Another invasive species is keeping Lake Simcoe scientists busy this summer.
To the untrained eye, the foreigners are being mistaken as plain old zebra mussels.
But it’s a species called quagga mussels that scientists and anglers are keeping an eye on.
“They look almost exactly like zebra mussels, but they’re a separate species. They are like zebra mussels 2.0,” Lake Simcoe Region Conservation Authority limnologist Brian Ginn said.
Zebra mussels were first found in Lake Simcoe in 1991, feeding on algae and particles in the water column.
Typically, their invasion is cyclical, eating until food is scarce, then they start to die off.
Quagga mussels also come from the Caspian-Black Sea area in Europe and were first noticed in Lake Simcoe in 2004.
“Quagga mussels can survive on less food than zebra mussels and they can close up and survive periods without food,” Ginn said. “They are also better in cold water.”
Zebra mussels would spring to life once Lake Simcoe reached 12 to 20 degrees, he said.
Quagga mussels are active at 4 C, which in Lake Simcoe is year-round, Ginn said. They also don’t mind a sandy bottom and are found across the lake.
As a result, Ginn has seen changes in the water.
“We used to have this big algae bloom in the spring that would set up the food chain for the entire year,” he said. “Now, the quagga mussels are eating the spring algae bloom.”
However, scientists are also learning the food chain is adapting.
“With the zebra mussels, they actually created more food for bugs in the lake.”
Bugs like shad flies and midges live on mussel debris.
“There were more bugs where zebra mussels were found, and little fish like to eat bugs and big fish eat the little fish,” he said. “In the shallow water, it actually increased the amount of fish.”
Lake Simcoe fishermen are noticing lake trout and whitefish are starting to eat the quagga mussels.
“They are an alternate food source for some of the whitefish and the perch. Gobies also eat them when they are small. You get a lot of fish with red lips,” angler and Lake Simcoe Message Board administrator John Whyte said. “They’re not an invited species, but we have a lake in balance.”
However, quagga mussels aren’t a fisherman’s friend. “They are sharp enough to cut your line if you’re bottom fishing,” he said. They also cling to boats and docks like zebra mussels.
“But they haven’t done the damage to infrastructure like they thought they might have,” he said.
However, that could change.
“One of the problems with quagga mussels is they are on the bottom and they filter every toxin that goes through the lake. When fish start to eat them and birds eat fish, it could be like the E. coli outbreak we had in Georgian Bay.”
The concern is what the future might hold.
For now, Ginn and his team are taking quagga mussel samples at 40 sites in the lake, using a claw machine to dredge the bottom.