Residents and visitors in North Wales have recently noticed unusual discolouration of the sea, sparking concerns about potential pollution. The water turned a striking orange near Anglesey and a murky brown shade in Gwynedd, prompting investigations by local authorities.
Orange Water at Anglesey
A concerned citizen reported the orange water between Llanddona and Red Wharf Bay, fearing a pollution incident. Penmon Coastguards investigated from multiple vantage points and confirmed the cause was a bioluminescent algae bloom. This natural phenomenon appears orange or brown in daylight but produces a brilliant neon-blue glow at night when agitated.
Bioluminescence is created by tiny plankton as a defence mechanism to startle predators in the dark. While unpredictable, these displays are becoming more frequent on UK beaches due to warming climates.
Brown Water at Gwynedd
Separately, Natural Resources Wales (NRW) investigated reports of the sea turning murky brown at Porthdinllaen beach in Gwynedd. Locals feared a sewage leak over a holiday weekend. NRW confirmed no sewage leak occurred; the discolouration was due to a non-toxic algae called Phaeocystis. This common bloom-forming algae is triggered by sunlight and warmer temperatures, creating a brown, frothy scum that is entirely safe.
Conclusion
Both incidents are natural events, not pollution. Anyone with concerns about future pollution can report them to NRW via their online form or 24/7 hotline.
