By Jacqueline Madill and Val Tait
Amid the chirping of crickets, calls of children to their mothers and gentle lapping of waves, a team from the Canadian Museum of Nature headed past the beach at Petrie Island in Ottawa in search of aquatic invertebrates.
The Friends of Petrie Island had invited the Canadian Museum of Nature to introduce local invertebrates to visitors on River Day, July 19, 2014. Our invertebrate team—Jacqueline Madill (Senior Research Assistant), Val Tait (Research Associate) and Emily Cooper (student from the University of Ottawa)—needed to perform a quick survey on the shores of the island before the presentation. We were fortunate to have one of those amazing hot summer days, with a refreshing breeze coming off the Ottawa River.
In no time at all, despite poor visibility in the water, we found three species of freshwater mussels nestled between aquatic plants: the eastern lampmussel (Lampsilis radiata), the pocketbook (Lampsilis cardium) and the eastern elliptio (Elliptio complanata). Our team could locate them fairly easily by feeling with our hands and feet because the mussels were happily feeding with their shells poking above the sand.
At the other sites, we caught swamp lymnaea snails (and other snails), fingernail clams, water striders, beetles, amphipods, isopods and chironomids. Although this was not a quantitative study, the diversity of aquatic invertebrates at Petrie Island was impressive. Every specimen was healthy and the best news was that no zebra mussels were found on that day.
All the invertebrates were displayed at the River Day activities, alongside the GeoCaching exhibit and the Ottawa Riverkeeper. Young visitors laughed at the spiralling whirligig beetles and watched fascinated as amphipods reached surprising speeds while doing laps around the tray, bypassing sediment and other invertebrates. The biggest mussel, a fatmucket (Lampsilis siliquoidea), was very cooperative, lying on its back, opening its shell, extending its foot, displaying siphons and papillae. It was the star, wowing visitors who had never seen mussels in action before.
The beautiful Ottawa River and its tributaries are a resource that connects the National Capital Region. There is another type of linkage that most people do not know about: the amazing relationship between freshwater mussels and their host fish.
Visitors did not know that freshwater mussels are in decline. We stressed that during shoreline clean-ups, citizens need to protect our native freshwater mussel populations because, as they feed, they are filtering the water continuously and help to keep the river clean. We also need to recognize that the invasive zebra mussel is quite different and is responsible for killing many native invertebrates. Dense populations can also clog water intakes and modify habitat, thereby changing the availability of food for young fish. It is important not to confuse native mussels and the zebra mussel—to know the good guys from the bad guys.
Petrie Island is such a beautiful location and many visitors to the area enjoy it on a regular basis. “Farewell”, we thought fondly as Emily carried our live invertebrates back to their watery homes.