Marea roja
A massive bloom of microalgae that stains the water red or brown and can affect fish and swimmers. In Puerto Rico it is not a routine event, and what does arrive every year is sargassum, which is a different thing. When something like it happens, local agencies close specific beaches and announce it.
Example
When a beach is closed for water quality, the reason is usually bacterial after heavy rain rather than a red tide.
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Related terms
Coast and sea
Sargazo
A brown seaweed that arrives in floating mats from the Atlantic and piles up on the shore, mostly between spring and...
Coast and sea
Dinoflagelado
A single celled marine microorganism that fires a flash of light when the water is stirred. It is what makes the...
Coast and sea
Balneario (playa pública)
A government run public beach with restrooms, showers, parking and lifeguards during set hours. There is usually a...
Coast and sea
Bahía bioluminiscente
An enclosed bay where the water lights up blue green when disturbed, thanks to a dense population of light emitting...
Frequently asked questions
Is it the same as sargassum?
No. Sargassum is a large floating seaweed that piles up on shore. Red tide is a microscopic bloom that colors the water.
How do I know a beach is safe?
Island environmental agencies publish advisories and closures by beach. A sign at the public beach entrance is the most direct signal.
