Thick, green algae mats Rubicon Canal in Cape Coral

Thick, green algae was present at the surface of the Rubicon Canal and smaller canals nearby in Cape Coral Thursday.

An expert says the algae is usually at the bottom of the canal but has floated to the top. It’s not harmful like blue-green algae, but it is unsightly.

This is the first time I’ve ever seen something like this here,” Ray Graulich said. “I was out here spraying it with the water hose trying to move all the algae away from the dock and to push it out, but somehow, it keeps coming right back in.”

“I’d like to see it gone,” Bill Hardin said.

Hardin told us, when he first saw the first patches earlier this week, we worried the algae could be harmful.

“Thats why we sent a picture to y’all,” Hardin said.

We took that picture and images we captured Thursday to professor Barry Rosen at FGCU’s The Water School. He put a sample of the algae under his microscope. He confirmed it’s green algae, but not toxic blue-green algae.

“These are all healthy, normal components of the ecosystem,” Rosen said. “They do not make any kind of toxin, but when they get thick, they produce big mats like this. You have a different kind of potential issue.”

Issues could include fish kills if the green mat sucks up too much oxygen down the line, and beware if it starts to smell.

“If it starts to take decay and break down, now, there could be some nasty gases that are released,” Rosen said. “A lot of people find the smell very offensive, and it’s not healthy to breathe in.”

We asked the City of Cape Coral if it plans to skim the algae from the canal. The city also checked with FGCU experts and were told the algae is normal and healthy for this time of year.

Note: One warning is the recommendation to keep pets away from the floating algae because it can be toxic if consumed.

Graulich hopes the green gunk disappears before any of that happens.

“I was hoping that the city would come here and maybe skim it, skim it all out,” Graulich said.