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Harmful algal blooms (red tide)

Red tide and other blooms: official samples (Florida FWC) and possible blooms from satellite.

Why it is a problem

Some algae make toxins that kill fish, sea turtles, birds and marine mammals (NOAA). [source]
Red tide (Karenia brevis) toxins in sea spray can irritate eyes, nose and throat and worsen asthma; eating contaminated shellfish can cause neurotoxic shellfish poisoning (CDC). [source]
Blooms close shellfish harvesting, cause fish kills on beaches, and hurt tourism and local businesses (EPA). [source]

How they form: algae multiply when light, temperature, salinity and nutrients suit them; nutrient pollution can feed and prolong some blooms (EPA). [source]
How they spread: currents and wind move blooms along the coast and onshore; red tide can last weeks to months.
What we show: Confirmed (FWC) = Florida water samples with Karenia brevis above 1,000 cells per litre. Possible bloom (satellite, unverified) = chlorophyll anomaly from Sentinel-3 OLCI, the method used for NOAA's Gulf of Mexico HAB bulletins (Stumpf et al. 2003). [source] [source] [source]
Other methods: Red Band Difference / fluorescence (Hu et al. 2005) and OLCI MCI (Gower et al. 2005) are established, but need data we do not process yet. [source] [source]
Limits: clouds hide blooms; muddy or shallow coastal water and river plumes look like blooms; no satellite can tell whether a bloom is toxic, only water samples can. Satellite flags are run for the Gulf of Mexico only.

Everyone: Use less fertilizer, pick up pet waste, keep septic systems working (EPA). [source]
Beach-goers: Check FWC / local health advisories; avoid swimming near dead fish or discoloured water; people with asthma should avoid red tide beaches.
Policy: Reduce nutrient runoff from farms, cities and wastewater; fund monitoring and forecasting.

Do not touch oil, tar balls, dead animals or unknown containers; keep children and pets away; never board a derelict vessel.

Anywhere at sea: Call the local coast guard on VHF channel 16 or your country's emergency number. Give position, time, what you see, and photos if safe.
United States (incl. Puerto Rico, USVI, Gulf coast): Oil or chemical spills: US Coast Guard National Response Center, 1-800-424-8802 (24 h), nrc.uscg.mil. Derelict vessels: state contacts in NOAA's ADV InfoHub.
Florida red tide / fish kills: FWC fish kill hotline 1-800-636-0511, or report online at myfwc.com. Health questions: Florida Poison Information Center 1-800-222-1222.
Mexico: Emergencies 911. Navy (SEMAR) for pollution at sea; environmental complaints to PROFEPA.
Brazil: Maritime emergencies 185 (Marinha do Brasil). Environmental reports: IBAMA (Linha Verde).
Chile: Maritime emergencies 137 (DIRECTEMAR, free, nationwide).
Argentina: Nautical emergencies 106 (Prefectura Naval Argentina).
Colombia, Peru, Central America and others: Contact the national maritime authority / coast guard (e.g. DIMAR in Colombia, DICAPI in Peru) or the local port captain.
Also on this site: Use Report an incident on the map. Reports appear marked unverified. This site does not alert authorities for you.