The sparkling white sand of Florida's southwestern beaches aren't dotted with sunbathers this week.
At least 400 sea turtles have died, Newsweek is reporting.
The Florida Fish and Wildlife Conservation Commission is now examining samples of the algae from different locations along the west coast.
The state wildlife agency says red tide, a type of algae, has been a naturally occuring phenomenon along Florida's Gulf Coast since at least the 1840s and that blooms occur almost every year in the Gulf of Mexico. Tissue taken from the whale shark's organs and muscles tested positive for brevetoxin, a neurotoxin created by the algae.
Tourists weren't scattered on beaches in southwest Florida on Thursday, but hundreds of dead fish were.
Blue-green algae blooms have been plaguing the area for months, choking the waterways and bring foul smells and dead wildlife along the Caloosahatchee River.
Sea turtles, manatees, fish and other animals are seeing a spike in their mortality rate during 2018, especially in Southwest Florida. The FWC reports that this recent bloom has been monitored since November. The toxin affects marine life and causes respiratory irritation in humans and animals.
FWC officials also want to quickly remove the bodies of dead marine life because their decomposition only works to fuel an already relentless red tide bloom.
"It's hard to predict more than a few days out [when it will end]", Florida Fish and Wildlife Conservation Commission spokeswoman Michelle Kerr told CNN.
Usually, cold spells break up or kill off some of the algae, but not this time. Those who are looking for spots free of red tide can visit https://visitbeaches.org and myfwc.com/redtidestatus to see which beaches have been affected.