Coastal Insecurity Report: Florida Red Tide & Nutrient Pollution in North Carolina

By Miles Bolton

Late Afternoon by the Sea (The Red Wave)- Joaquín Clausell. Photo Credit: WikiCommons

This Hurricane Season has had a different tone than past hurricane seasons as there’s an increasing number of news stories discussing nutrient pollution and coastal habitat destruction as opposed to focusing exclusively on property damage and the human toll. In North Carolina, Hurricane Florence helped unleash vast reserves of hog feces from commercial hog farms as well as toxic coal ash from power plants into coastal areas. The environmental repercussions of this fecal onslaught on North Carolina’s coastal habitats are up for speculation, but it can be reasonably assumed that heightened nutrient loads could lead to eutrophication and potentially harmful algal blooms. In Florida, the growing Red Tide that has plagued Florida’s shorelines since last November has been declared a state of emergency by Florida Gov. Rick Scott.

​Since the Red Tides debut last November, it has annexed nearly 145 miles of Florida coastline, according to the Florida Fish and Wildlife Conservation Commission (FWC), and killed 267 tons of a wide manner of marine life that have washed up on shore as result. The washed up marine beings creating an unbearable stench for Florida’s many tourists who have had to flee its beaches for it’s odor. At least that’s how the Red Tides effect is often presented in the media, with the generic takeaway “How will the Red Tide affect Florida’s tourism?”. The red tide undeniably will have a profound impact on Florida’s tourism industry there’s no doubt, but the discussion as to how it will affect the fishing industry, aquaculture, and locals or what the root causes of the red tide are has been limited.

Less aesthetically pleasing depiction of Red Tide. Photo Credit: WikiCommons


Karenia brevis, the red algae species of interest, is a dinoflagellate algae endemic to the Gulf of Mexico and the coasts of Florida and North Carolina. Its populations explode when there is a change in nutrient concentrations (ex: nitrogen, phosphorous) in the surrounding water resulting in what is known as a red tide. During red tides, Karenia brevis releases a potent form of neurotoxins called brevetoxins. Brevetoxins accumulate in the tissue of fish and other marine organisms binding to voltage-gated sodium channels in nerve cells, interfering with basic neurological functions and can lead to paralytic shellfish poisoning, fish kills, human health problems, and even crash fisheries. ​


Now while it is true that Red Tides in Florida are an annual, natural occurrence,  the duration and caliber of this Red Tide isn’t a natural occurrence by any means. The Red Tides are fueled by a number of factors such as warmer waters which facilitate the growth of red tides, offshore wind patterns that pushed the tide towards the shore, and heavy fertilizer runoff from Hurricane Irma last year. For context in regards to nutrient pollution, Florida consumes the 4th most fertilizer in the U.S, 30% of the population uses septic systems (they leak), and the Florida peninsula is supported on a foundation of porous limestone that makes it easy for nutrients to accumulate in the watershed. Not to mention nutrient inputs running off from Florida’s sugar industry, accounts for almost half of the U.S’s sugarcane production, and phosphate mining. ​

Dead fish floating belly up in Karenia Brevis (Red Tide) Photo Credit: Photo for Washington Post by Eve Edelheit


Thus far a few potential solutions have been proposed as part of an effort to combat the Red Tide though none so far have addressed the root causes of the epidemic. One solution involves pulling in Red Tide infested waters from canals into 25,000 gallon tanks where the water would be treated with ozone and pumped back into the ocean. This method was developed by scientists at Mote Marine Laboratory (Sarasota, FL), Richard Pierce, a senior scientist and program manager for ecotoxicology at the lab, compared the process to the process used to cleanse aquariums and swimming pools.

A few questions arise when thinking of the potential side effects and limitations of this solution. First off, while the ozone would be effective at killing off Karenia brevis what else would it kill off and how much ozone would enter coastal areas when the water is pumped back out? Secondly given the capital needed to implement this project on a large scale, how expensive and how sustainable is this method? Thirdly how will this method prevent future Red Tide epidemics? Everyone is entitled to their own opinion but personally this method simply sounds like a way for this lab to profit from the Red Tide events rather than to comprehensively combat the root causes of Red Tide to mitigate future outbreaks.  

Other scientists are investigating the introduction of diatoms (microalgae), which would compete with Karenia brevis for nutrients, and types of macroalgae that’d relate chemicals to inhibit the growth of Red Tide. This solution makes more scientific sense and has a lesser risk of harmful side effects; however it’s difficult to get behind any solution that doesn’t address nutrient pollution. Though, people are still debating the true cause of the Red Tide, nutrient pollution is an associated cause of a large percentage of algal blooms and Florida releases an alarming amount of nutrients into its coastal areas. Seems like a relatively straightforward cause and effect relationship to me. You can't prevent future Red Tides without reducing nutrient inputs into waterways. 

Flashback to Hurricane Floyd 1999 impact on North Carolina. Photo Credit: Alan Marler/AP


Much of the Southeastern U.S coast was hit hard by Hurricane Florence devastating countless communities, however North Carolina could potentially be one of the most affected states in the long term due to nutrient loads released into waterways by the storm. There were two significant inputs of pollution from Duke Energy power plants and Industrial Hog Farms.

Despite maintaining that their method of containing toxic coal ash in earthern pits mixed with water is safe, one of Duke Energy’s toxic coal ash lakes was breached during Florence and the coal ash entered the Cape Fear river. The largest toxic coal ash spill on record happened in 2008 in Kingston, Tennessee where a breached pond released 1.1 billion gallons of coal ash. The cleanup cost more than $1 billion dollars. In North Carolina’s case, Duke Energy reported that approximately 2000 cubic yards of toxic coal ash were released, with conversions this accounts for 403,948 gallons of toxic coal ash. Coal ash, the after product after power plants burn coal to generate electricity, contains heavy metals that are closely linked to respiratory illnesses and cancer. North Carolina’s hog farms delivered a heavy blow to their coastal areas during Hurricane Florence when massive amounts of hog waste were released when floodwaters breached hog lagoons (man-made lagoons to store pig feces). Due to Hurricane Florence, 110 hog lagoons in North Carolina have either released pig feces or are at a high risk of doing so. For context, North Carolina has a population of 9.7 million pigs which produce 10 billion gallons of manure annually, which equates to 500 times the annual waste produced by the population of Washington D.C. Although I confess that I'm an enthusiastic consumer of pork, it is an undeniably environmentally costly industry. North Carolina, after Hurricane Floyd in 1999, dealt with this situation before where hog lagoons in eastern NC released a large influx of pig feces into waterways creating algal blooms, mass fish die-offs, and elevated levels of nitrogen and phosphorous. They haven’t released any numbers detailing how much hog waste has been released yet but one can assume that there will be similar consequences following the coupled input of hog waste and toxic coal ash into coastal areas.

Hog Farms flooded during Hurricane Florence near Trenton, N.C. Photo Credit: Steve Helber/AP


In Florida’s case it seems to be abundantly obvious that the occurrence of Red Tides and the deterioration of their coastal ecosystems as result will continue unless something is done to reduce the amount of nutrients running off into waterways. Neither an ozone pump nor newly introduced algal species are adequate solutions to the Florida Red Tide. The Red Tide is merely a symptom of sustained nutrient pollution in Florida and until these nutrient inputs are dealt with it will be difficult to improve the health of coastal communities. The Red Tide will have significant consequences for many Floridian industries, which will force Florida’s government to deal with the Red Tide one way or another with the fear of losing voters if it is not remedied. North Carolina is not in as dire a situation as Florida is in at the moment, but based on past events (Hurricane Floyd) showing the effects of releasing hog waste into waterways there is plenty of reason for concern. Time will tell to see how the state handles the recent outpouring of hog waste and toxic coal ash as the after effects remain to be seen. North Carolina residents may be wary at the states willingness to take effective environmental measures to combat nutrient pollution as the state recently banned studies on sea level rise. Fingers crossed for now.

Disclaimer: Although red tide should be spelled with lower case letters, the extent of the Florida Red Tide demands greater emphasis.. and capital letters.



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