As if the water turning red wasn’t scary enough, countless sea creatures then started washing ashore – and all of them were dead.

Certain Florida cities and towns – which at one time had bustled with tourists – have now fallen eerily silent. The locals know why; they’ve gone down to the coast and they’ve seen it firsthand. Their eyes water, and they cough as they look out at the beach, choked up with the scent of dead fish that have washed ashore.

Image: GIANRIGO MARLETTA/AFP/Getty Images

Floridians wouldn’t just find fish on their picturesque beaches, either. Indeed, the entire ecosystem was in danger. Numerous manatees, sea turtles and dolphins had also washed ashore. At some point, a whale shark measuring up at 26 foot in length lost its life, too. And as scientists pored through evidence, they knew exactly what had caused these creatures to die.

The reason could be traced back to the water in which these majestic creatures had once lived. Indeed, the normally deep blue liquid surrounding Florida had slowly changed color to a reddish tint. This occurred because it had become infested with bacteria – and this explained precisely how the animals had died.

As we splash and swim in the oceans, we’re perhaps blissfully unaware of all the living creatures floating near us. Of course, you might envision dolphins jumping out of the surf or fish nibbling at your toes beneath the water. But on an even smaller scale, an unthinkably vast amount of algae float through the ocean.

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In a balanced ecosystem, algae play a pivotal role in keeping things in order. Indeed, they soak up some of the sun’s light energy, ultimately to become a primary food source for extra-small creatures referred to as zooplankton. Perhaps surprisingly, large baleen whales – of which humpbacks are an example – feast on zooplankton.

However, even something as small as algae can become too much of a good thing. Indeed, when they receive too many nutrients, algae begin to multiply at a swift rate. Sometimes, this happens naturally. Say, for instance, a river overflows and dumps soil into the ocean. This would boost algae growth.

Often, though, man stands responsible for an increase in algae production. For instance, washing livestock waste or fertilizer into the water supply can increase its nutrient supply. Or, when we build along the coast, we open these lands up to erosion. Ultimately, the more particles that end up in the ocean, the more likely an algae bloom becomes.

Image: NOAA Great Lakes Environmental Research Laboratory

Regardless of how it happens, algae will react when given too many nutrients upon which they can feast. They multiply at a tremendous rate. So much so, in fact, that they can cause damage to the environment, as well as to human beings. When this happens, scientists refer to the phenomenon as a HAB, or harmful algae blooms.

Different types of bacteria can cause such a bloom. In lakes, for example, a classification of bacteria known as cyanobacteria is typically present. But when water becomes warm and nutrient-rich, these grow out of control. Blooms appear on the surface in a blue-green color that’s often compared to the shade of pea soup.

Sometimes, cyanobacteria spread across the entire surface of a body of water, turning it completely green. In other cases, only small portions of the lake or pond change color. But regardless of their extent, cyanobacteria blooms can also bring with them a smell that’s comparable to that of a swamp.

In oceans, though, algae blooms can cause a sight that’s perhaps even scarier to see than a pea-green lake. Red tides happen as a result of a surge of algae. Because so many algae appear within the water, they change the color of the water from classic blue to a red or brownish shade.

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There’s not a single strain of bacteria responsible for such a transformation. Instead, multiple different types can cause such a creepy display from the ocean’s tides, including Gonyaulax, Dinophysis and Noctiluca. As a more specific example, Alexandrium fundyense causes the surf to go crimson in the Northeastern United States.

A red tide can often spell disaster for the Northeast, where many people depend on the ocean’s waters for their livelihood. You see, when Alexandrium fundyense blooms, it can force fisheries to stop making hauls. After all, they can’t serve algae-affected shellfish to their customers, as such edibles can become toxic.

A related strain of bacteria called Alexandrium monilatum can cause a similar effect in tropical waters, so long as they’re shallow. The Atlantic, the Caribbean, the Pacific and the Gulf of Mexico have all seen red tides caused by this bacteria. Still, in the case of the latter body of water, there’s one strain of bacteria that tends to cause the most problems.

Image: NEON ja — Image: Florida Fish and Wildlife Conservation Commission

When it comes to red tides in the U.S., people most often use the term to describe a bloom of Karenia brevis. You can only see this single-celled being beneath a microscope, but if you’re swimming in the Gulf of Mexico, it’s probably around you somewhere. To that end, K. brevis has appeared along the coasts of both Carolinas, traveling far beyond the confines of the country’s southern Gulf.

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The prime living conditions for K. brevis would have water somewhere between 72° F and 82° F. Typically, the bacteria will strive to stay in the light, and it moves against the direction of gravity. In other words, K. brevis tends to hang out toward the surface of the water.

Surprisingly, scientists have clocked the swimming speed of the microscopic K. brevis. Indeed, they can supposedly cover a whopping three or so feet every hour. And, as it turns out, they’re happy to just float about in the waters of the Gulf of Mexico. The bacteria can be found there throughout the entire year. Typically, there are less than 1,000 K. brevis cells per liter of water.

When K. brevis numbers stay in check, the bacteria can co-exist with the rest of the creatures in the water around it. But once an algae bloom begins, all bets are off. As soon as a red tide rolls in, it serves as a red flag to people not to partake in ocean-centric activities.

People who find themselves on the water or by the shore amid a red tide might experience some bothersome side effects. These might include respiratory pain or irritability to the eyes. The effects will be even worse for those who suffer from asthma or other breathing-related conditions. So these people in particular should stay far from the coast in the case of an algae outbreak.

Indeed, the churning of the tides can crack K. brevis cells, thus releasing dangerous toxins into the air. And the creatures who live underwater in the ocean aren’t immune to the effects of the algae bloom, either. Fish, as well as marine mammals, turtles and birds can all die from exposure to the red tides.

Yet none of this is new information at all. Spanish explorers documented fish die-offs near Tampa as early as the 1500s. And records show that the Gulf of Mexico saw red tides rolling in during the 18th century. On the Florida side of the Gulf, the first time anyone documented a maroon surf happened during the 1840s.

Over time, it seems that red tides have appeared with increased strength and memorability in the seawaters of Florida. For instance, in 2005 a fisherman noticed and reported the start of an algae bloom near the state’s city of St. Petersburg. Quickly, the crimson cloud stretched from there to Naples, then up the coast to Pensacola.

After some ten months of the algae’s presence in Florida’s waters, The New York Times published a piece about its impact. The paper reported that its continued, unmanageable presence had damaged the state’s tourism industry. And to top things off, scientists apparently couldn’t figure out why this iteration of the red wave had hit so strongly.

Locals in the area were reportedly exhibiting the tell-tale signs of suffering from the algae breaking with the waves. They had coughs and teary eyes; they even wore surgical masks to the beach. One affected resident named Juda Bynum assumed that the tide occurred because the planet had a message for humankind. She said, “[Earth is] saying, ‘You’re abusing me bad.’”

Meanwhile, the red tide had wiped out a massive amount of wildlife in its ten-month lifespan. In Pinellas County alone, officials had to orchestrate the removal of more than 950 tons of marine wildlife that had perished in the midst of the red tide. Oyster beds closed down, and fishermen halted business, too.

Allen Walburn – who captained a charter boat for fishing expeditions – complained about the disgusting condition of the water. He also mentioned the fact that his clients couldn’t catch any fish if they wanted to. He described, “[There are] literally no fish. The water just looks putrid. It’s just polluted, stagnant water. It doesn’t even look like water. It looks like chemical waste.”

The same conditions struck again in October 2017 – and with similar staying power as the 17-month red tide that started in 2005. Consequently, University of South Florida College of Marine Science professor Robert Weisberg spoke to the Tampa Bay Times in August 2018. He said, “This is the worst season in the last decade. And I doubt it’s going away anytime soon.”

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This time around, K. brevis appeared in Florida’s waters in stunningly high numbers. As previously mentioned, normal conditions would see about 1,000 cells in every liter of water. But in the fall of 2018, biologist Richard Bartleson told National Geographic that some counts reached as high as 140 million cells within each liter.

Therein lies the problem for much of the wildlife killed off during a red tide. K. brevis creates a toxic by-product known as a brevetoxin. When ingested, it can cause both gastrointestinal and neurological issues so severe that animals die. Its paralyzing effects stop animals from breathing.

Gretchen Lovewell, a program manager for Mote Marine Laboratory’s Stranding Investigations Program, described what it was like to find the animals affected so adversely by the red tide. First of all, she said, those that ingested the brevetoxin appeared “almost comatose” afterward. As she put it, “Their flippers will just be dangling there.”

Image: Rick Loomis/Los Angeles Times via Getty Images

It wasn’t just fish washing ashore with the red tide, either. Within the first eight months of 2018, 80 manatees had died – and scientists suspected their deaths could be traced back to brevetoxin. In the case of the 26-foot-long whale shark that beached, they knew it had died from the red tide. Indeed, its muscles were replete with the toxin.

The Floridian red tide also supposedly wiped out hundreds of turtles, including those from a highly threatened group called Kemp’s Ridley sea turtles. The K. brevis outbreak caused thousands of fish to die, from catfish to pufferfish to trout. Dolphins, crabs and eels have succumbed to the bacteria’s toxic effects, too.

Making matters worse, some of Florida’s freshwater sources dealt with an algae bloom of their own at the same time. In those waters, though, it was the blue-green algae that spread at an electrifying rate. Still, experts believed that both instances were likely caused by a surge of agricultural run-off mixing with warm water.

Indeed, there was evidence that the oceanic red tide had happened at least partly because of such a surge of fertilizer-enriched waters. Prior to 2017’s Hurricane Irma, the U.S. Army Corps of Engineers decided to drain some of Lake Okeechobee’s waters. This was hoped to reduce the chance that it would flood during the storm.

Image: Universal History Archive/Getty Images

Ultimately, it’s difficult to trace an algae bloom back to its initial source. Waters infused with fertilizer could have fed the algae extra nutrients, causing them to grow quickly. But rising temperatures in the Gulf, the amount of salt in the water and light from the sun could have also sparked an outbreak.

Regardless, there’s not much that people can do to stop or, at the very least, weaken a red tide. But some new methods are in testing. One such potential solution uses ozone to kill off K. brevis. Experts also hypothesize that by releasing another type of algae to eat K brevis’s food, they could keep the quantity of the latter in check.

Image: D E N N I S A X E R Photography/Getty Images

Those methods remained in testing during Florida’s 2018 red tide, which meant that the fish-killing conditions had to run their course. By February 2019 scientist Vincent Lovko reported to NPR, “We’ve seen a much reduced number of cell count samples that have elevated K. brevis. That does seem to indicate that the bloom has largely dissipated.”

Even as the red tide disappeared, though, its effects could still be felt in the Florida cities long affected by its presence. Tourists seemed hesitant to return, according to the Visit Sarasota tourism organization’s Erin Duggan. She said, “It’s going to take some time to get visitors to come back. There’s a little bit of a hangover from red tide.”

In the end, NPR reported that hundreds of tons of fish had washed up on the beaches in Manatee, Lee and Sarasota counties. And about 150 dolphins died while swimming through the algae blooms. In the end, hundreds of manatees lost their lives, as did sea turtles who accidentally ingested brevetoxin.

And, for now, all Floridians can do is hunker down and wait for the next red tide that’s likely to hit the Sunshine State. The 2005 bloom lasted longer than the 2018 version, but the state also saw recurrences in 2012, 2013, 2015 and 2016. As Lovko put it, “Generally speaking, we tend to have some level of bloom every year.”