Scientists are seeing concerning levels of algae this year in Florida's Indian River Lagoon just two years after massive blooms led to the worst fish kills on record.
Florida Today reports that biologists are measuring similar algae levels in the lagoon's waters that they saw before the devastating 2016 blooms.
The lagoon on the state's Atlantic Coast is one of the most biologically diverse waterways in the nation.
When algae grow at high concentrations in the water they remove oxygen used by fish, manatees and other creatures.
Kayakers are reporting that the lagoon's waters appear olive-brown in color, rather than clear as in years past.
While no fish kills have been reported yet, biologists are worried that the problem will worsen as temperatures rise.