Green scum on Venetian Bay was not toxic blue-green algae, Florida Department of Environmental Protection says

The thick, green algae that covered portions of Venetian Bay earlier this month was not toxic blue-green algae but a mixture of several other species of algae, according to the Florida Department of Environmental Protection.

Collier County Pollution Control sampled the water last week after receiving a complaint from a longtime Naples resident who noticed a layer of green scum on the surface of Venetian Bay. 

The county sent the sample to FDEP, which tested the water for anatoxin-a and cylindrospermopsin, two toxins produced by a variety of freshwater cyanobacteria (blue-green algae).

"According to the FDEP analysis, no toxins were detected in the sample," said Danette Kinaszczuk, pollution control manager. "There was not a dominant (algae) species in the samples that was identifiable."

Last month FDEP detected blue-green algae in Moorings Bay in Naples. Stephanie Molloy, the city's natural resources director, said the algae originated in Swan Lake, which discharges into Moorings Bay.

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City staff has not seen any indication of blue-green algae in Moorings Bay, Swan Lake or Venetian Bay as of Tuesday, Molloy said, so the city has not requested further testing. The FDEP collects and tests samples only when an algal bloom is reported. 

"We will keep on monitoring the bay and communicate any reports of potential blue-green algae to Collier County Pollution Control and DEP," she said.

Molloy also said the city is actively taking steps to try to address water quality concerns, including implementing a revised fertilizer ordinance that prohibits the use of nitrogen-based fertilizers from June 1 to Sept. 30 when the nutrients are more likely to wash into the waterways. 

"The city has recently revised its fertilizer ordinance to help prevent nutrients from fertilizers, grass clippings and yard waste from entering our waterways," Molloy said.

"We are also encouraging all lakefront property owners to establish and maintain a 10-foot fertilizer-free, no-mow buffer zone of native plants at the lake edge, and littoral plantings nearshore."

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Linda Penniman, former city councilwoman and board member of the nonprofit organization Collier County Waterkeeper, said it's "good news" that the algae in Venetian Bay was not toxic, and she's optimistic about the city's new fertilizer regulations.

“Nitrogen and phosphorus are the two big contributors (to blue-green algae), so enforcing the fertilizer ordinance will certainly help," she said.

However, she still has grave concerns about blue-green algal blooms in other areas of the county and state.

Cyanobacteria are loaded with toxins, including BMAA, which noted ethnobotanist Paul Cox has linked to Alzheimer’s disease, ALS and other neurodegenerative diseases.

Penniman recently visited Cox's lab in Wyoming to learn more about the harmful effects of blue-green algae on human health and she also invited Cox to speak at an event in Naples in October.

FDEP spokeswoman Dee Ann Miller said the department is conducting "extensive sampling" on algal blooms throughout the state.

"To ensure the health and safety of our state's residents and visitors, the FDEP is committed to keeping Floridians updated on current algal blooms and how the state is responding to protect human health, water quality and the environment," Miller said.

To see FDEP's testing information, including sampling dates, locations and results, visit: https://floridadep.gov/dear/algal-bloom/content/algal-bloom-sampling-results.

Residents can also sign up to receive weekly updates via email.

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