I spent the morning walking along the St Pete FL waterfront near the Pier. Usually, I see lots of shorebirds fishing, the occasional dolphin, and various fishies swimming along. Today, instead, I saw a lot of dead fish floating belly-up.
As some folks may recall, about two months ago there was a spill in an artificial pond at the Piney Point phosphate plant near the mouth of Tampa Bay. A leaky liner dumped 215 million gallons of phosphate-rich wastewater into the Bay, causing a large fish kill from the acidic water.
Now, Tampa Bay is in the midst of a severe Red Tide algal bloom that is resulting in another massive fish kill. And while there is as of yet no definitive link between the two events, everybody has their suspicions.
“Red Tide” is caused by microorganisms that live in seawater, particularly in shallow warm waters in bays and estuaries. These include protozoans, phytoplankton, diatoms and dinoflagellates. Normally harmless and present in only small quantities, these organisms can suddenly undergo a population explosion known as a “bloom”, especially when a large amount of nutrients enter the water. This can happen when natural upwellings bring a large dose of nutrients to the surface, or when heavy rains wash a lot of lawn fertilizer into the Bay. It can also happen when, say, a phosphate company leaks a shit-ton of fertilizer waste out into the Bay.
As they expand, the microorganisms form vast colonies in the water, often appearing as a splotch of red or orange slime on the surface. Hence, Red Tide. In Florida, the most common cause of Red Tide is the dinoflagellate Karenia brevis.
The danger comes from the natural neurotoxins produced by these microorganisms. Known as brevetoxins, they are a natural defense which helps protect the dinoflagellate from microscopic predators. But during a Red Tide bloom, there are so many toxin-containing organisms in the water that they can be lethal to plankton-feeding fish and filter-feeding marine invertebrates. The poisons then travel up the food chain from small fish and shellfish to larger fish, sea turtles, and shorebirds, sometimes killing even large animals like manatees and dolphins. The toxins can also be dangerous to humans who ingest contaminated water while swimming or who eat seafoods which contain the toxins, and when carried on the wind in tiny water droplets the toxins can also cause irritation in the airways and lungs.
Around four or five weeks ago, scattered Red Tide blooms began appearing in Tampa Bay and along the nearby Gulf of Mexico. Since then the blooms have grown and conglomerated, and over the past week or so the resulting fish kill has become massive. City officials were forced to collect the dead and rotting fish to dispose of them—an effort that needs to be renewed each day as more and more fish continue to die. So far, over 670 tons (and counting) of dead fish have reportedly been scooped out of Tampa Bay and the Gulf Coast. As I can attest, the aroma of rotted fish can be detected over a block away from the shoreline, and thousands of dead corpses, bloated by decomposition, can be seen floating on the Bay’s water or washed up on shore.
Tampa Bay has had Red Tides before. The last serious one was in 2018; it lasted over a year, affected over 100 miles of coastline, intermittently closed the area’s tourist beaches, and also crippled the local fishing industry. State officials are already afraid that this one will be worse.
Testing is currently being done to see if the chemical signatures of the phosphate nutrients in the water which are feeding the dinoflagellate bloom match those that were released in the Piney Point leak. Meanwhile, the fish kill here has been characterized by state fish and wildlife officials as a “disaster”, and the Florida Fish and Wildlife Conservation Commission is asking the public to report any sick or dead manatees, sea turtles, or dolphins.
And it’s not over yet.
Some photos.