Scientists monitoring 'big blob' in Gulf waters off Sanibel

A large patch of discolored water is blanketing the south coast of Sanibel Island, and water quality scientists are monitoring the water to see what is causing the big blob.

Some have guessed it could be an algal bloom, while others say it's a group of diatoms or just a giant balloon of extra salty water.

"It does look like a bloom, but a bloom of what," said Rick Bartleson, a water quality scientist with the Sanibel-Captiva Conservation Foundation. "It just has the right look of a bloom except it doesn't have the right color for trichodesmium."

Trichodesmium is found in tropical waters around the world and blooms when natural nutrients conditions become out of balance.

Algae blooms can cause fish and marine mammal kills, discolor the water and cause the closure of swimming beaches.

Pictures taken by the Calusa Waterkeeper show a large patch of whitish, milky-green waters surrounding the south end of Sanibel Island.

The group first noticed the blob Sunday.

"Our perception is the spatial scope was a little bit bigger today (Monday)," said John Cassani, with Calusa Waterkeeper. "There are some areas that are extremely thick. It looks like someone spilled fluorescent green paint and that the current has spread it all around."

Cassani said he reported the water conditions to the Florida Department of Environmental Protection.

Bartleson and others at SCCF expect to take more water quality samples this week.

"It could be an accumulation type bloom when things wash this way in the Gulf and those currents can concentrate any kind of phytoplankton out there," Bartleson said. "It looks like a bloom of something."

Connect with this reporter: Chad Gillis on Twitter.