Here's What's Going on With the Ongoing Fish Kill in Biscayne Bay

The Frost Science team deploys air pumps into Biscayne Bay.
The Frost Science team deploys air pumps into Biscayne Bay.
Photo courtesy of Frost Science
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It has been almost two weeks since dead fish started floating to the surface of Biscayne Bay.

Since August 10, scientists and environmentalists have been trying to figure out why animals in the bay are dying, while making Hail Mary efforts to save those that are trying to survive. Low oxygen levels in the water have made it hard for fish and other marine life to continue living their underwater lives as usual. And without enough oxygen to breathe, the animals can suffocate and die.

"It's much like would happen to us if we were deprived of oxygen, and unfortunately similar to the COVID situation," says Andy Dehart, vice president of animal husbandry at the Frost Museum of Science. "In a way, it's a fish pandemic."

Dehart and other experts at Frost Science have been part of the fight to save the animals of Biscayne Bay. Last week, the team was dispatched to an area near the Pelican Harbor Seabird Station off the 79th Street Causeway, where hundreds of stingrays, pufferfish, and other species were seen gasping for air. Dehart says the oxygenation levels were about 6 percent at the bottom and between 20 and 30 percent at the surface, although he says some water samples taken elsewhere in the bay measured as low as 0 percent.

"As an animal-husbandry person, I get extremely worried about these animals at lower than 50 percent, and lower than 30 percent is cause for great alarm," he says.

Frost Science was able to set up several air pumps to put more oxygen in the water — something Dehart says is an emergency measure, but not a terribly effective one.

"It's kind of like dropping a thimble's worth of water onto a forest fire," he says. "We tried to help out how we could."

Fireboats from Miami and Miami Beach have also been deployed to spray their hoses into the bay, disrupting the water and creating more oxygen.

Dehart says that while thousands of dead fish have bobbed up to the surface of the bay, an unknown number have died at the bottom.

"A lot of the fish that are dying are actually just sinking, so the toll is a lot greater than what we're seeing at the surface," he says.

Once dead, those fish breed bacteria, which then suck even more oxygen out of the water. Over the weekend, the City of Miami and Fertile Earth Worm Farm set up composting bins at several waterfront parks to encourage volunteers to scoop the dead fish out of the water.

Miami Waterkeeper, a clean-water advocacy organization that has been leading the response, said in an Instagram post yesterday that water samples tested by the Florida Fish and Wildlife Conservation Commission show the fish kill was caused by pollution in the bay.

Miami Waterkeeper executive director Rachel Silverstein tells New Times there are four main sources of pollution in Biscayne Bay: sewer leaks, septic-tank leaks, stormwater runoff, and fertilizer.

The sewer, septic, and stormwater pollution contains bacteria, which deprive the bay of oxygen. The stormwater runoff often also contains nutrients from fertilizer. Silverstein says that when those nitrogen and phosphorous nutrients get into the bay, they breed algae and fertilize the blooms already growing. The algae blooms also consume more oxygen from the water, leaving less for the native plants and animals.

At a press conference Tuesday, Miami Waterkeeper attorney Kelly Cox pointed out that nutrient levels in the bay have been elevated for the past 20 years.

"Biscayne Bay has been designated as an impaired water body for several years," she said. "The fish kill is a symptom of a larger disease that Biscayne Bay is facing."

Miami City Commissioner Ken Russell said "hundreds of thousands of gallons" of raw sewage have leaked into the bay for years. He told reporters that rising water temperatures caused by climate change are not solely to blame.

"This was a cocktail that's been waiting for the heat to trigger, but it doesn't allow us to say, 'This is our new normal of the environment,' that every summer, fish are going to die just because of the heat," Russell said. "This is not just because of the heat — the heat is the trigger for the cocktail that we've left there."

The commissioner urged residents to vote for a county mayor who will prioritize the health of Biscayne Bay.

"We've had enough of this shit. Because that is what's in the water…. We need to fix a broken infrastructure in addition to all these other things that we're doing, and that only comes from massive leadership at the county level," he said.

As of late, the fish kill has been mostly contained to the northern part of Biscayne Bay, between the 79th Street and Julia Tuttle causeways, although Silverstein says the danger appears to have moved north toward Miami Shores. 

Dehartat says the fish kill event presents a problem with no easy fixes.

"The helpless feeling, just like in red tides, is there's not a lot we can do on a big scale to help this immediate problem, but there's a lot we can do to keep learning from this, even in our own backyards, with thinking green," he says. "It, unfortunately, might be a wake-up call more than a 'How can we immediately Band-Aid this?'"

But Miami Waterkeeper says there are some things the average resident can do to help — the nonprofit is asking residents to report any sightings of dead fish, gasping fish, or pollution by emailing hello@miamiwaterkeeper.org with photos, videos, the date, the time, and the location. The group is also recruiting volunteers for its 1000 Eyes on the Water Rapid Response Team and accepting donations for supplies and equipment.

And if you want to learn even more about what's going on in Biscayne Bay, Silverstein will be hosting a Q&A session tonight on Instagram Live at 6 p.m. on the Miami Waterkeeper account.

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