A boat sails through a deepening algae bloom across the Caloosahatchee River
Florida Algae Crisis:
What's the difference between red tide and blue-green algae?
A Goliath grouper, killed by toxic algae, on the shore in Sanibel
Photo: Joe Raedle/Getty
A raging algae bloom is clogging Florida's beaches impacting all forms of marine life off of southwest Florida. The result is dead fish, dead turtles, and dead manatees, with no end in sight. And it's not just wildlife that's suffering: The toxic algae and red tide endanger the health of local communities and devastate coastal economies that depend on beach going tourists.
The bloom along the Florida coast stretches 100 miles from Sarasota County to Collier County. It has affected the coastline in different ways and areas for the past nine months. Today, the algal load in the water was very concentrated, at millions of cells per liter of ocean water. A low concentration is ~1,000 cells per liter.
Southwest Florida is experiencing two types of algal blooms, both in the Gulf of Mexico and in freshwater basins like the Caloosahatchee River to Lake Okechoobee to St. Lucie River.
Red tide is not Florida's only environmental disaster: Cyanobacteria is taking over Florida's freshwaters, clogging canals and smelling up the air. Unrelenting development is the cause for cyanobacteria proliferation. Photo: Ben Depp.
The red tide, formally known as Karenia brevis, was already in Gulf of Mexico waters at the beginning of 2018. It is an often recurring bloom that typically starts 10 to 40 miles offshore. Red tide isn't always red, either. It can range in color from brown to red to black.
Blue-green algae, or cyanobacteria, is a more recent bloom affecting fresh waters in Florida. This algae more closely conforms in color to its name.
With both algae blooming in the area at the same time it is hard for some to tell the difference between the two. The results are the same, however. Dead fish, dead marine mammals, dead sea turtles, and dying ecosystems.
This dead loggerhead sea turtle is just one of a record number of turtle deaths during the ongoing Karenia brevis algae bloom. Wildlife often ingest the toxin, which attacks their nervous system with often fatal results.
Photo: Ben Depp
The cause is clear: Development.
Who to blame?
Blame the Governor of Florida, Rick Scott, for runaway development and the systematic dismantling of Florida's environmental safeguarding apparatus. For years, Rick Scott has been slashing protections for Florida's environment—and now, our coastlines and communities are paying the price. Rick Scott puts special interests ahead of the Florida environment. And now he wants to take his anti-environment agenda to Washington as Senator. Vote NO to Rick Scott for Senate!
But know that the cause is also all of us. Every Floridian is contributing to runoff and nutrient loading in Florida's waters and the Gulf of Mexico and both ecosystems are dying.
Phosphorus and nitrogen poison Florida's waters during each rainfall, running off agricultural operations, fertilized landscapes, urban areas, and septic systems. The poison runoff triggers algae outbreaks, which foul Florida's beaches, lakes, rivers, and springs in increasing quantities each year. 2018 is perhaps the worst such outbreak and in 2018 the worst of the worst is along Florida's heavily developed southwest coast.
Toxic algae blooms are not limited to the southwest coast of Florida. Runoff from Lake Okeechobee causes similar blooms, like this one near Stuart in 2016, on Florida's east coast.
Habitat
The most notable difference in the two algae is the type of water the algae prefer. Red tide does not fare well in lower salinity waters. Most red tide blooms occur in the Gulf of Mexico, but it can make its way into estuaries and bays.
Blue-green algae prefers fresh waters. Blooms most naturally occur in lakes and rivers.
Official Causes
Another big distinction is the cause of the blooms. Karenia brevis is naturally occurring and the cause of the blooms are unknown. However once red tide makes it to local waters, growth is enhanced by agricultural and urban runoff.
Blue-green algae blooms have are more directly caused by agricultural and urban runoff. Nutrient pollution encourages the growth of cyanobacteria.
Human Effects
Once waves break open the cells of red tide, toxins are released into the atmosphere causing respiratory issues. These toxins also accumulate in oysters and clams leading to Neurotoxic Shellfish Poisoning in humans.
Swimming in red tide is not smart, but likely relatively safe. Personally I would not care to swim in water full of dead fish.
Blue-green algae contains a variety of toxins directly affecting humans. Ingesting cyanobacteria in water can lead to vomiting and even acute liver failure. Microcystins in the algae (toxins) can also cause skin irritations.
Red Tide kills a whale shark off Sanibel Island
Marine Life EffectsDeath. Brevetoxins in red tide attack the central nervous system of aquatic life. These toxins cause death.
Blue-green algae blooms grow large enough to block the sun killing submerged plant life. The algae also reduce the oxygen content in waters, killing fish and other marine life.