Marine Heatwaves Could Affect Water Quality and Public Health, Experts Warn

Scientists are warning that increasingly frequent marine heatwaves around the UK could have implications for water quality, marine ecosystems and public health as sea temperatures continue to rise.

According to the Met Office, UK waters have already reached temperatures typically seen in August, with some coastal areas experiencing exceptionally warm conditions. Experts say these marine heatwaves are expected to become more common as the climate continues to warm.

Researchers warn that warmer seawater can create conditions that increase the likelihood of harmful algal blooms and the growth of certain bacteria. This may reduce water quality and increase the risk of illness for people using coastal waters, while also affecting marine habitats and the aquaculture industry, including shellfish farming.

Scientists have also highlighted the potential impact on marine wildlife. Rising sea temperatures can alter the distribution of fish and other marine species, place stress on cold-water ecosystems and increase the risk of fish mortality during prolonged periods of unusually warm water.

Experts say warmer seas may also have wider environmental consequences by damaging habitats such as seagrass meadows and kelp forests, which play an important role in supporting biodiversity and helping to store carbon.

While the risks to human health remain relatively low for most people, experts advise following local public health guidance if warnings are issued about water quality or harmful algal blooms before swimming or taking part in water-based activities. Monitoring coastal water quality and marine conditions remains an important part of protecting both public health and the wider environment.

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