The return of the blue-green slime
This summer could prove the worst ever for harmful algae blooms in Lake Erie
He smelled it before he saw it.
It reeked of rotting fish, or an open sewer. It was strong. Nauseating.
Then Jeff Vidler came face to face with “this slimy, thick green stuff floating on water. It had even washed up on the shore.”
He knew what it was: toxic blue-green algae. It was spread as far as he could see at a beach near Port Glasgow, a tiny community about 75 kilometres southwest of London, Ont. The stuff was bobbing up and down in little waves, in different shades of green.
Vidler, a harbourmaster at Erieau, an- other small Lake Erie cottage community close to Port Glasgow, had seen small quantities of it before, but never a “sea of algae,” which he calls “scary.”
That was the summer of 2011, the year blue-green algae invaded Lake Erie with the largest bloom ever recorded, covering as much as one-sixth of the surface.
The bloom extended from Toledo, Ohio to beyond Cleveland and along the Ontario shore. It extended more than 20 kilometres from the shores, and in the central basin it was observed at a depth of at least 18 metres.
It’s a memory that cottagers, beachgoers, boaters and businesses related to tourism would like to forget.
But that may be difficult in 2013. For the algae could be as bad, or worse, this summer.
Weather forecasters point to a wet spring.
That prediction is worrying for scientists because the rainier the weather, the worse the outbreak of algae.
Swathes of blue-green algae are caused largely by phosphorus runoffs, researchers say. Phosphorus is used as fertilizer. It’s also in manure and other waste products from agri-business operations such as pig farms and greenhouses. Algae thrive on phosphorus. “When it rains a lot, we see more phosphorus runoffs,” says Raj Bejankiwar, the lead scientist of the International Joint Commission’s Lake Erie Ecosystem Priority (LEEP). “This year, if the weather forecast is accurate, there is possibility of high phosphorus runoffs.”
He doesn’t know how bad it could be, but gently reminds that “2011 saw a wet spring and the lake was invaded by algae blooms. “It was pretty bad.” The algae caused the closure of dozens of beaches in Canada and the U.S., making a considerable dent into tourism. Its density also slowed down boats.
As long as algae are alive, they float on the surface. When they die, they sink to the bottom of the lake, where they decay and suck oxygen out of the water, killing fish. Hundreds of thousands of dead fish washed up on Erie’s shores in September 2011, triggering panic among those who lived by the lake.
Not all types of algae, a simple aquatic organism, are destructive. In fact, some are beneficial to other aquatic life. But blue-green algae can contain E. coli bacteria, which is harmful when ingested by humans or pets. It may also contain cyanotoxin, which can cause skin irritation, respiratory difficulty and gastrointestinal distress in humans.
Blue-green algae also thrives on light. Lake Erie is the shallowest of the Great Lakes, especially at its west end, and thus more susceptible to algae than its deeper cousins.
Algae blooms are not a new problem in Lake Erie. In the 1960s, parts of the lake were declared biologically dead because of algae invasion. People on both sides of the border gave up on it.
Then, in 1972, Canada and U.S. signed the Great Lakes Water Quality Agreement, leading to a multibillion-dollar investment to reduce the phosphorus flowing into the lakes. Governments worked hard to get rid of phosphorus in detergents, improved sewage treatment plants and drastically changed farming practices.
The two countries called for an annual cut of more than 12,000 tonnes in phosphorus use. At the urging of officials and conservation agencies, hundreds of Lake Eriearea farmers changed their practices to reduce the amount of the chemical that washed away with dirt from their fields.
Lake Erie recovered. But in 2000, blue-green algae reappeared. And 2011 was the worst year ever. CLIMATE CHANGE, say scientists, is the new culprit in the algae conundrum.
Lake Erie’s waters are warmer, and rain showers are more intense, causing more phosophorus runoff, says John Nevin, who works with the International Joint Commission’s Lake Erie Ecosystem Priority. “It makes for perfect conditions to cause algae droves.”
The lake got a break in 2012; it was comparatively dry, and so there were fewer algae blooms.
Deforestation, mainly because of real estate development in recent years, has also played a role in the return of the slimy green sheet, re- searchers say. Fewer trees on the banks of streams means more phosphorus gets into waterways and eventually into lakes.
But where is all this phosphorus coming from?
That is one of the main questions LEEP is trying to answer, Nevin says. “There are some theories but the key element is to figure out why and what to do,” he says. He notes that there appears to be a new form of phosphorus draining into the lake, one algae feed on more readily. Can Lake Erie be cleaned again? In February, under the auspices of the International Joint Commission, scientists from Canada and the U.S. met in Windsor to focus on the sources of algae, the impact of climate change and solutions to the problem.
Experts say there is no one solution, but an obvious thing to do is to cut phosphorus levels once again.
LEEP’S Bejankiwar says there’s a certain urgency to cutting it back. “Algae are already causing an economic impact,” he notes. It is difficult to put a dollar value on it because the lake straddles a big area in two countries, but “there is evidence that it is impacting fishing, recreational use of water, tourism and even drinking water.”
Farmers and others who live on the shores of the Great Lakes need to be educated about the impact of algae blooms, says Geoff Peach, the coastal resources manager for the Lake Huron Centre for Coastal Conservation in Goderich, Ont.
Algae blooms are not as big a problem in Lake Huron, but in the past decade they have shown up, and according to some observers, they have grown larger every summer.
It’s impossible to predict whether 2013 will be a bad year for Lake Huron, Peach says, “but if there is enough phosphorus and heavy rains, and if water temperature goes up, we expect it could be.”