What Is Red Tide?
The toxic red tide has hit Florida’s beaches since last year, and it’s especially bad right now. Our friends at Earther cover this topic in depth, but if you’re wondering what a red tide is and why everyone is talking about it, we have the answers to your basic questions.
What is red tide and why is it called that?
Red Tide is actually a collection of microscopic creatures floating in water. The ocean is always full of microbes, but when we talk about red tide, we mean certain species that sometimes appear red and can fill the water with their natural toxins. The Florida red tide is the result of the activity of a species called Karenia brevis .
Each K. brevis is a separate cage with a small tail, which it uses to swim. It can make food from sunlight, just like plants, which is why it is considered a type of algae. And since it is a tiny living thing in the ocean, it is also a species of plankton. Under the microscope, K. brevis is brownish in color, but when the sea water is full of them, we can see water with a red and sometimes yellow or brown tint .
Other harmless algae can also color the water in an interesting color, so instead of “red tide” it is considered more accurate to speak of “harmful algae blooms.”
What makes it bloom?
An algae bloom is a large population of algae – billions of tiny creatures that fill seawater in a specific area. Under suitable conditions, including a large amount of nutrients in the water, algae will multiply. Imagine that every time you walk into an unlimited food buffet, you can just have a bunch of babies for your whole family to fill the restaurant and gobble up everything inside.
K. brevis blooms in the ocean every year and is washed out on the shores of Florida’s Gulf Coast. This is not the kind of bloom associated with fertilizer runoff – this is another bloom that is hitting Florida right now (yes, they have two). But a red tide bloom can fuel another, and fertilizers can play a role. However, it is usually other factors, including ocean currents, that cause red tides to bloom in Florida waters each year. K. brevis feeds on carbon dioxide and enjoys warm water, so climate change may be one of the reasons why this year’s bloom has been particularly bad.
This year’s bloom started in October last year and did not disappear this spring as usual. There is a good chance it will get worse from here as the red tide season begins again.
How toxic is it actually?
K. brevis produces a neurotoxin (a poison that damages the nerves and brain) called brevetoxin . This toxin can kill animals, including fish and birds. Manatees and sea turtles were also found dead during the recent red tide.
People who eat shellfish contaminated with the toxin can get neurotoxic shellfish poisoning , so it is important not to collect or eat shellfish in areas affected by the red tide. The toxin is odorless, colorless and tasteless and does not degrade when cooking. Symptoms include nausea, vomiting, and diarrhea, and tingling or numbness of the face, hands, and feet.
We can also breathe in toxin. When waves filled with algae crash on the beach, they can destroy some of the algae cells and send their toxins into the air. People with asthma or other lung conditions are at greatest risk, but healthy people can also be affected. You will notice shortness of breath and possibly eye irritation.
On beaches affected by the red tide, a sign often appears warning you to breathe in the area, especially if you have lung conditions such as asthma. The water can be full of dead fish, so you don’t want to swim in it anyway.
Did the hurricane make it better or worse?
It’s too early to say for sure, but NBC reports that there is a decrease in the number of K. brevis in water samples in many areas. The hurricane may have mixed the water in the ocean “like a blender,” diluting the body of the red tide, according to one biologist with whom they spoke.
On the other hand, hurricane-induced flooding can push nutrients out into the sea for K. brevis to feed on. The Smithsonian reports that the red tide intensified after four hurricanes hit Florida in 2004, but also that Hurricane Katrina was followed by a decrease in the number of red tides. So we’ll have to wait and see.