A record 1,101 manatees died in Florida in 2021

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.