Thick algae at Robinson Preserve makes tough kayaking
Kayakers found themselves facing unanticipated obstacles in Robinson Preserve on Monday with thick clumps of what appears to be blue-green algae clogging up waterways.
It’s leaving the kind of stench all too familiar to Manatee County residents and visitors who endured the prolonged outbreak of red tide last summer. Fortunately Karenia brevis — the organism responsible for red tide — is only being reported as a background presence off the coast of Sarasota County at this time, according to the Florida Fish and Wildlife Conservation Commission.
What is being detected in local waters in larger amounts — and potentially impacting Robinson Preserve — are the organisms associated with blue-green and brown algae.
“We’ve got it. It’s no longer a question,” said Manatee County Parks and Natural Resources Director Charlie Hunsicker.
What they don’t have, according to Hunsicker, is the laboratory necessary to test water contents, so county employees collected samples from Perico Bayou on Monday morning and drove them to the Florida Marine Research Institute in St. Petersburg for analyzing.
The results should come back within a few days.
Hunsicker said that the natural tidal flow through the Manatee River and Perico Bayou is usually enough to flush out low-oxygen waters caused by algae blooms.
“But now we are seeing such an overwhelming mass of dead and dying algae that even the tidal flushing is not enough to keep ahead of the oxygen-robbing effects that can cause fish kills,” Hunsicker said. He added that the combined, high presence of brown and blue-green algae in the lower Manatee River is creating a “one-two punch” effect on water quality.
As of the latest weekly reports from the FWC and the Florida Department of Environmental Protection, the preserve has not been tested. But where preserve waterways and the Manatee River meet was tested for filamentous algae, which are strings of algae that intertwine, forming a surface mat, similar to those seen in large patches within the preserve.
DEP also is reporting areas of the Manatee River between Ellenton and Bradenton that are testing positive for at least two separate organisms associated with blue-green algae and confirmed several blooms throughout the testing area.
Though Aphanizomenon flos-aquae and Cuspidothrix tend to contain toxins more often than not, DEP said in its weekly update that no toxins were found in the samples tested thus far, “but more results are pending.”
DEP tested 14 locations along the Manatee River, one spot in Palma Sola Bay and three areas along Anna Maria Island. Only the river testing has produced positive results.
Evelyn Gaiser, a Florida International University expert and a member of Gov. Ran DeSantis’ blue-green algae task force, told the Bradenton Herald that much like red tide, there is still much scientists need to learn about blue-green algae.
As to why organisms known to produce toxins don’t produce them sometimes, Gaiser said, “There is a lot to learn on that subject. We just don’t know.”
This is the time of year when naturally occurring blue-green algae blooms are the most common. Depending on the size of the bloom and toxicity levels, they can can produce illnesses similar to red tide.
Blue-green algae can thrive in fresh and brackish waters such as the Manatee River, but die upon contact with saltwater.
Gaiser said there is simply not enough information in DEP’s report to go on at this point, but she reiterated that blooms form naturally this time of year.
“Sampling continues. It’s Florida. It’s warm and if there’s nutrients in the water, it’s going to bloom and the size of the bloom will depend how much nutrients there are. Blue-green algae is good at taking metabolic byproducts, some of which are a bit nasty.”
DEP reports that heavier than average nutrient runoff can exacerbate the situation, and experts predict that will be the case this year.
Aphanizomenon flos-aquae, in particular, tends to show up in areas that are heavily loaded with nutrients, according to the DEP.
Experts knew this summer’s runoff into the Gulf of Mexico would be nutrient and pollutant heavy. The National Oceanic Atmospheric Administration just weeks ago predicted a near-record “dead zone” for the Gulf given all of the flooding across the Midwest this spring.
Cindy Heil, director of Mote Marine Laboratory’s Red Tide Institute, told the Bradenton Herald June 12 that signs of heavily deposited nutrient areas were already being seen off the coast of Sarasota. Heil does not believe it will play a factor in another red tide outbreak.
Gaiser doesn’t, either, and despite some varying opinions on how blue-green algae affect red tide, she sides with those who believe there isn’t enough evidence to link the two.
They have some things in common, “But I’ve not seen anything convincing that links the two except for the potential overlap in causes,” she said. “There’s still a lot of work to do in what’s causing it outside of the natural thing.”
DEP also is reporting that the blue-green algae in Lake Okeechobee could intensify, noting that 15 percent of the lake “indicates medium to high blue-green algae potential,” but satellite imagery shows no signs of the algae in the lake’s estuaries at this time.
“Some — not all — blue-green algae can produce toxins that can contribute to environmental problems and affect public health,” DEP reports. “Little is known about exactly what environmental conditions trigger toxin production.”
In Manatee County, Hunsicker says that they will let nature run its course unless the fish kills caused by the algae become more lethal.
“Letting it go too far can create a downward spiral that sometimes needs intervention,” Hunsicker said. “But we let the natural environment address what it can before getting involved.”
Hunsicker said that the county is also working on efforts to prevent potential human effects on bloom intensity, including better stormwater management and street sweeping procedures.