Underwater Invaders

“Zebra” and “quagga” may sound perfectly paired to star in a kids book, but their presence in the Basin is anything but playful.

5 minute read

“Zebra” and “quagga” may sound perfectly paired to star in a kids book, but their presence in the Basin is anything but playful.

Walleye and northern pike, two invasive freshwater fish, have already wiggled their way into local rivers and lakes, raising local concern as they chomp through food sources and alter the balance of aquatic ecosystems. And although the quagga and zebra (mussels, that is) have not yet showed up in British Columbia, the havoc they’ve wreaked in other regions has people in the province rallying to keep them at bay.

Zebra and quagga mussels, dubbed ZQM by those in the field, are almond-sized mollusks with striped shells. Adult ZQM latch firmly onto underwater surfaces with thin cords called byssal threads (imagine a beard dipped in crazy glue), where they live for up to five years. The theory is that zebra mussels first arrived in North America in the 1980s when trans-Atlantic freight ships released ballast water at port in the Great Lakes region. Swirling about in the discharged water were stowaways from Eastern Europe: zebra mussels. It would only have taken a single tank and two mussels—one male and one female—to pioneer a population boom.

The first colony was found in Lake St. Clair, east of Detroit, Michigan. Three years later, zebra mussels had taken over parts of Lake Erie, with densities reported at up to 700,000 mussels per square metre. Thirty years later—and now with their cousin quagga in tow—the tiny bivalves have spread throughout Ontario and Quebec, turned up in Lake Winnipeg and been found in waters of 34 U.S. states. In spring 2015, two dead zebra mussels were found clinging to a dock near the Red River in Manitoba.

A map of ZQM in North America shows a scourge of red dots clumped around the Great Lakes, clotting waterways that feed out of the epicentre and speckling hundreds more lakes and rivers with new data points noting their arrival. Yet, as of today, British Columbia remains mussel-free.

Many organizations hope it will stay this way. The Okanagan Basin Water Board, for example, estimates costs to Okanagan communities of over $43 million per year if the mussels were to establish themselves in Okanagan waterways.

The Columbia Basin’s Khaylish Fraser is also concerned. As the aquatic invasive species program co-ordinator with the Central Kootenay Invasive Species Society, Fraser understands the ramifications of a mussel outbreak. “Our lakes and rivers are at risk,” she says.

“The ecology and economy of the Columbia Basin would be seriously impacted.”

In the span of a single year, one female mussel can spawn millions of eggs. After two or three days, the eggs become larvae, moving with the current for several weeks, sometimes travelling hundreds of kilometres before they take up residence somewhere. For the first year they creep along a surface with their mollusk feet until they finally settle down to stay.

Between the two species, ZQM can cover any surface. Docks, boat hulls, pipes and aquatic plants become encrusted with layer upon layer of mussels filter-feeding for phytoplankton, stripping the lake or river of food and excreting liquid feces.

It would only have taken a single tank and two mussels to pioneer a population boom.

According to Fisheries and Oceans Canada, the ecological impacts of ZQM include: an increase in toxic algal blooms, degradation of spawning grounds, lowered chance of fish egg survival and less food available for fish. These could lead to big drops in fish populations, including those favoured by anglers, such as trout and kokanee. Also, as the mussels filter out a lake’s plankton, the water becomes remarkably clearer. Sunlight then travels deeper, and aquatic vegetation, including the invasive milfoil, has a better chance of survival. A few other problems that come with ZQM are increased community water treatment costs, clogged community water-intake pipes, botched agricultural irrigation systems and exorbitant maintenance costs for hydroelectric and drinking water facilities.

For example, Ontario Power Generation had to spend between $15 to 18 million to retrofit its facilities in response to a zebra mussel infestation. And in some areas, thick carpets of razor-sharp mussels have covered the once-pebbly or -sandy beaches, making it nearly impossible to swim or walk barefoot. Meanwhile, the mussels continue to multiply.

“Just one boat carrying live mussels or their larvae across the border into BC could set things off,” Fraser warns. QZM are small and their larvae are even smaller, invisible to the naked eye, which makes detection tricky.

Part of Fraser’s job is to help coordinate the aquatic efforts of the four invasive species societies that currently operate in the Basin: the East Kootenay Invasive Plant Council, Central Kootenay Invasive Species Society, Columbia Shuswap Invasive Species Society and Northwest Invasive Plant Council. With numerous lakes and rivers, our region and the province as a whole are popular destinations for water enthusiasts, who drive a huge number of boats here from the States and other provinces. This means vigilance about detection is key.

Mussels could cost Okanagan communities up to $43 million a year.

In July 2015, a new partnership was announced. To increase the chance of finding mussels before they enter BC’s waterways, British Columbia’s Ministry of Environment Invasive Mussel Defence Program, Columbia Basin Trust and the invasive species societies banded together to streamline efforts and resources. With a $275,000 contribution from Columbia Basin Trust, $70,000 from Columbia Power Corporation and $15,000 from FortisBC, the number of Conservation Officer Service inspection teams who stop, check and clean watercraft has been doubled from three to six.

The teams are strategically based out of Cranbrook, Invermere, Nelson, Penticton and Valemount, and move between border locations, focusing on high-traffic routes to ensure all watercraft—including kayaks, canoes and stand-up paddleboards—are mussel-free. And yes, there have been a few close calls. In addition to these stations, proactive efforts also include water sampling to test for ZQM larvae and outreach campaigns such as the catchy Clean, Drain, Dry program.

As ZQM populations grow outside of the province, so does the threat of a local introduction. How ironic that the original quagga went extinct in the late 19th century (it was a type of zebra—the mammal, not the mussel), whereas these ones are so prolific. To date, there is no viable solution to the ZQM problem beyond trying to stop them from hitching a ride into our region. And once established, they’ll likely be here to stay.

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