Plankton that turned Cocoa Beach canals 'tomato soup' red return with a vengeance

FLORIDA TODAY
Original Published 11:20 a.m. ET May 7, 2018 | Updated 5:02 p.m. ET May 7, 2018

COCOA BEACH — A mystery plankton that has residents here seeing red is keeping biologists guessing, for now.

A similar looking plankton turned a couple canals blood red late last month in this tourist town.

Then early Monday, a canal at 2nd Street South looked even redder.

When a few canals in the city first turned red around April 24, while water tests were pending, biologists had suspected a protozoan called Myrionecta rubra. Tiny hairs called cilia propel that wily critter through the water, so scientists said that mobility might explain the on-and-off redness in the water. 

Then water tests identified, among other things, the algae called Fibrocapsa japonica. But the samples were taken after the redness had vanished, so scientists weren't sure.

University of Florida tests of the late April algae bloom in Cocoa Beach canals showed Fibrocapsa japonica as predominant species causing the redness in the water, but also found other species of marine organisms that may be contributing to the discoloration as well. 

Now they suspect a third culprit: an algae called, Oxyrhis, which also propels through the water with a whip-like tail. 

"They move up and down the water column," said Ed Phlips, a biologist at the University of Florida who analyzes lagoon algae samples. "They may be moving down during the day. "Unless we capture it when it is at full color, then it makes it difficult to decide what the dominant (species) is."

The current bloom in Cocoa Beach canals is not “the” toxic red tide species of algae Karenia brevis, officials have said. Red tide produces brevetoxins, which can kill marine life and cause itchy throats and respiratory symptoms in humans.

The Oxyrhis algae is not toxic, or rare to the lagoon, Philips said. "We've seen it before," he said. Like other algae, the species can deplete oxygen dissolved in the water, causing fish and other marine life to die.

As of Monday afternoon, there were no reported dead fish associated with the this week's plankton bloom.

"It can cause low oxygen for sure," Philips said. "So you could end up for fish kill, for sure."