Don’t Panic! The Slimy, Smelly Stuff on Beaches Is Just Algal Bloom
Spotting sludgy goo with a nasty whiff on the beach? Relax, it’s just a natural algal bloom. When sea temperatures rise, tiny algae multiply fast, creating these slimy patches. Although they look and smell awful, they’re harmless.
What Is Algal Bloom? Spotting It on Beaches
- Lasts about four weeks before fading away.
- Often mistaken for sewage due to the smell.
- Covered in foam on water or shore—this is algae breaking down.
- Forms colonies that look like frog spawn or oil drops in early summer.
British waters see blooms of Phaeocystis during summer—non-toxic algae thriving on sunshine and warmth. When they die down, they give off a rotten egg or veg-like smell and create creamy-brown foam. Near cliffs or headlands, wave action can gather this foam into thin lines or thick blankets on shores.
Meet the ‘Sea Sparkle’: The Glow of Noctiluca
Another algae you might see is Noctiluca, known for causing “red tide” by colouring water red, orange, or brown. It creates scum and glows in the dark—earning the nickname sea sparkle thanks to its bioluminescence.
Safe to Swim? The World Health Organization Weighs In
“Risks to humans from contact, swallowing, or breathing in these marine algae are low,” says the World Health Organization.
So while the sight and stink of algal blooms might put you off your beach day, they’re no threat to your health. Just enjoy the sea!
