A state of emergency has been declared in Florida as invading blue-green algae chokes miles of its coastline – and the thick sludge spreading through the state's waterways is dangerous to both humans and wildlife.

Harmful algal blooms, caused when toxin-producing algae grow out control, do occur naturally, but human activities can also play a role. And the source of Florida's green slime, many reports say, lies miles away in its largest lake, the polluted Lake Okeechobee. 

Runoff from sewage, manure and fertiliser from farms has been fouling the lake for decades, and blooms of blue-green algae, also known as cyanobacteria, are a common sight there come summer. Warm water, sunshine and an abundant supply of nitrogen and phosphorous from the runoff allow cyanobacteria to thrive. By early May this year, a bloom covered 85 square kilometres (33 square miles) of the lake.

Okeechobee Nasa 2016 07 06
In early May, an algae bloom grew to cover 85 square kilometres (33 square miles) of Florida’s Lake Okeechobee. Image: NASA Earth Observatory

In recent weeks, officials have discharged large volumes of excess lake water into local canals towards the coasts, a tactic that's regularly employed when high water levels put pressure on Okeechobee's aging dike"Water managers started discharging water from the lake early this year to counter the large amount of winter rainfall. The river outflow carried nitrogen and phosphorous from the lake; it also freshened some downstream areas that are usually too salty for much algae growth," explains a post from NASA

Since then, harmful algal blooms have unfurled into canals, rivers and estuaries in four counties across southern Florida. Water samples have tested positive for high levels of toxins produced by the algae. Such outbreaks are not uncommon here, but the present situation, locals say, is the worst they've seen. Alarmed residents have been documenting the impact with photos and videos shared to social media.

One widely shared clip shows a manatee struggling to make its way through the foul-smelling sludge, which reports describe as "guacamole-thick". "It stinks like a dead rotting something!" says Martin County resident Chris Mascia Palas, who filmed the encounter. "This sweet manatee was way over across the canal and made its way to us. It must have drank at least eight gallons of water!"

At this point, it's not yet clear how Florida's threatened manatee populations will be affected by the algae, but conservation groups are monitoring the situation closely. Another animal, a dead juvenile, was recovered on Saturday, but tests are still needed to determine the cause of death. All of this comes just a few months after the US Fish and Wildlife Service proposed changing the manatee's endangered status to threatened.

"This is exactly one of the reasons why we strongly believe that downlisting the manatees at this point in time is premature," warns the Save the Manatee Club on Facebook. "Algae outbreaks like these occur and may get worse in the future." The group, which has been inundated with queries from concerned residents, has urged the public to report all sightings of distressed, sick or dead manatees to local wildlife officials. 

This past weekend, CNN meteorologist Jennifer Gray also shared video clips of algae-choked water, as well as footage of an alligator swimming through the slime. "If you think it looks gross, try smelling it! I can't believe this is Florida! Heartbreaking," she wrote on Instagram. 

Florida's water management officials have now reduced drainage from Lake Okeechobee in the hope of starving the algae. A hotline and website have also been set up for residents to report algal blooms. But many locals and conservation groups, who have been fighting for years to stop discharges from the lake, are blaming government inaction for what they see as an unfolding environmental crisis.

Polluted, fertiliser-laden water from lake, they say, has negative impacts beyond the toxic green sludge. Water quality, human health and fragile ecosystems off Florida's coasts, including seagrasses, oyster beds and fish populations, are all at risk. 

Environmental law firm Earthjustice says more must be done to control pollution, particularly in the form of runoff from agricultural operations. "Once again, pollution from sewage, manure and fertiliser is causing a nasty algae outbreak in south Florida. All this toxic algae is a result of Florida water managers' continued practice of releasing massive amounts of polluted agriculture waste per second into rivers that lead to the coast," the group says.

If you have come across wildlife affected by the blue-green algae, you can contact Florida Fish & Wildlife.


Top header image: Travis, Flickr