HUTCHINSON ISLAND — Low levels of red tide have been found at Bathtub Beach, one of the most popular beaches in Martin County.

Staffers at Harbor Branch Oceanographic Institute at Fort Pierce sampled water Monday at the beach on the southern end of Hutchinson Island, said Martin County spokeswoman Martha Ann Kneiss.

Harbor Branch, a division of Florida Atlantic University, also found moderate levels of red tide at the Jupiter Inlet, just south of Martin County, Kneiss said.

The Bathtub Beach sample contained 40,000 red tide cells per liter of water, Kneiss said. Between 10,000 and 100,000 cells per liter is considered low, but enough to cause respiratory irritation and possible fish kills, according to the Florida Fish and Wildlife Conservation Commission.

Previously: Red tide confirmed in Palm Beach County, suspected in Martin

The Jupiter Inlet sample contained 200,000 red tide cells per liter, Kneiss reported, That's enough to cause "respiratory irritation and probable fish kills," according to the FWC.

The state agency declined to report when and where it will be sampling for red tide on the Treasure Coast. Spokeswoman Susan Neel said FWC will provide an "update online Wednesday and again Friday."

Martin County plans to do its own testing at Bathtub Beach, Hobe Sound Beach and Jensen Beach, Kneiss said.

St. Lucie County's Environmental Resources staff collected seven samples Monday, county spokesman Erick Gill said Tuesday evening.

"FWC confirmed receipt this morning," Gill said, and results should be sent back to the county by Wednesday.

Beach visit cut short

When Valerie Everhart found out about the risk of red tide Tuesday afternoon at Bathtub Beach, she decided to cut her visit short.

Not just out of concern for her own health, but for her daughter, Myra, who turned 1 last week.

Everhart had heard about red tide concerns over the past weekend.

"I thought that had cleared up," the Jensen Beach resident said, because lifeguards, who had left Martin County beaches Sunday after irritants in the air made them cough, returned to work Tuesday.

"Yeah, I'm concerned," Everhart said. "But I thought it wasn't that big an issue anymore."

Actually, it's not known how big an issue red tide is along the Treasure Coast. Although low to medium levels of the often-toxic algae have been confirmed off Palm Beach County beaches, the FWC has yet to say whether it has sampled or tested water in Martin, St. Lucie and Indian River counties.

Bathtub Beach had only a handful of visitors — most of them out-of-town tourists — Tuesday afternoon. Perhaps that was as much because of high surf and strong easterly winds as the possibility of red tide.

More:St. Lucie County beaches to be tested this week for algae bloom from Fort Myers

Tim and Luanne Sjostrom, of St. Charles, Illinois, thought red tide was a problem only on Florida's Gulf Coast.

"We were going to come to the beach anyway," Luanne Sjostrom said. "But we haven't gotten in the water except to get our feet wet."

Luanne Sjostrom said she had a sore throat, "but I've had one since last week after I got a flu shot."

"I haven't felt anything," Tim Sjostrom said.

More: What is red tide? Here's what you need to know

Dangers of red tide

Red tide currently is causing serious environmental damage — killing fish, sea turtles, manatees and even a massive whale shark — and making people sick on Florida's southwest coast.

Some of the algae, which is common in the Gulf of Mexico, may have gotten caught up in currents and come to the state's Atlantic Coast, where it's extremely rare.

Because the bloom is not as intense on the East Coast, effects of red tide aren't expected to be as serious.

Although the FWC says most people can swim in red tide, it can cause skin irritation and burning eyes. (If that happens to you, get out of the water and wash thoroughly with freshwater.)

The Florida Department of Health advises people with severe or chronic respiratory conditions to avoid red tide areas.

Some people may experience eye, nose and throat irritation, as well as coughing, wheezing and shortness of breath, when on the beach or in an area near a red tide bloom, particularly when winds are blowing onshore.

Like they have been since the weekend.

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Two TCPalm staffers who talked to beachgoers Tuesday at Bathtub reported scratchy throats and a not-quite-dizzy feeling after about 30 minutes on the beach.

Jensen Beach-based Ecological Associates, which monitors sea turtles nests on beaches every day throughout the Treasure Coast, haven't reported any adverse effects from possible red tide, either to staffers or turtles.

"We haven't felt anything or seen anything, no dead fish or any other sea life," said Senior Scientist Niki Desjardin. But beach patrolers have been issued face masks "just in case."

More: 2018 turtle nesting season unpredictable, expert says

The sea turtle nesting season runs from early March to mid-November, and most of this year's turtle nests have been laid, Desjardin said, but there are still hatchlings emerging, apparently with no adverse effects from red tide.

Hundreds of dead sea turtles have washed ashore on Florida's west coast.

Concerned about red tide?