A new study by Mote Marine Laboratory in Sarasota has revealed a potential link between red tide algal blooms and long-term acidification of Florida’s estuaries.
Coastal residents of Florida are well aware of the harmful effects of red tide, ranging from skin, eye and throat irritation in humans to mass die-offs of marine life.
However, these immediate problems aren’t the only issues red tide can bring.
Ocean acidification occurs when carbon dioxide is absorbed into the water, forming carbonic acid and increasing the acidity of the water. The most common way this process happens is when atmospheric carbon dioxide, created by burning fossil fuels, dissolves into the sea and lowers the overall pH of the water.
But, lead researcher Emily Hall says her study has found that red tide blooms can cause localized biological acidification events as well.
“What's happening is we're seeing higher amounts of respiration. So just like we breathe in oxygen and out CO2, our phytoplankton species are kind of doing the opposite, right? They're breathing in CO2 and pushing out oxygen. But as they start to die, we see elevated respiration from microbial communities eating the die-off of those algal blooms.”
As the red tide decomposes, all the carbon dioxide that the algae has ingested goes back into the water, creating localized acidification events that degrade water quality and impact the health of marine life — even after red tide toxins are long gone.
Hall says that increased acidity in the water could spell even more danger for the future of Florida’s coral reef systems.
“A lot of our hard corals have a skeleton, and they use seawater chemistry to build that skeleton. With a more acidified ocean, it's going to actually start to dissolve some of those skeletons, and it doesn't allow new baby corals to be healthy enough to grow a good, strong skeleton the way they are accustomed to. And the same goes for our oysters, our scallops, our clams, those bivalves. we're seeing the same effect on those.”
Hall says that there’s more research to be done to achieve a full understanding of ocean acidification.
“The hope is to really try to understand what is happening before, during and after these bloom events. And it's not necessarily just looking at what causes or doesn't cause it. But more importantly, it's also understanding elevated heat, elevated exacerbated acidification, things that could also add to increasing harmful algal blooms that we have to look at as a global challenge.
While red tide looks like it’s here to stay, Hall adds that there’s actions that people can take to limit the amount of carbon dioxide that absorbs into the water.
“I always like to bring up keeping our backyards clean will help fight off some of these negative global effects. That would include things like as easy as planting native or Florida friendly vegetation in your backyard that reduces how much pesticides or fertilizers you need. So it is hard, it is a challenge to change global behavior, but locally, we can change those behaviors and have a cleaner, healthier bay or estuary. You have to kind of look at it in the big picture. And those little steps make a big difference.”
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