What you need to know about red tide

Q. What happened?

On Saturday, multiple people on north county beaches complained of respiratory, skin and eye irritations, prompting a health advisory and the closure of beaches from the Martin County line to Lantana. The Karenia brevis algae, which causes red tide, is present in Palm Beach County’s coastal waters, according to preliminary results Monday from the Florida Fish and Wildlife Conservation Commission.

Q. What do the tests show?

The water samples do not show how high of a concentration is present, but more information is expected in coming days.

Q. What is red tide?

Red tide is a bloom of the Karenia brevis algae that is naturally occurring in the Gulf of Mexico. The algae is rare on the East Coast because it prefers the calmer, more stratified water of the Gulf. This summer, one of the worst red tides on record was recorded with massive fish kills and dead manatees, dolphins and turtles. The toxin affects the nervous system of marine life, causing paralysis in some cases.

Q. Will we see the same kind of fish kills?

Red tide is typically not as intense on the East Coast as it is on the West Coast because Atlantic waters are more active, which helps mix the water so it’s less stratified and has higher salinity throughout the water column. Red tide prefers salty water, but not as salty as fullstrength sea water.

Q. Has coastal pollution caused the Florida red tide?

Harmful algae blooms thrive in nutrient-heavy environments. Hurricane Irma and heavy spring rainfall caused runoff heavy in nutrients to flood into Lake Okeechobee and the southwest watersheds that feed into the Gulf of Mexico.

Q. What does red tide smell like?

Red tide doesn’t have a scent. It releases a toxin as a defense mechanism, that when released into the air can cause coughing, runny noses and wheezing.

Q. Are red tide health impacts permanent?

For most people, symptoms are temporary. People with chronic respiratory problems like asthma and COPD should avoid red tide areas.

Q. How could it have reached the East Coast?

It’s unusual for the East Coast to get a red tide bloom. This year, it’s possible the red tide got caught in the loop current that flows through the Florida Straits and into the Gulf Stream. With strong easterly winds last weekend, the red tide may have been blown closer to the beach. Waves help to make the toxin into an aerosol.

Q. How long will red tide last?

Red tide can last for a few weeks to longer than a year. The current red tide bloom on the West Coast began in October 2017. It peaked with the massive fish kills during the summer when onshore winds blew it toward the coast.

Q. What’s the difference between red tide and blue-green algae?

Red tide lives in saltwater, while blue-green algae, which is actually a cyanobacteria, lives in freshwater. Lake Okeechobee and the northern estuaries have been plagued by a blue-green algae bloom all summer. Both red tide and blue-green algae thrive in high-nutrient environments, but more study is needed to determine how or whether the two interact.

Q. Are red tides red?

A high concentration of the Karenia brevis bloom can turn water brown.