers, coasts and lakes.

But my team’s new research shows that this sand dredging is not just disturbing specific parts of the lakebed. That disruption is much more widespread and may be affecting the entire ecosystem.

Lough Neagh, the largest lake in the UK, supplies drinking water to 41% of the population of Northern Ireland and supports fisheries, wildlife and local livelihoods. Yet it is now at the centre of an environmental crisis. Toxic blue-green algal blooms caused by an overgrowth of the cyanobacteria Microcystis aeruginosa clog up the entire ecosystem.

Lough Neagh has experienced severe blue-green algal blooms each year since 2023, which can damage both environmental and public health. These blooms are mainly driven by nutrient pollution, warming waters and invasive species. Cumulative release of phosphorus and sustained sediment disturbance by dredging probably frees up nutrients in the system that could contribute to thresholds necessary for algal blooms........

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