SARASOTA - Scientists believe Ocean currents, not fertilizers, are the major cause of 2018 red tide bloom.

A team of scientists from USF and FWC Research Institute  used an underwater drone to find the origin of last year's record red tide bloom. According to the Herald Tribune, the robotic glider was deployed for a month in the thick of the red tide outbreak to evaluate water that could have fueled ride tide. It picked up high concentrations of chlorophyll, a signature of red tide, near the bottom about 50 miles west of Tampa Bay.

The data was run through a computer model that found conditions ideal for underwater delivery of red tide cells to the coastline. During an upwelling, the Loop Current and its eddies can interact with the West Florida Continental Shelf in a way that causes upwelling strong enough to move nutrient–rich water from the deep ocean onto the shelf. This allows other algae to outgrow K. brevis.

In the middle of July a persistent upwelling began, but too late to suppress the bloom that was already moving toward the coast.