With red tide, the water might be a little discolored with a hint of red or brown but it's not always visible.
Florida's southwest coast, a ribbon of inlets and barrier islands normally brimming with wildlife, has become a red tide slaughterhouse this summer. The state's governor has declared a state of emergency.
"As we continue to work with our partners to respond to the ongoing red tide event in Southwest Florida, we ask that you report any dead or distressed marine mammals and see turtles to our wildlife alert hotline", the FWC wrote on its official Instagram account Wednesday alongside images of workers rescuing a manatee sickened by red tide exposure.
Dozens of sea turtles are also turning up dead.
"FWC will deploy additional scientists to assist local efforts to save animals affected by the naturally occurring red tide". The algae bloom - which gets its name because the microscopic algae often turn water red - has already lasted since November of previous year, and could stretch into 2019, some scientists are saying.
Most algae blooms are beneficial to the ocean, providing a source of food for marine creatures.
For people with severe or chronic respiratory conditions, such as emphysema or asthma, red tide can cause serious illness.
Toxic freshwater algae blooms started inland at Lake Okeechobee.
The harmful effects are caused by toxins that are released when the organism dies, so killing the algae would produce even more toxins in the water.