Hundreds Of Sharks Take Refuge From Red Tide In Longboat Key Canals
Hundreds of sharks in West Florida have headed inland to escape the deadly red tide that’s killed more than 600 tons of marine life in the region.
Different shark species, including bonnethead, blacktip, nurse and lemon sharks have been spotted darting through Longboat Key and into the canals of Buttonwood Harbor, far from their usual habitat.
‘You saw fins at first, just popping up,’ resident John Wagman told. ‘Just something I’d never seen in the canal before.’
Reports of marine predators in the bay started surfacing last week.
‘You could literally walk across the canal on the backs of the sharks in the water,’ resident Janelle Branowner told. ‘We don’t have healthy water in the bay right now.’
The sharks are invading the area because their usual habitats in Tampa Bay, Sarasota Bay and along the coast from Pasco to Sarasota Counties, have been infested with red tide, which is caused by unusually high blooms of the algae Karenia brevis.
The algae kills marine life by producing a potent toxin that affects their central nervous system.
It can also cause respiratory problems for humans, and has polluted the water, lowered oxygen levels and filled waterways with fish carcasses.
A red tide appears on Florida’s Gulf Coast about once a year, but these natural events are becoming more rampant, experts say, with climate change warming waters and allowing the microscopic algae population to flourish.
The red tide has been ‘patchy and persistent since December 2020,’ according to Mote Marine Labs, but the bloom has recently increased in severity.
Last week, the Florida Fish and Wildlife Commission (FFWC) reported massive fish kills in nine West Florida counties.
Five counties reported complaints by humans of respiratory distress related to red tide.
Water samples from Pinellas County, which includes St. Petersburg and Clearwater, show concentrations of red tide up to 17 times greater than the level considered high.
While scientists have yet to find a ‘smoking gun’ for the unusual blooms, Longboat Key is only a few miles from the abandoned Piney Point fertilizer plant, where a breach in April saw millions of gallons of toxic discharge dumped into Tampa Bay.
Hiding out in the canals is a stopgap measure, experts warn.
‘If it goes on long enough, they’re gonna run out of food and they’re gonna run out of energy,’ Jack Morris, senior biologist at Mote Marine Labs and Aquarium, told WFLA. ‘And unfortunately some of them, if not all of them, will die.’
The name ‘red tide’ comes from the fact that overgrowth of algae can cause the color of the water to turn red, as well as green or brown.
Earlier in July, marine biologists with Mote attempted a novel approach to tackling red tide: Partnering with Woods Hole Oceanographic Institute (WHOI) and the University of Central Florida, they sprayed wet clay to kill algae cells and toxins, a strategy used around the world to combat toxic similar blooms.
According to a statement from Mote, dry clay is mixed with seawater to create a ‘slurry’ that is hosed over the infected water.
As the dense clay particles sink, they combine with red tide cells—hopefully killing them as they bury them in the sediment on the seafloor.
‘This is just the first of what we hope will be several upcoming trials of clay flocculation on active blooms in the wild,’ WHOI scientist Don Anderson said in a statement.
‘What we learn here will help us better understand how conditions in Florida affect its success and how clay flocculation might be tailored to blooms of Karenia brevis, as well as other species of algae, here and elsewhere in the world.’
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