Increased diversity of Vibrio species in UK waters as temperatures rise

A study led by the University of Exeter assessed the presence of culturable bacterial species in shellfish from multiple sites around England. The findings, published in Water Research, highlight a growing diversity of Vibrio species inhabiting British waters.

Two of the Vibrio species identified - Vibrio rotiferianus and Vibrio jasicida – are not thought to have been recorded in UK waters before. These species can cause disease in shellfish and the increasing range of Vibrio species also raises concerns for human health.

The researchers say the spread of Vibrio species has resulted in a "worldwide surge" of vibriosis in humans and aquatic animals.

"Vibrio species can often be found in UK waters in summer, when temperatures are more favourable for them," said Dr Sariqa Wagley, of the University of Exeter.

"With sea-surface temperatures rising due to climate change, Vibrio activity in the waters is more common, and the diversity of Vibrio species is now increasing."

The study used Met Office data to identify locations where summer sea-surface temperatures were favourable for Vibrio bacteria (based on average number of days per year warmer than 18°C).

Researchers then analysed shellfish samples from four sites used by the shellfish industry – Chichester Harbour, Osea Island, Whitstable Bay and Lyme Bay.

Vibrio parahaemolyticus – the leading cause of seafood-borne gastroenteritis worldwide – was found at one site. Vibrio alginolyticus, which can also cause illness in humans, was identified at three of the sites.

"It is important to note that thorough cooking kills harmful Vibrio bacteria in seafood”, Dr Wagley said.

“However, increasing abundance and diversity of Vibrio bacteria creates health risks not only for people eating seafood, but for those using the sea for recreation purposes – either due to swallowing infected seawater or from the bacteria entering exposed wounds or cuts.

"Vibrio bacteria are also a threat to a variety of marine species including shellfish themselves. Disease costs the global aquaculture industry £6 billion a year, and this burden of disease can be devastating.

Dr Wagley added: "Our findings support the hypothesis that Vibrio-associated diseases are increasing and are influenced by the rise in sea-surface temperature.

"We need to monitor this situation closely, to protect human health, marine biodiversity and the seafood industry."

Article: Harrison, J., Nelson, K., Morcrette, H., Morcrette, C., Preston, J., Helmer, L., Titball, R. W., Butler, C. S., Wagley, S. (2022). The increased prevalence of Vibrio species and the first reporting of Vibrio jasicida and Vibrio rotiferianus at UK shellfish sites. Water Research, 211, 117942, doi: 10.1016/j.watres.2021.117942