MELBOURNE, Fla. (AP) — What ignited the "superbloom" and brown algae that killed 60 percent of Indian River Lagoon seagrass?
And what snuffed out 135 manatees, 300 pelicans, 76 dolphins and a half-billion dollars worth of seagrass?
If William of Ockham were trying to answer that, he might have started with the extreme cold, dry weather of 2010 and 2011. His 14th century philosophical precept, Occam's Razor, holds that the simplest among competing theories is usually the best starting point. First, flesh out theories requiring the fewest assumptions, before moving on to more complex, refined explanations.
That hasn't stopped an army of armchair ecologists. They're filling a void left by biologists confounded by the complex unraveling of the lagoon ecosystem, which began swirling in a death spiral in 2011. Few answers have surfaced as to what catalyzed so many casualties, including a combine
73 square miles of seagrass, the estuary's primary nursery for life.
So semi-baked theories abound.
They range from the mundane — cold snaps — to the strange — Doppler radars slowly "baking" the biology with microwave radiation. That one's new. A theory blaming manatee overpopulation has been around for years.
Biologists working the problem agree on the 2011 "superbloom" as the seminal event. It nearly wiped out the lagoon's seagrass.
Just two years earlier, seagrass was thriving at levels not seen since the 1940s. Restoration efforts finally seemed to be paying off and the recent drought meant less polluting runoff into the waterway.
Then in early spring of 2011, a green monster "superbloom" of phytoplankton cast a dark cloud over that success. It eventually stretched from southern Mosquito Lagoon to just north of Fort Pierce Inlet, blocking sunlight from seagrass and leaving death in its path.
After rounding up all the bodies, scientists continue to sift through countless, nebulous clues, most just leading to more questions, hypotheses and dead ends.
Scientists working the problem say they're open to new ideas, however seemingly bizarre. But first they must round up all the usual suspects, before heading down more rabbit holes, into more extreme, data-deficient pondering.
Everything's on the table: Viruses. Bacteria. Toxins. Red tides. Brown tides. Green tides. Lack of tides. Or maybe nature just biting back from man-made problems forged over decades finally reaching a tipping point. Doppler radar, dark matter and manatee fecal matter will have to wait in line, biologists say, while other simpler theories are exhausted first.
Here are just a few of the theories waiting in the wings:
Fertilizer is the main culprit feeding toxic algae blooms: Runoff carries nitrogen and phosphorous — the active ingredients in most fertilizer — into the lagoon to spur excess algae.
Grass clippings, especially, can carry the two nutrients into the lagoon. So many local governments, including Brevard County, have in the past year adopted June 1 to Sept. 30 bans on fertilizer use and other measures stricter than state recommendations.
Advocates for the stricter rules point to studies that show lawns survive just fine without fertilizing during rainy months.
Fertilizer counterpoint: Rainy-season bans and other stricter rules don't follow the best available science and can have unintended consequences. Fertilizer and lawn-care interests point to an 8-year, $4.2 million state-funded study by the University of Florida. It found that depriving lawns of nutrients when grass is most able to absorb them — during peak growing season — can result in more nitrogen and phosphorus running off the weaker grass when applied at other times of the year.
Drift algae doomed the lagoon and its seacows: Drift algae has been choking out seagrass for years. And some scientists think the reddish-brown, stringy stuff may be linked with the manatee deaths.
In healthy amounts, drift algae provides food and cover for marine life and sponges up harmful nutrients from the water. But in excess, it clogs out seagrass.
Drift algae has entangled the lagoon in a boom-and-bust cycle in recent years, leaving the estuary with too much or too little.
In 2010, Nova Southeastern University found drift algae had increased by 46 percent in two years, to 102,162 metric tons over the 109 square-mile study area. But after severe cold spells, drift algae crashed in mid-2010, releasing a huge pulse of nutrients that may have spurred the 2011 superbloom.
Biologists speculate that without enough seagrass to eat, manatees shifted to mostly drift algae.
Many of the manatees that died mysteriously had the stuff in their guts. That diet shift could have altered the mix of good and bad bacteria in the animals' digestive tracts, leading to immune suppression, state biologists say.
An FAU-Harbor Branch researcher suspects toxins from a microscopic algae clinging to the drift algae.
Drift algae he collected in Cocoa Beach last year turned up toxins that killed mammalian cells in a lab.
Drift algae counterpoint: Scientists have yet to identify a specific toxin behind the manatee deaths. Also, there were no reports of twitching, rolling and other odd manatee behaviors usually associated with toxins.
Just because the algae toxins killed cells in a lab doesn't mean that's specifically what killed the manatees, state biologists say.
"There's a long way between that and actually demonstrating that it could actually kill a manatee in the Indian River Lagoon," said Jan Landsberg, who's heading up the lagoon investigation for the state's Fish and Wildlife Research Institute.
Biologists also aren't sure whether the drift algae die-off in mid-2010 was the major internal source of nutrients fueling the 2011 superbloom or just one of many.
Muck theory 1: A half-century buildup of muck that resembles "black mayonnaise" coats the lagoon bottom and that of its tributaries, in some spots more than 10 feet thick. It's mostly soil runoff from sod, construction sites, farming and erosion along lagoon tributaries, but also rotting algae and dead plants. Muck limits seagrass growth and the fish and organisms that need seagrass to survive. It contributes to bacterial decay, which consumes oxygen, causing fish kills. Muck also produces noxious chemical compounds, such as the hydrogen sulfide that creates the lagoon's occasional rotten-egg smell.
Some scientists say contaminants in the muck deposits may be contributing to the cancers and other wildlife health problems.
Lagoon sea turtles and dolphins are riddled with fungal growths and tumors. And biologists are finding higher incidence in Brevard than elsewhere in Florida of a strange cancer in redfin needlefish, especially in the Banana River. Needlefish are an important bait fish.
Scientists say dredging out muck could vastly improve the lagoon, and better land-use practices are needed to prevent more muck from entering the estuary.
A state sentate committee has recommended $20 million in state funding to dredge muck from the northern lagoon, ranging from about Titusville to Sebastian, with the Eau Gallie River topping the list.
A coalition of five counties, including Brevard, wants $100 million for muck dredging and other lagoon water quality improvement projects.
Brevard County Commission is asking the state for $887,000 to study and reduce muck. If funded, the project would remove weeds that rot to form muck in ponds, which ultimately empty into the lagoon. It also would pay to map how thick and toxic the muck is in specific locations.
Counterpoint: Dredging muck is expensive, takes years to permit and is not a panacea. Where do you put the muck? How do you keep more from entering the lagoon?
Muck theory 2: A government restoration project unleashed more muck that triggered the superbloom.
In June, a Volusia County clammer lost a legal attempt to stop the St. Johns River Water Management District from restoring 600 acres of coastal marshes in the Mosquito Lagoon. Mike Sullivan, who continues to challenge the project, says the district failed to maintain barriers to prevent muck sediment from old mosquito impoundments from entering the lagoon when they filled old ditches in 2009, clouding out his clams and other wildlife near Cedar Creek Island.
Counterpoint:District officials say the superbloom began in the Banana River area, then spread to the Indian River Lagoon and Mosquito Lagoon. The district has been reconnecting mosquito impoundments and filling in drag-line ditches for two decades, without similar ill effects.
State tests found no spikes in cloudiness or other water quality issues near the restoration project. Marsh restorations ultimately improve water quality and habitat.
Doppler radars caused the collapse: Stewart Simonson, a chemical engineer in Atlanta, spells out his theory on his blog called, Dark Matters a Lot.
Simonson believes that Doppler radar, by monitoring the weather, actually changes it, and puts the lagoon on a "slow microwave bake" of sorts.
He finds many fish kills, algae blooms and wildlife die-offs in Florida and elsewhere happen within about 25 miles of radar sites, and especially where radars overlap.
About 10 high-powered military, weather and aviation radars within a 25-mile area of Cape Canaveral pump microwave energy into the atmosphere, Simonson says, resulting in ionized plasma bouncing back as weather disturbances, waterspouts, lightning and sinkholes. It also ionizes the water, triggering algae blooms, fish kills and other wildlife die-offs and diseases.
"It's more like Pandora's Box, rather than outside-of-the-box," Simonson said of his theory.
"You've got about 11 million watts of pulsed radar power going into the atmosphere in that area, and a lot of it's reflecting back. That's how Doppler works. It reflects it back and it scatters."
Pollution and chemicals in the weakly ionized microwave "bath" become much more reactive, he says.
"It's like the energy that stirs up the soup," he said.
"You're on a really low cook," Simonson added. "The statistics show it's significant ... It's speeding up the ionization and decay in the water," he added. "Biologically, things are simmering."
Counterpoint:Lagoon investigators say this one's barely a blip on their radar, but that anything's possible. Although, it would take a much more thorough examination to establish the Doppler link.
Most of the radars have been here for years.
"It's not like we've added that much in the way of new Doppler radar stations," said Chuck Jacoby, the environmental scientist with the St. Johns River Water Management District who's leading the "superbloom" investigation.
"I don't think anybody's nailed down those connections yet," he said of the theory.
Too many manatees caused the crash: Local boating-rights advocates who opposed slow-speed manatee zones have long supported this theory. It goes as follows: Too many manatees — lured here by warm-water power plant discharges — gobble up seagrass by the roots. Their excretions add excess free nitrogen for seagrass-choking phytoplankton to feed on.
The two power plants in Port St. Johns pump in lagoon water to cool equipment at the plant, discharging warm water near the plants. That has conditioned manatees to stay farther north longer than they otherwise would, stressing seagrass beds beyond their ability to recover.
Counts have spotted more than 1,700 manatees in Brevard.
Bob Atkins, president of Citizens for Florida's Waterways, recently spelled out the theory in the boating-advocacy group's newsletter.
"We know that manatees consume, on average, somewhere between 40 and 150 lbs. of seagrass each day," Atkins wrote. "We also know that left unmolested, a healthy acre of seagrass can produce up to 10 tons of seagrass each year. So running the numbers, each manatee consumes somewhere on the order of 7 to 27 tons of seagrass in a single year."
Advocates of this theory say the power plants should install cooling towers to eliminate the "thermal pollution," so manatees will resume their historical migration pattern.
Counterpoint: State biologists say there aren't enough manatees to make a significant difference and that seacows mostly recycle existing nutrients in the system, rather than adding new nutrients. The 545,000 people in Brevard County eclipse the few thousand manatees swimming around at any given time. Humans have added new nutrients to the system from fertilizer and human waste. "To some extent, manatees, they're not importing nutrients from very far away," said Chuck Jacoby, the scientist leading the "superbloom" investigation for the St. Johns River Water Management District. "In my mind, it's more like a recycling than it is an introduction."
Cooling towers would be costly, and training manatees to migrate would be difficult.
A "perfect storm" of extremes aligned. Drought, then cold, set the stage for death.
Cold snaps in 2009, 2010 and 2011 killed fish, manatees and stunned sea turtles.
Lagoon water temperatures dipped as low as 39 degrees Fahrenheit in January 2010. Then red drift algae, the stringy stuff that looks like seaweed, crashed in mid-2010, rotting and increasing nutrient availability for phytoplankton growth. Also, less drift algae was around to sponge up nutrients in the water.
Decomposing fish and other marine life that died in the cold also left behind more nutrients for algae to thrive.
Drought made the lagoon saltier than usual, favoring the harmful algae species that bloomed and choked out seagrass.
Other possible factors include wildfires in 2011 contributing to the nutrient fallout.
"The system just didn't have the sort of capacity to cope with some of the other events that happened," said Chuck Jacoby, the scientist leading the "superbloom" investigation for the St. Johns River Water Management District.
Counterpoint: The lagoon withstood additional nutrient influx and cold snaps for decades, without showing major signs of stress.
Septic tanks and leaky sewer pipes are leaching nutrients into the lagoon: An estimated 300,000 septic tanks along the lagoon, including 90,000 in Brevard, sit in sandy soils that in most cases are poorly suited for removing contaminants from wastewater.
Brian LaPointe, a research professor at FAU-Harbor Branch Oceanographic Institute in Fort Pierce, says septic tanks remove 60 percent of the nitrogen in wastewater, leaving an estimated 2.2 million pounds of nitrogen per year entering the northern lagoon region.
Septic tank waste in groundwater can flow at rates of 3 to 6 six feet or faster per day, he says.
Lagoon-wide, he finds evidence of human waste in the forms of nitrogen locked inside the drift algae itself. That waste feeds toxic algae overgrowth. LaPointe suspects a toxic microalgae clinging to the lagoon's seaweed is causing the manatee deaths.
Dolphins could be at risk, too. A 2011 paper by FAU-Harbor Branch, Georgia Aquarium and NOAA cited septic tanks as contributing to the presence of E. coli bacteria in the lagoon's bottlenose dolphins, especially those captured near high densities of septic tanks, within a few days of heavy rain.
Studies funded by the St. Johns River Water Management District show septic tanks do a fairly good job treating human waste, as long as they're properly maintained. But Florida counties with inspection programs find 8 to 11 percent of the septic tanks are failing.
Assuming a 10 percent failure rate, that could mean 9,000 failing septic tanks in Brevard.
Sewer systems aren't always better, especially older ones with chronic leaks and spills.
In March 2011, a broken gear in a sewage-treatment tank led to the biggest sewage spill in Cocoa Beach history. The city had to pump 10 million gallons of partially treated sewage into ponds on the adjacent city-owned golf course off Minutemen Causeway between March 13 and 17 of that year. A ditch links the series of ponds directly to the Banana River.
Counterpoint: Florida Tech scientist Tom Belanger says septic tanks' overall contribution of nutrients is minimal, because the vast majority of tanks function properly. He finds plumes of septic tank nutrients travel slowly: 1-3 feet a year.
Belanger says excess nitrogen in the lagoon may be coming more from wildlife, such as manatees and raccoons. There are an estimated 12,000 feral pigs on the Merritt Island National Wildlife Refuge, for example.
The Cocoa Beach spill is not thought to be enough volume to trigger the superbloom. At the time, the city acknowledged some sewage had reached the Banana River, but how much is uncertain. The spill left behind no immediate ecological smoking gun, such as a directly-resulting algae explosion in the Banana River.
Information from: The (Fort Myers, Fla.) News-Press, http://www.news-press.com