Featured Image Credit: FWC
By: Sarah Sharkey
It’s the summer of 2018. Ordinarily pristine and busy Sanibel Island has a surprise guest.
A dead whale shark has washed up on the shore, accompanied by hundreds of fish. This
endangered shark, like other animals in the ocean including turtles and manatees, was a victim of
a problem decades in the making.
Harmful Algal Blooms (HABs), also known as red tides, are a naturally occurring event
in warm, shallow water bodies all over the world. Certain species of microscopic plants called
phytoplankton produce very low concentrations of toxins. However, when fed by nutrients and
warm temperatures, these plants bloom and create levels of toxins that have a harmful effect on
wildlife and people.
A few hundred dead fish is standard for Florida’s Gulf coast during a HAB. This season’s
bloom that began in October is unprecedented. This whale shark, over 400 turtles, 10 manatees,
and thousands of fish and marine invertebrates have been afflicted by this deadly neurotoxin.
Humans are also feeling the effects. At 10,000 algal cells per liter, humans can start to come
down with respiratory and vision problems. How does this bloom stack up? It’s well over
1,000,000 cells per liter. Fortunately, if humans stay away from affected water and avoid eating
seafood from that area of the coast, we can escape these harmful effects. The wildlife that make a
life beneath the waves do not have that option.
A catalyst in this record-breaking HAB is the release of nutrient-concentrated water from
Lake Okeechobee. Historically, this Lake flowed south. After mass migrations to the sunshine
state, the Army Corps of engineers built a dike to trap the water and dry up land for sugar fields
and development. The farms that surround the Lake pile fertilizer on their crops that inevitability
washes into it. The shallow, warm, nutrient-loaded lake is a perfect blooming ground for the
deadly phytoplankton to multiply.
After a heavy rainy season, the polluted water is sent east and west to prevent sugar cane
field flooding, carrying the toxins with it. Unfortunately, the two rivers that carry the water lack
the filtering vegetation that lies just south of Lake Okeechobee. Without a filtering mechanism in
place, all we can do is sit and wait for cooler weather to free the Gulf from this green chokehold.
You can check the status of HABs throughout Florida by visiting the Florida Fish and
Wildlife Conservation Commission’s Red Tide Status Report. If you live in Florida, consider
writing to your elected officials and urge them to take action against this happening in the future.
Filtering the water and restoring the natural flow are some ways to prevent HABs from creating
economic and environmental ruin for this place where we live, work, and play.