Deep Dive: Florida’s Red Tide

We were on the hard in Ft. Myers for over a week (Oct. 14 to Oct. 23rd –read about our haul out here), and when we arrived we were admittedly distracted by our haul out and getting settled in our on-land accommodations, with so much stuff we lugged there for our many projects to work on during the week. However, as the week wore on and as we were spending lots of time outside walking to and from the boat yard, to the store, and strolling on the beach, we began to develop a bit of a cough when we spent an extended time outside. Then it wasn’t long before a walk on the beach was accompanied by an indescribable odor, and lots and lots of dead fish washed up on shore. Suddenly our throat tickle and cough after walking outside made sense. We knew this area (Lee County, southwest Florida) had an extreme occurrence of red tide last year in 2018, but apparently our time in Fort Myers coincided with an unfortunate resurgence of red tide in this part of Florida. 

Taken after strong storm winds (Nestor) blew inland some algae and seaweed with a noxious odor - littered in the debris on shore are loads of dead fish
The start of a new season of red tide blooms along Florida's southwest coast. Gulls picking through the seaweed for scraps

Harmful algae blooms (“HABs”), like red tide, develop in waters when certain kinds of toxic or nuisance algae that exist in an area year round but at low concentrations meet certain conditions (temperature, nutrient levels, wind and light) that lead to rapid growth and formation of large patches or blooms in the water. Harmful algae blooms have developed in numerous coastal and lake regions in the US (nearly if not all coastal states – and even in Australia) from Green Bay, Wisconsin to Lake Pontchartrain, Louisiana to Albemarle Sound, NC, and including areas in southwest Florida. Three species of dinoflagellates and one diatom species are to blame for the creation of red tides that occur in the U.S., and each functions differently in the face of particular conditions that transform its normal low levels in lakes, rivers, estuaries and oceans into toxic blooms. Red tide blooms typically start offshore (10-40 miles) and are carried inshore by winds and current. Nutrients in the water, nitrogen and phosphorus in particular, from sources that vary among the surrounding (typically from agricultural runoff and fertilized lawns) environment feed the growth of red tide once the bloom moves inshore, causing an expansion of the bloom and perhaps longer lifespan in the area, from days, to weeks or even months. Parts of Florida also suffer from marine and estuarine species of blue-green algae (more accurately referred to as “cyanobacteria”), such as Trichodesmium (of which blooms in the Gulf of Mexico have been found to be fueled annually by dust from the Sahara Desert interestingly enough), which consume nitrogen from the atmosphere and at death actually provide nutrients needed for Florida’s red tide organism to flourish.

Florida’s “red tide” organism is one of the most well-known and harmful of the more than 50 HAB species in the Gulf of Mexico, caused by a particular dinoflagellate, Karenia brevis, an algae variety found in the Gulf of Mexico that emits powerful neurotoxins (“brevetoxins”) that endanger human health and wildlife. These brevetoxins affect marine animals from fish, invertebrates, sea turtles, birds (commonly affected species include double-crested cormorants, lesser scaup, and brown pelicans) and marine mammals (dolphins and manatees that consume contaminated prey). While major fish kills have been observed in association with red tide events since the mid 1800’s, it was not for another century, in 1946, until the organism responsible for the kills, K. brevis, was identified. And sadly, despite historical occurrences, the red tides in Florida have become more frequent, long-lasting and expansive.  

But one of hundreds of dead fish washed ashore in Fort Myers during our week there. The birds were eating the dead fish, which were rotting in sea grasses and reddish foam that had washed ashore.

The throat tickle, persistent cough and noxious stench we experienced is consistent with exposure to the toxins emitted from red tide which can be suspended in the air near the beach and cause respiratory illness in humans. Likewise, the multitude of dead fish littering the beach is an unfortunate indication of an area suffering from red tide as this algae bloom will cause the water to become discolored and widespread fish, turtle, bird and other marine animal deaths. Moreover, people who consume shellfish contaminated with K. brevis brevetoxins can suffer Neurotoxic Shellfish Poisoning. It is no surprise then that these blooms have a significant impact on Florida’s economy – with coastal communities losing millions of dollars as perished marine life litters beaches, tourists suffer eye and respiratory irritation and fishers lose income due to closure of shellfish beds in infected areas.

The longest red tide bloom on record since the Florida Fish and Wildlife Conservation Commission began to collect data in 1953 lasted for 30 months, between the years of 1994-1997. In the past twenty years, the Gulf of Mexico has experienced unprecedented red tide events in terms of severity of impact — to fish, marine mammals, sea turtles, residents and coastal economy — and in terms of reach, contributing a 2000 square mile dead zone in the Gulf. So while this is not a new phenomenon, and occurs almost every year in the Gulf, its intensity and lifespan appears to be growing.

Studies suggest that human intervention and pollution exacerbates a red tide event. Inland waters laced with high levels of fertilizer nutrients (phosphorus and nitrogen) as a result of runoff from agricultural fields have been flagged as a likely source of pollution contributing to the growth of red tide. However, uncertainty looms, most likely because while the state of Florida has contributed resources and research to track red tides as they occur, there has been little done to actually address contributory causes or pollution that drives them. The state had pulled back water quality monitoring and agency oversight intended to investigate and protect from unsustainable pollutants in the state’s waters that drain to the coast. This disparity between the political forces making regulatory and policy calls for Florida and the academic and professional researchers seeking information to assist in the prediction and reduction of red tide bloom conditions is a relationship not limited to this state, but indicative of a greater disparity amongst state and federal level decision makers and the needs of on-the-ground advocates seeking answers. Refusal to assess, investigate, monitor and address the causes of an event that harms human health, economies and the environment will never lead to sustainable, long-term resolutions.

Florida’s disruption of natural flow and filtration of waters through the Everglades by redirecting flows, and excess nutrient pollution, combined with the major influx of upstream agricultural runoff and nutrients to the Gulf through the Mississippi and Atchafalaya Rivers creates a perfect storm of exacerbated impacts in the Gulf of Mexico for years to come if changes are not made. As waters warm, experts predict that algae blooms will become more frequent, more intense, and occur in more bodies of water.  Moreover, as a result of the relationship between increased water temperature and nutrient load, it will become more difficult to contain blooms. The last red tide bloom in Florida lasted over 16 months (from November 2017 to February 2019), impacted Florida’s southwest, northwest and east coasts simultaneously, and was the worst red tide bloom that state has seen since 1953. There’s an opportunity now for Florida’s new governor to turn the tides – to rectify the head-in-the-sand, turn-the-other-cheek to polluters approach of his predecessor, and it seems he is working to promote research and monitoring of the causes of these phenomena. 

But this problem can’t be left to Florida (or Louisiana – or any of the Gulf states) alone, it’s not enough for downstream users to bear the burdens of its actions and its upstream neighbors’. We have to keep working together to promote more research and monitoring of likely causes, accountability and long-term solutions, which in turn can beneficially impact other areas of concern. For example, reduction in the use of pesticides and fertilizers makes farming more wildlife-friendly, countering the significant decline of pollinating insects across the world and thus sustaining long-term capacity for growth of our food supply, in addition to reducing the amount of nutrient-laden water to reach the coast – seems like a win-win to me!

So, while the red tide bloom that was starting to gain force during our time in Fort Myers hopefully will not amount to the same degree of harm the state experienced in the last, unprecedented red tide event, it certainly casts an uncertain and eerie shadow over Florida’s coast, local economies, wildlife and tourists this year. After experiencing a glimpse of the red tide impacts in person – and it truly was debilitating at the level we experienced, a walk outside was unpleasant and almost impossible without developing a crippling cough and shedding a tear for the loads of dead fish – it’s troubling to think of these events getting worse and more frequent. We hope that locals will continue to educate others about impacts, and that the politicians and experts can work together to address the sources and causes of harmful algae blooms in Florida and across the U.S. 

Florida’s Gulf coast is diverse, beautiful, and deserving of adequate attention and resources to protect its residents, wildlife, and local businesses. 

If you want to learn more about harmful algae blooms and red tide, or want to check out the status of your next Gulf coast vacation spot, check out the links to the right for more information and red tide status updates. Also, if you want to learn more about water quality for your local waterbodies near you, see if your area has a Waterkeeper protecting your beloved lakes, rivers and waterways and reach out to learn more about the threats to your water, and what you can do to protect what you love.