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The Harmful Algal Blooms in Florida

Our team breaks down what is going on with the Florida red tide events and harmful algae blooms.

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© Jeff Watters

The news and photos of the massive red tide this month in southwest Florida are absolutely heartbreaking. As a seasoned conservation biologist (Baldera) and a native Floridian (Brooker), we have never seen a red tide event as severe as this with such far-reaching and appalling fish kills. We have received reports of massive, 200-pound (and larger) goliath groupers washing up on beaches in Longboat Key and in Sanibel. Over 300 sea turtles, 100 manatees and a dozen dolphins have also been killed, as well as a young whale shark. We have seen firsthand hundreds of inshore and offshore fish of varying species floating at the mouth of Tampa Bay and piled up on beaches as far south as Naples.

The algal bloom keeps spreading further and further

Dead fish are washing up regularly now even as far north as Pinellas County, and scientists are detecting elevated concentrations of the red tide-causing microorganism up to Madeira Beach, meaning that this red tide event is spanning six Florida counties and covering over 100 miles of shoreline, with a reach offshore to at least 40 miles. That’s an area approximately as large as the entire state of Connecticut that is teeming with harmful red tide, killing marine creatures and spoiling the coast.

Send us your Florida red tide photos

We want to see firsthand what you are seeing in Florida. Send us your photos and we’ll print them off and deliver them to the Florida State legislature. Let’s make an impact they can’t ignore!

 What is red tide?

Throughout the summer, the normally blue waters off the coast of Florida have been turning brown, red and green, killing wildlife and making people sick. The reason for the declining water quality is grouped under the phrase “harmful algae.” The problem is complicated. First, there is a naturally occurring event called the red tide. In Florida, red tide is caused by a dinoflagellate, or marine microorganism called Karenia brevis. About once a year, when conditions are right, K. brevis “blooms” along Florida’s coast. The Florida red tide can be found in bays and estuaries but not in freshwater systems such as lakes and rivers. Because K. brevis cannot tolerate low-salinity waters for very long, blooms usually remain in salty coastal waters.

Second—adding to the harmful algal blooms along Florida’s coast—are the human-made algae blooms caused by polluted outflows that start inland and carry the problems of pollution and harmful algae to the coast. Pollution, such as fertilizer, from inland sources is either washed or diverted into the ocean where it fuels algal blooms. These algae cause a green sludge-like bloom along the coast and also are naturally occurring. But in this case, our inland decisions have disrupted the natural processes that keep the algae at normal, safe levels.

Combine the naturally occurring red tide event with the ever-increasing problem of human-made algae blooms caused by pollution, and you have the catastrophic events that have been harming wildlife and coastal communities in Florida all summer.

How does this affect humans and wildlife?

Red tides are hard to ignore because the microorganisms emit brevetoxins, which, as they are transferred through the food web, can paralyze fish gills and cause animals like manatees and sea turtles to become sick or die. Humans also suffer when the toxins get blown into the air, constricting the lungs’ bronchioles and sending people with asthma and other health issues to emergency rooms with coughs and shortness of breath. Even algal blooms that don’t release toxins can harm wildlife by depleting oxygen from coastal waters, causing massive fish kills in numbers too vast to count.

Coastal communities are being harmed

This summer, the severity of the red tide and the impacts on fish and wildlife are also affecting our economy in Florida. Hotels and restaurants depend on clean air and water to bring visitors to their businesses, and right now the health concerns created by harmful algal blooms are keeping people away.

As people who love the ocean and the beach, as well as members of an organization that works for ocean solutions, we cannot ignore this. Florida residents are raising concerns all around the state, asking for action from the state government and our elected officials. Although this year’s blooms are especially bad, harmful algal blooms are a regular occurrence in Florida. Places like the Indian River Lagoon, Fort Myers and Florida’s Treasure Coast—to name a few—have frequent harmful algal blooms. What causes the blooms depends on that specific area, but overall we know that the combined pollution from septic tanks, fertilizer runoff (from lawns and agriculture) and increased development put pressure on Florida’s ecosystem. Floridians want change and a commitment from the state that clean water is a priority.

We don’t have all the answers yet, but we know we have to act. We know that we have to come up with new solutions to fix this reoccurring problem. As we continue to track and understand the red tide and other harmful algal blooms in Florida, we will look for ways we can help.

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