By Andy Mele, Special to The Islander
As 150 guests at the Suncoast Waterkeeper Brunch for the Bay learned March 3, the red tide bloom in 2018 was not a natural occurrence.
The determining factor in today’s red tides, after all variables are accounted for, is human-induced nutrient pollution — primarily nitrates and phosphates. Nutrients are not merely a marginal contributor, as some institutions and elected officials would like us to believe.
True, Karenia brevis, the toxic alga that populates the lethal blooms we call red tide is a naturally occurring organism. It is found in waters around the globe.
And, yes, red tides have been documented since the arrival of Europeans to Florida’s shore. But there is a difference between the naturally occurring red tides and the rapidly growing red tides we have endured for decades.
About Karenia brevis
Karenia brevis is also known as red tide when its numbers become higher than 1,000 cells per liter. K.brevis emits brevetoxins that can become airborne in water spray and wind. At concentrations above 10,000 cells/liter, red tide can cause respiratory symptoms in humans. Above 50,000 cells per liter, fish mortality begins to occur. Above 1,000,000 cells/liter, discoloration of the water can be seen. Concentrations as high as 50,000,000 cells/liter were observed during the 2018 red tide event.
Larry Brand, Ph.D. and a research scientist at the University of Miami, was the featured speaker at Suncoast Waterkeeper’s annual brunch at the Bradenton Yacht Club in Palmetto.
Brand told his audience there is a fifteenfold increase in K. brevis concentrations that is contributing to today’s mega-blooms. After accounting for geological and geographical contributions to red tide, Brand said, “The only remaining variable that has increased enough to account for it is us.”
Brand explained some of the complexities of Florida’s red tide. Plants — and algae are plants — require 16 parts nitrogen to one part phosphorus. Where that 16N:1P ratio is found, there can be a natural red tide bloom.
The waters on the East Coast of Florida — where the St. Lucie Canal empties Lake Okeechobee discharges thick with toxic blue-green algae — are dominated by limestone deposits and are naturally rich in nitrogen. Hence, phosphorus is required to provide the optimum 16:1 nutrient that drives algal growth. No phosphorus, no algae. Phosphorus is relatively scarce on the East Coast.
On the southwest Gulf Coast, however, the opposite circumstances prevail. Because of massive natural phosphate formations underlying west-central Florida and in the Gulf of Mexico, the coastal waters are rich in phosphorus from a variety of inputs, including phosphate mine drainage. Here, algae need nitrogen to stimulate growth. No nitrogen, no algae. It’s called “nitrogen-limited.”
However, when Lake Okeechobee’s nitrogen-rich blue-green algae enters the system from the Caloosahatchee River, the conditions for explosive growth are met.
Brand lists four principal sources of nitrogen: animal waste, crop fertilizer, stormwater runoff and illegal sewage discharges. All have increased exponentially since the 1950s along with Florida’s population and development, when the first sample run was conducted by FWC. In the 1950s, less than 10 percent of the Florida coastline was developed, while the remainder was woodlands, grasslands and wetlands. Today, more than 90 percent is developed and we’re flushing pollutants into the bays and Gulf.
Agricultural sources — animal waste and fertilizer — are the major causes of intense algal blooms in Lake Okeechobee. They are transported down the Kissimmee River, and pumped north from sugar cane fields south of the lake. The other two sources — stormwater and sewage — supply a steady diet of nutrients for red tide as it expands up and down the Gulf Coast.
Aside from people with respiratory symptoms who may suffer chronic asthma or COPD, the effects of K. brevis are immediately noticeable, leading people to leave the area, although no long-term or acute effects are known. The only known human fatalities associated with red tide have been from shellfish poisoning. Shellfish filter water through their gills to extract food and oxygen and, as K. brevis cells accumulate in shellfish, they can be fatal if eaten.
Blue-green algae, on the other hand, which is consumed by fish and shellfish, are suspected of having long-term impacts, specifically ALS or Lou Gehrig’s disease, Alzheimer’s and Parkinson’s, without short-term impacts to warn of exposure. The correlations between algae and disease are still being studied, but an environmental toxin, beta-methylamino-L-alanine or BMAA, is found in both victims of the diseases and the blue-green algae.
BMAA appears to provide a causative link.
And BMAA has been documented in almost all shrimp and species of fish from the areas of the red tide bloom.
As a general caution, Brand suggested not consuming any seafood from areas impacted by red tide for several months after the event has subsided.
Data sets for 1954-63 are regarded as baseline “naturally-occurring” red tide, approximately what Hernando de Soto or Ponce de Leon might have seen in the 1500s — neither a threat to tourism nor an apocalyptic killer of fish and marine mammals.
But today’s conditions are both, according to Brand, and it’s worsening.
The ozonators, bubblers and clay sprinklers being touted by Mote Marine Laboratory and some elected officials as fixes are unproven, wildly expensive and cannot be scaled up to levels needed to treat the coastline. Brand says they appear to be strategies for developing revenue from wealthy canal homeowners, and cannot be taken seriously as solutions to red tide.
He said it, and Suncoast Waterkeeper has been saying it since last summer: the only practical, meaningful and affordable solution is to stop the nutrient pollution at its source. And its true source is not at a dairy farm or a sugar cane field. It is in Tallahassee.
Here’s the Waterkeeper solution to red tide.
Florida urgently needs:
• Numeric, enforceable water quality standards and the FDEP staff and budget to enforce them.
• Common-sense limits on development.
• No more phosphate mining.
• Elected officials who understand that as the water goes, so goes Florida.
• A comprehensive water and aquifer management program, including conservation measures, pricing and limits.
Brand and Suncoast Waterkeeper maintain that without action and change, there is little chance for improvement and there’s a strong prospect the state’s water crisis will worsen.
Andy Mele, of Suncoast Waterkeeper, is an advocate for a better environment and responsible development in Manatee County. He is former executive director of a major Hudson River environmental group that was instrumental in forcing General Electric to remove 300,000 pounds of toxic PCBs from the river. He authored “Polluting for Pleasure,” the book that rendered two-stroke outboard motors all but extinct, keeping millions of gallons of oil and gasoline from U.S. waterways every year. He can be reached at firstname.lastname@example.org.