Wales Beaches are Aglow

Natural History
Photo: Shutterstock

Two weeks ago, the dark coast of Wales started lighting up in an ethereal display. Bioluminescence, in the form of swathes of glowing plankton, appeared off the beaches.

Historically known as “the burning of the sea”, it usually occurs in warmer countries like the Maldives and Puerto Rico but can even show up in the Arctic. Bioluminescence in the UK has always been unpredictable but has become more frequent in recent years.

Phytoplankton at Penmon Beach. Photo: Kris Williams

Scientists from local universities suggest that the recent sightings at Caswell Bay, Penmon, and other Welsh beaches owe to particularly stable weather. The alien-like blue glow comes from phytoplankton, whose scientific name is the rather pretty noctiluca scintillans. These photosynthesizing micro-algae bloom exponentially in warm weather and calm seas. High turbidity and low light prevent them from reproducing.

Bioluminescence at Aberavon Beach, Wales. Photo: Emma-Louise Williams/BBC

The blue glow occurs when the water is disturbed and the phytoplankton emits a chemical called luciferin. It is a defense mechanism against predators. It is fairly common in the wake of a ship at night and occasionally even in a small boat’s toilet bowl if it draws its water from the sea.

Near beaches, it tends to occur in sheltered and shallow areas of low turbidity and a greater concentration of nutrients needed for bloom. Despite its beauty, phytoplankton also releases great amounts of ammonia that can threaten surrounding marine life.

Bioluminescence may indicate the sea’s health or lack of it. The phytoplankton thrives in high nitrogen and phosphorous areas. High toxic runoff from pesticides and chemicals from farmlands stimulate the organisms.

Photographers and members of a bioluminescent plankton watching group on Facebook has over 6,000 people. They go out at dusk (where it is most active), and at all hours of the night and early morning to capture the sight on camera.


About the Author

Kristine De Abreu

Kristine De Abreu

Kristine De Abreu is a writer (and occasional photographer) based in sunny Trinidad and Tobago.

Since graduating from the University of Leicester with a BA in English and History, she has pursued a full-time writing career, exploring multiple niches before settling on travel and exploration. While studying for an additional diploma in travel journalism with the British College of Journalism, she began writing for ExWeb.

Currently, she works at a travel magazine in Trinidad as an editorial assistant and is also ExWeb's Weird Wonder Woman, reporting on the world's natural oddities as well as general stories from the world of exploration.

Although she isn't a climber (yet!), she hikes in the bush, has been known to make friends with iguanas and quote the Lord of the Rings trilogy from start to finish.

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