The Saturday of Labor Day weekend in Siesta Key, just off Sarasota on Florida’s Gulf Coast, was a scorcher, with bright blue skies offering the perfect send-off for summer. John Fabian, a charter boat captain, was ready for it, offering two-hour, $400 sightseeing tours of the Intracoastal Waterway, the aquatic freeway that runs parallel to the coast.

Mr. Fabian said he typically brings in $15,000 during Labor Day weekend with his tours, which books up with tourists and snowbirds weeks in advance. But this holiday weekend was different. He’s had no calls, no bookings. This weekend, he had only one client ...

Although no humans have been killed by the tide, local residents have felt its effects: red tide can cause respiratory inflammation and unpleasant itchy or burning skin reactions. A lifeguard at Siesta Key beach said he had used up all of his sick days and vacation days because of bronchitis that he is convinced was caused by the tide.

Read the full article on the effects of the red tide here!