By Jacqueline Madill and Meaghan Murphy
Watch out! Zebra mussels may be coming to an area near you. Disturbing sightings of this invasive species on the Ottawa River has spurred the creation of a zebra-mussel citizen-watch programme in the Ottawa River watershed.
The discovery of zebra mussels (Dreissena polymorpha) in a new location on the Ottawa River was brought to the attention of André Martel, Ph.D., at Canadian Museum of Nature. This spring, Martel confirmed the arrival of the invasive zebra mussel on boats and anchors in Lac Deschênes, a reach upstream of Ottawa that we hoped would avoid invasion.
On July 10, 2015, a training session for the monitoring programme was held at the Ottawa Rowing Club as part of Ottawa Riverkeeper’s annual Riverwatch Meeting. Over 40 riverwatchers were trained by museum researcher Jacqueline Madill on how to distinguish zebra mussels from our native marine and native freshwater mussels, as well as how to conduct shoreline surveys. Important but not identifying characteristics: native marine mussels are scrumptious and native freshwater mussels are the best organisms for filtering water clean.
Martel and Madill designed a simple zebra-mussel collector, needed for estimating their settlement patterns: a standard cement block lowered into the water. At summer’s end, the number of adults that accumulated on the block is counted. This method allows comparisons to be made throughout the watershed with the help of many volunteers. A fine example of citizen science!
Zebra mussels arrived in the Great Lakes in 1986 from ballast waters of vessels from Europe. Their veliger larvae drift in water after spawning, subjected to current flow. A female zebra mussel can produce up to a million larvae in a single summer.
In two to three weeks, zebra mussels settle and attach with byssal threads to any hard substrate that they can find, such as rocks, plastic, shells and even other zebra mussels. In a river, the larvae can travel in only one direction, and downstream portions of the Ottawa River are in danger.
To travel upstream and to other bodies of water, zebra mussels require the assistance of humans. That is where we come in. Zebra mussels travel well on boats, trailers and vegetation caught in the motor, and they can live for several days out of water. We have to clean anything that can transport zebra mussels from one water body to another.
With citizen scientists tracking the distribution and movements of this invader, and everyone’s effort on boat washing, their spread upstream can be prevented. Let’s focus on critical regions within the watershed that are at risk.
Vigilance is important because we do not know of any way to get rid of these destructive pests once they are established.