Signs of red tide creep up to Melbourne Beach, Indialantic

INDIALANTIC, Fla. – While test results to prove red tide are pending, the itchy throats and rancid fish carcasses on the beach this week have some already convinced, and fearing a repeat of the toxic tides that thoroughly flogged the Space Coast 16 years ago.

For tourists, another red tide now would be lousy timing. For fish, too.

"Right now we've got a big mullet run on the beach, so there are a lot of migratory fish following the mullet runs," said Jon Shenker, associate professor of marine biology at the Florida Institute of Technology told News 6 partner Florida Today. "I have no idea how bad this is."

Beachgoers and beachside residents have complained in recent days of coughing and irritated throats after being by the ocean. Dead fish reported in Indialantic and Melbourne Beach on Tuesday included bluefish, Spanish mackerel, mullet and other fish. A dead fish dotted the shoreline every 10 feet or so at Paradise Beach Park.

[READ: Scientists search for 'smoking gun' in Florida's red tide]

Brevard County is helping Florida Fish and Wildlife Conservation Commission gather water samples to test for the red tide organism, Karenia brevis. The algae releases a neurotoxin that can cause asthma-like symptoms. If ingested, it can cause digestive problems. Brevard County Natural Resources has coordinated with FWC for sampling beginning Tuesday and hopes to know the results on Wednesday.

"In the meantime, we have been monitoring conditions and have reached out to various agencies, such as Keep Brevard Beautiful, Tourism and Development, the city of Cocoa Beach, to plan for a coordinated response if and when we have reported fish kills," Brevard County spokesman Don Walker said via email.

Red tide has killed fish for months on Florida's Gulf Coast. Some biologists thought Hurricane Michael might help to break up that algae bloom. But it's also possible that the organism responsible for the outbreak could be recharged by the nutrients washing back into the Gulf, spreading its deadly impact over an even wider area.

[RELATED: Florida governor declares emergency over red tide for 7 counties]

For those wanting to track the algae bloom's migration, FWC created a new red tide daily status map. 

Respiratory irritation usually occurs at red tide levels of 1,000 cells per liter or greater. 

A federal study released in 2007 linked red tide to excess nutrients from farms and development along the Mississippi River that can trigger the blooms along the continental shelf in the Gulf of Mexico. Currents loop the toxic algae around Florida toward Brevard,  which happened in November 2002, when a red tide lasted through the New Year. Tourism and coastal residents suffered.

Red tide's toxin can cause shellfish poisoning and is a threat to fish, dolphin and manatees. The state typically closes shellfish areas when levels reach 5,000 cells per liter. More than  1 million cells per liter causes fish kills and the water sometimes to turn dark red, green or brown.

[READ: Here's how you can help improve the condition of Florida's waters]

Brevard also had a brush with red tide in November 2007, when low levels of the algae turned up in samples gathered from Cocoa Beach, the Mosquito Lagoon, to St. Johns County.

If this week's samples prove red tide is here, then multiple environmental factors will determine whether it lasts as long as what Brevard saw in 2002, biologists say.

"It would depend on the nutrient supply," Shenker said. "Depends a lot on the stability of the local ocean."