A viewer in Stuart recorded videos this week of manatees swimming through thick algae near North River Shores.
In just eight hours, one video by Chris Mascia Palas was shared more than 3,000 times.
Palas said she and her family spotted the manatee struggling in a canal behind their house.
“The water is like thick pea soup and has blue color in it as well. It stinks like a dead rotting something! .. (The manatee was) clearly was in search of fresh water as well as struggling to clear its airways,” wrote Palas.
Adam Palas wanted to help the manatee and said he gave it some clean water from a hose. "Every Time he came out he was just shooting out from his nose all the algae. You could just see him like blowing out green chunks out of his nose. It was really horrific."
The Florida Fish and Wildlife Conservation Commission said what Palas did was not illegal but the agency discourages the practice. FWC says it has not received any reports of manatees in distress.
Palas later posted another video of a manatee at North River Shores “struggling to clear its airways and his nose was clogged” with algae.
Biologists are expecting a fish kill to happen as a result of the algae blooms.