FORT MYERS BEACH, Fla. — Fox 4 Meteorologist Andrew Shipley responded to Fort Myers Beach after receiving calls about distressed birds. Upon arrival at Estero Island, he immediately noticed a strong rotten egg smell in the area.
"As soon as there were two, I was starting to look around for something out of the ordinary. And then bird after bird after bird," said Rob Howell, naturalist at the Pink Shell resort.
Howell had a busy Friday morning, finding six sandwich terns in distress, including one discovered while Shipley was on the island investigating the reports.
"Some of the birds I was able to walk up and pick up. This one guy is a little livelier, which is a good sign. Which means he will probably make it to the hospital in time," Howell said.
Each affected tern was carefully boxed for transport to CROW Animal Clinic for treatment. Howell reported that others had seen similar incidents along the beach.
"Some of the other turtle patrols said that they had seen dead ones going up the beach on their walks as well," Howell said.
Initial red tide concerns ruled out
The combination of the rotten egg smell and tannic waters initially raised concerns about red tide, but Howell observed different symptoms in the affected birds.
"With red tide they almost act like they are drunk. So, I don't think it is red tide. These guys are almost acting sleepy and every now and then their heads are shaking a lot," Howell said.
To determine the cause, Shipley collected Gulf water samples and took them to Florida Gulf Coast University's Vester Field Station for analysis. The testing confirmed Howell's suspicions that red tide was not the culprit.
Massive algae bloom discovered
Laboratory analysis revealed the presence of protoperidinium quinquecorne, a different type of dinoflagellate algae than the organism that causes red tide.
"It's called protoperidinium quinquecorne. It's not a toxic producer like red tide is. Red tide is another dinoflagellate. But the sheer volume of this could produce noxious chemicals," said Dr. Mike Parsons, a professor of marine science at FGCU's Water School.
The scale of the bloom was significant, according to Parsons' preliminary calculations.
"This is a lot. Just doing some quick math. If I am anywhere close on my numbers, we are probably looking at 10s of millions of cells per liter of water. That's a bloom for sure, and that is a pretty big bloom," Parsons said.
Possible hydrogen sulfide exposure
While the connection between the algae bloom and the sick birds requires further investigation, Parsons offered a potential explanation for the wildlife impacts.
"My first thoughts are that maybe the birds were exposed to hydrogen sulfide. Hydrogen sulfide has that rotten egg smell and it can be a toxic gas," Parsons said.
An official determination about what caused the birds' illness will need to come from CROW Animal Clinic staff after they examine the affected terns.
Recent rains may have contributed
Parsons suggested that recent heavy rainfall last weekend may have contributed to the bloom's development.
"This species tends to live in estuaries. So, that is where your river water meets the ocean water, and it mixes. So, they can tap into those nutrients that could be coming in from runoff," Parsons said.
Bloom expected to persist
As the Labor Day holiday weekend is upon us, Parsons warned that the algae bloom may continue for some time.
The cells are healthy and as long as nutrients remain available and ocean currents allow, the bloom will likely persist in the area.
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