Red tide research shows economic impacts, possible solution to dead fish outbreaks
Ever wondered what to do with the millions of pounds of dead sea life that can wash ashore during a major red tide event?
Mike Parsons has.
The Florida Gulf Coast University professor and researcher spearheaded a study released last week that shows dead fish from red tide release nutrients could be used to develop compost.
"I think the main things we found out are that we confirmed that fish are a major source of nitrogen that can support red tide blooms," Parsons said. "We confirmed that composting can remove the toxins, and so we still need to see how effective it is as a fertilizer."
The research stemmed from a particularly nasty red tide event that lasted for more than a year but was especially bad during the summer of 2018.
Millions of pounds of dead sea life were removed from Lee County beaches. Sea turtles, dolphins and even a whale shark were among the casualties.
Local beaches and hotels were nearly barren, and the real estate and recreational fishing industries were hobbled by the toxic outbreak.
Once dead, the fish act as a nutrient source for red tide, which allows it to get even stronger.
"The red tide kills the fish to obtain more nutrients so you get more red tide, more toxins, more dead fish and basically it’s a feedback loop," Parsons said. "So if you remove the fish, you remove an important nutrient source."
Red tide (Karenia brevis) is found naturally in the Gulf of Mexico at background levels, but the organism can turn waters toxic when counts get above 100,000 cells per liter.
Fish kills are likely at that level.
Red tide also causes breathing difficulties in humans and mammals as the toxins become aerosolized.
Researchers say red tide outbreaks are stronger, more common and longer-lasting than they were just 50 years ago, likely due to human influences like farming and development.
Impacts from large blooms seem to be growing as well.
"It’s worth the investment to remove these fish," Parsons said. "So what’s the best way to deal with these fish? Don’t just get them to a landfill. Get them to a composting site. It looks like a good strategy. Now we need to implement it on a larger scale."
Lee County landfills were full of dead sea life in 2018, and most of the bloated carcasses were mixed in with trash and burned.
Harvesting the dead wildlife and turning it into a compost that could feed lawns and median could be a worthwhile business model, Parsons said.
That type of model would save taxpayers millions by having the private sector do the work.
"I think it’s a business opportunity because if you’re making this fish fertilizer, it would be organic because it would be natural and come from the ocean, and secondly all you would be doing would be returning the nutrients to the ocean," Parsons said.
Shelton Weeks, a professor and researcher in finance and economy at FGCU, said projects like this could help the Lee and Collier area better adapt to future blooms.
"I still like to think we're on the front end of this in terms of being able to collect really good data but we have enough to look at to gauge the overall impact of the event," Weeks said. "We used some basic economic data to estimate the potential lost revenue and that number did come out to be just over $19 million a month."
So, on average, the two counties lost $19 million a month when red tide counts were elevated, and most of the losses were due to fewer visitors, Weeks said.
"Hopefully we're at a point where we're getting a good enough handle on it that the next time we have a situation like this, people have more information for how to respond," Weeks said. "Having an event like that heightens awareness, and one outcome of that is next time we will be better equipped to get the economic data and get more precise measurements. Ultimately we're trying to help folks do a true cost-benefit analysis on cleanup, and that takes a lot of data."
Parsons said the clean-up efforts are well worth the cost.
"It’s pretty much a no-brainer to go and remove the fish from the water," Parsons said. "As long as you keep your fish costs under $19 million a month, you come out ahead."
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