Florida recorded an astonishing 1,101 manatee deaths last year, according to the state's final preliminary 2021 mortality report published Wednesday.
The number smashes the previous record of 830 set in 2013.
Between the lines: Even though the first dead manatee of 2021 was found in Tampa Bay, officials believe the record is due mostly to depleted seagrass beds around a main manatee winter feeding ground at the Indian River Lagoon.
The number of reported deaths in December was far higher than November despite a supplemental feeding program, which could forecast another rough winter ahead.
What's new: For more than a decade, fertilizer leaching and stormwater runoff were thought to be the major drivers of the harmful algal blooms that kill seagrass, but new research shows that septic systems deserve more blame.
Researchers studied the effects from more than 300,000 septic systems in six counties along the 156-mile Indian River Lagoon and found that even properly functioning septic systems contribute algae-causing nitrogen to shallow groundwater.