FGCU researchers study red tide found near Edison Reef off Sanibel

Published: December 1, 2020 3:54 PM EST
Updated: December 2, 2020 6:17 PM EST

An FGCU research team found red tide near Edison Reef off Sanibel’s coast recently.

A sample from researchers gathered from the Gulf showed a low density of the red tide organism, but it’s considered more than background levels. It’s the largest traces of red tide the FGCU team has seen in any sample it’s taken this season.

“It was definitely a mixture of excitement and worry,” said Alex Donnenfeld, an undergraduate researcher at FGCU. “Immediately, we knew something was definitely up. We saw a almost a sludge for about eight inches in the water column between 10 and 12 feet.”

Something else was fishy.

“That reef is usually teeming with life, so there was a slight decrease in the amount of fish we saw,” Donnenfeld said.

The team took a sample and brought it to a lab.

“So far, the samples have been nothing,” said Hannah Sims, an FGCU graduate student. “We’ve been looking at 15 mils of centrifuge tubes of nothing for months and months and months, and this is our first real sight of them.”

A refrigerator in the lab holds months and month’s worth of rust-colored water samples, but that’s not how it’s naturally found.

“What we use is an iodine-based solution, and so the iodine of course has that kind of brownish color,” explained Professor Mike Parsons, the FGCU Vester Field Station director. “And when we put it in, the water sample kind of gives it that rust color.”

Red tide typically starts to show up toward the end of fall. FGCU is going to look at satellite and ocean circulation data to try to understand why it’s showing up so late in the year.

“The question is are we seeing the beginning of a bloom, either in terms of the bloom moving inshore, or is it something that’s starting to grow now,” Parsons said. “And then that’s just what more research is going to let us know.”