Red tide appears at low levels in Indian River lagoon, worrying manatees

BREVARD COUNTY, Florida. – Following the worst year on record for manatee deaths, Florida wildlife officials last week uncovered another potential killer of the endangered species in the Indian River lagoon – red tide.

While currently only at background levels, the presence of toxic algae in Florida’s most important sea cow habitat portends a tough summer for the endangered species, reports Florida Today, partner of News 6.

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The closed and almost stagnant nature of the 156-mile-long lagoon – which has few inlets to let ocean water wash away algae – increases the risk to manatees and other marine life, if the tide red was reaching flowering levels this summer.

If the algae thickens to high enough concentrations to emit lethal levels of toxins, it could be fatal for manatees when they come to the surface of the water to breathe, inhaling the poisons.

It can also sicken or, at very extreme levels, kill bottlenose dolphins. A red tide in southwest Florida killed at least 174 bottlenose dolphins there in 2018, according to the National Oceanic and Atmospheric Administration.

It could also claim the lives of countless fish and other marine life, and cause respiratory and neurological symptoms in humans, when toxins aerosolize in sea spray.

On Wednesday, June 15, the red tidal algae, called Karenia breviswas observed at background levels in a sample taken from the Indian River Lagoon at the NASA Causeway, according to data from the Florida Fish and Wildlife Conservation Commission released Friday evening

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FWC tests showed no red tide off Brevard beaches.

FWC also found background and very low levels off Collier County in southwest Florida over the past week.

“Background” means the level was less than 1000 cells per litre, which should not cause adverse effects. But when levels exceed 1,000 cells per litre, people may experience respiratory irritation and shellfish harvesting may shut down.

When levels reach more than 100,000 cells per liter, a concentration considered “medium”, the fish will die and the satellites will pick up the increase in chlorophyll on the surface of the water. At over a million cells, considered “high”, the water turns red and the death toll worsens.

The advent of red tide in the Indian River lagoon follows last year’s record 1,101 manatee deaths in Florida.

Until June 10 this year, 588 manatees have died, compared to 799 until June 10 last year and a five-year average of 419 for this period. FWC suspects that most of the manatee deaths last year were due to starvation. This year, 330 manatees died in Brevard, or 56% of the total.

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The death rate in 2021 prompted the state agency IThis winter, we embarked on a first-ever pilot program to feed manatees lettuce in the wild – from the Florida Power & Light Co. power plant in Port St. John.

In October 2018, red tide reached “high” levels in Brevard, Indian River and St. Lucia counties, according to FWC sampling, triggering fish kills on the beach. The toxic algae caused the carcasses of mullet, mackerel, menhaden and ladybugs to wash up on the shore.

There have been no reports of fish kills believed to be linked to the red tide in the past week.

The next situation report will be published on Friday, June 24.

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