A dead Snook is shown along the water's edge in Bradenton Beach, Florida.
Florida's Governor this week made official what residents of southwest Florida already knew: the bloom of toxic algae that has darkened gulf waters is an emergency.
The red tide has made breathing difficult for locals, scared away tourists, and strewn popular beaches with the stinking carcasses of fish, eels, porpoises, turtles, manatees and one 8m whale shark.
Governor Rick Scott declared a state of emergency in seven counties stretching from Tampa Bay south to the fringe of the Everglades. Scott promised US$1.5 million ($2.8m) in emergency funding.
Residents in crowded retirement communities are reporting respiratory distress from the vapours of the microscopic red-tide organism called Karenia brevis.
A recent study found a 50 per cent spike in hospital visits resulting from respiratory problems during red-tide blooms.
Florida’s governor issued a state of emergency because of algal blooms called "red tide." The toxic algae — whose growth is boosted by climate change and fertilizer runoff — has killed thousands of animals including fish, dolphins and endangered turtles. pic.twitter.com/sj33nceqZq
The red tide has been gradually moving north, to the mouth of Tampa Bay, according to state data tracking the red tide. For many places, the daily reports continue to say "Water Color: Dark" and "Respiratory Irritation: Intense." Worst of all are the reports that state, "Dead Fish: Heavy."
Rick Bartleson, a research scientist with the Sanibel-Captiva Conservation Foundation, said water samples offshore show lethally high concentrations of algae.
"There's no fish left. Red tide killed them all," he said.
The algae is found in marine environments for most of the year, but the past two months have produced high concentrations, said Kelly Richmond, a spokeswoman for the Florida Fish and Wildlife Conservation Commission. The duration of blooms can be affected by sunlight, nutrient and salinity content, she said.
Scientists are trying to figure out why, exactly, the current red tide along the Gulf Coast has been so protracted and deadly.
State officials and scientists point out that, at base, this is a natural phenomenon. Fish die-offs were noted by Spanish explorers in the 1500s and have been well documented since the 1840s.
But the incidences of red tides seem to have increased since the 1950s and 1960s. Climate change could be a factor - warmer waters, up to a certain point, are congenial to algal growth. The Gulf of Mexico's surface temperature has warmed by about 1.1C since 1977.
There is a more direct human handprint on the current crisis: Florida's landscape and the flow of water have been radically altered by agriculture, canals, ditches, dikes, levees and the sprawling housing developments that have sprouted as the state's population has boomed.
Some scientists hesitate to declare a direct cause and effect, although Bartleson said of the current red tide, "It's on steroids with our nutrients."