The term red tide is used to describe a harmful algal bloom, which happens when algae grows out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds. The algae is so numerous that the bloom often turns the water red, which is why the event is dubbed ‘red tide.’ The toxins produced by K. brevis, a species found in the Gulf Coast, attack the nervous systems of wildlife when accidentally ingested and the fumes given off can affect people's’ breathing.
However, red tide events are naturally occurring events. Reports of massive fish kills and aggravating fumes go back centuries in different parts of the world. Florida’s Gulf Coast does typically experience a red tide event every summer to some extent. However, this year’s occurrence, which began in October of 2017, has been particularly devastating. The question is why? We know that this species of algae, K. brevis, is always present in the water columns off of Florida’s Gulf Coast. So what is the reason behind this year’s intense and deadly algal bloom?
One explanation could be the amount of agricultural runoff coming from the land. Typically, algal blooms will occur offshore but travel inland via water currents and winds. Then, when the algae meets the nutrient-rich coastline provided by runoff, we see dramatic algae blooms. Basically, the algae population has a steady food supply which could account for it to continue blooming and a red tide event to occur if harmful toxins are produced.
Researchers have also documented significant red tide events after major hurricane years in Florida. When all the rainwaters flood the land, they eventually bring nutrient-rich runoff back into the Gulf resulting in red tides, which occurred in both 2004 and 2005. Hurricane Irma hit Florida in 2017 which brought massive amounts of runoff back into the ocean. Therefore, the red tide the state is experiencing now would be consistent with this theory. Also with climate change scientists predicting more frequent and intense storms, more severe red tide events could continue to occur in the future.
Either way though, solutions are needed and there is one interesting idea in the works for mitigating this problem. Mote Marine Laboratory has created a device called the “Ozone Treatment System” that can filter 300 gallons of water per minute and is designed to break down toxins in the water by injecting the water with ozone. Currently Mote scientists are still in their testing phases, but there does seem to be a ray of hope on the horizon.