Dec 11, 2025
For over a century, Florida’s coast has lived with harmful algal blooms, the infamous red tide. Once natural, occasional occurrences, these events have grown more intense and more frequent since the Industrial Revolution - another reminder that changes on land rarely stay on land.
Excess nutrients washing into rivers and watersheds act as fertilizer for the algae, feeding blooms that cloud the water, choke oxygen from the sea, and release toxins that burn the lungs of beachgoers just as they poison the gills of fish.
When a red tide bloom forms, the first thing to die is almost always the fish. Their bodies drift in by the thousands, floating atop of the water. The loss of fish means the loss of food, and for predators like sharks, it marks the beginning of a desperate migration.
Jasmin Graham is a marine biologist, educator, and leading voice in shark conservation. As a co-founder and President/CEO of Minorities in Shark Science (MISS), she works to expand access, representation, and equity in marine science while advancing research on sharks, skates, and rays. Her story recounts how concern for the wildlife in the ocean has fuelled her current research.
“Sharks sink when they die,” Jasmin explains. “So it’s incredibly hard to know how many we lose.”
She and her collaborators at Sarasota Bay wanted answers, so they tracked tagged sharks, watching their movements as blooms spread across the coast. The sharks did what any of us would do in a poisoned home; they fled. They skirted the edges of the bloom, dodging toxic waters like smoke from a wildfire.
“After two major algal events,” Jasmin recalls, “the sharks didn’t return. We had to ask: did they leave… or did they die?”
The Toxin That Lingers in Bodies: Shark, Sawfish, Human
Even those that escape the bloom carry its mark.
Red tide produces brevetoxin, a potent neurotoxin that we already know accumulates in shellfish and fish, and sickens humans who eat them. But sharks, predators who feed on contaminated prey, store the toxin as well.
Researchers are now asking the question:
What happens to a shark with brevetoxin in its system? Similar neurotoxins from algae have led to symptoms like that of “spinning disease” displayed in the critically endangered smalltooth sawfish and other predators in the Florida Keys in recent years - disorientation, neurological damage, death. Scientists still don’t know if brevetoxin exposure can cause similar symptoms, but the parallels are alarming.
Even if a shark is born far from a bloom, even if a shark leaves the bloom behind, it can still be exposed through its food and build up in its body. This leads us to question our own health, too. If consuming the fish is damaging to sharks, it could also be damaging to humans?
Communities Feel the Tide Too
When red tide strikes, it doesn’t just shut down ecosystems and damage our health, it shuts down economies. Empty beaches. Closed fisheries. Canceled charters.
The water that supports ocean life also supports families, and when that water turns toxic, livelihoods are the next to suffer.
That community-level struggle is why MISS and its partners are invested not just in research, but in education and watershed stewardship. If nutrient pollution is the spark that fuels red tide, then mitigation must begin long before water ever reaches the coast.
“This effort starts upstream,” Jasmin emphasizes. “We need people to understand how their actions, potentially miles from the ocean, still shape its health.”
Together with programs like the Tampa Bay Estuary Program, advocates are bringing MISS’ watershed curriculum into schools, working to help young people see the interconnectedness that adults often overlook. After all, solving the problem starts with understanding it.
Can Sharks Heal Themselves?
New experiments now ask whether sharks can eliminate brevetoxin from their bodies. Has evolution given them a tool to survive the crisis we’ve accelerated? If sharks can recover on their own when living in safer conditions, all we need to do is clean and protect their waters.
If they can’t, then the least we can do is stop adding to the crisis again and again by cleaning up our environment and mitigating these red tide blooms.
The water, Jasmin reminds us, connects everything.The runoff in our streets and farms, the health of our fish, the fate of our sharks, the air we breathe on the beach. It affects our jobs, our recreation, our food, our future.
We are not separate from the ecosystem.
We are one of its threads. Understanding how our ecosystems are changing in relation to our behaviours allows us to take informed action. With the knowledge we have now, what action do we want to take here?
This story was shared with permission. The storyteller maintained editorial review rights over their narrative.
