SCCF Marine Lab Director Eric Milbrandt, Ph.D., recently joined scientists from Florida Gulf Coast University for a second Florida Institute of Oceanography (FIO) research cruise to study the Gulf of Mexico after Hurricane Ian. Samples were collected to study carbon and nutrient cycling and phytoplankton communities in response to the hurricane. The research is intended to help understand how major hurricanes impact red tide blooms.

“We are investigating a pattern over the past 20 years in which long and intense red tide blooms can occur after a major hurricane,” said Milbrandt. “It happened after Hurricane Charley in 2004 and again after Hurricane Irma in 2017.”

FIO invited the scientists to conduct the research on board the R/V Hogarth based in St. Petersburg. The first cruise was weeks after the storm in mid-October when satellite imagery showed dark water from the tidal passes mixing with the Gulf of Mexico. 

The second research cruise was conducted in January 2023. Over a 5-day period, long-term monitoring sites established by SCCF in 2018 were visited in a grid pattern near Sanibel and Captiva. In addition, three transects offshore up to 80 miles were sampled along with other sites previously sampled by FGCU researchers. 

On the 7-day October cruise, scientists sampled about 50 offshore sites from St. Petersburg to Naples to investigate the potential development of a red tide bloom due to Hurricane Ian’s epic floodwaters. 

“Red tide blooms typically occur in Florida in the fall, and hurricanes are suspected to play a role in stimulating blooms,” said Milbrandt. “The heavy rainfall and flooding cause land-based nutrients to flow outward to coastal waters and blooms feed off those nutrients.”

Below is NASA satellite imagery showing dark water from the tidal passes mixing with the Gulf of Mexico shortly after Ian.