Why is the water so green?
One empty boat trailer sat at the Highland Shores boat ramp in Ellenton on Friday morning.
While it was a blistering 90 degrees out with mostly clear skies and a slight breeze, the water was not inviting.
This week’s blue-green algae bloom weekly update from the Florida Department of Environmental Protection confirmed that the Manatee River is experiencing a large bloom of Aphanizomenon flos-aquae, a cynobacteria, or type of blue-green algae that typically blooms in fresh or brackish water.
“Manatee County indicated that blooms in these waters during the summer months are not uncommon,” DEP spokesperson Weesam Khoury said. “The growth of blue-green algae typically increases in the spring and summer months when water temperatures and daylight hours increase. Higher levels of nutrients in the water and sediment can lead to higher levels of cyanobacteria growth.”
Since last week, the DEP has taken more than a dozen water samples along the river, mostly between the DeSoto Bridge and Tidewater Preserve and Redfish Point.
The Florida Department of Health advises people avoid coming into contact with algae and recommends not swimming or fishing anywhere a bloom is present. More often than not, Aphanizomenon flos-aquae blooms are toxic. The toxins the algae is capable of producing, however, have not been detected in any of the recent samples taken in the Manatee River.
“Persistent blooms are routinely monitored and retested, and staff also regularly review satellite imagery and aerial photography, when available, to inform the development of daily sampling plans,” Khoury said.
The bloom that has turned the river shamrock green was visible from a distance on Friday at the Highland Shores boat ramp. A closer look revealed how the thick the algae was, making the water dark and with a slimy look to the surface.
Along the Bradenton Riverwalk near the skatepark, the water was visibly darker than usual on Friday and had a hue of green.
One sample taken off of Point Pleasant Avenue just east of the Twin Dolphin marina in downtown Bradenton tested positive for a mixture of algae species. The DEP visited Fort Hammer Park last week but no sample was taken because scientists did not observe an algae bloom in the water.
The bloom in the river, however, is not the same algae that has been clogging up and causing a stink at Robinson Preserve in northwest Bradenton. Testing there confirmed lyngbya-like algae in the water, a different species of filamentous cyanobacterium. Mats that lyngbya sometimes forms are what have clogged the preserve’s waterways.
Lyngbya-like algae has also been found in Sarasota and Palma Sola bays and near the inter-coastal side of Anna Maria Island since last month.
The Florida Department of Environmental Protection said those who see the algae blooms in the water can report the location so crews can test the water. Reporting algae blooms can be done on the FDEP website or by calling 855-305-3903.
To report a fish kill, call Florida Fish and Wildlife Conservation Commission at 800-636-0511.