Study finds horse-associated bacterial DNA in Palma Sola Bay samples; no human sewage detected

The Sarasota Bay Estuary Program presented a source‑identification study Sept. 10 showing detectable—but unquantified—genetic signatures linked to horses at three of four sampling sites in Palma Sola Bay, while tests returned no detectable human (sewage) signal.

Dave Temasco, director of the Sarasota Bay Estuary Program, told the Bradenton City Council the team used DNA‑based methods that can apportion indicator bacteria to likely sources such as humans, birds and horses. Temasco said the lab results available from the first sampling event showed horse‑associated DNA at three sites and a bird signal at the bathing beach site. When a source was detected, Temasco said, the abundance of that source in the total bacterial mix was too low to quantify.

The study followed public concern about elevated enterococci counts on the north side of the Palma Sola Causeway, where chartered horseback rides and some private horses enter the bay. Temasco said the region’s overall water‑quality indicators have improved in recent years: nitrogen concentrations and chlorophyll have trended down, and seagrass coverage has increased…