Mississippi Valley Field Naturalists
April 5, 2013
Jackie shows mussels at next MVFN lecture
The Mississippi Valley Field Naturalists’ (MVFN) 2012-2013 public lecture series, Nature Beneath Our Feet, continues April 18 with the seventh presentation, ‘Freshwater Mussels of the Ottawa Valley.’ You do not need to be an expert to enjoy the presentations, just possess a curiosity or appreciation for wild nature. Cottagers, hunters, fishermen, canoeists, hikers, campers, artists and seasoned field naturalists alike will find something to interest them as we explore nature. Refreshments are offered at each lecture.
For this lecture, we switch to the aquatic realm beneath our feet with a presentation by Jackie Madill, senior research assistant with the Canadian Museum of Nature. You will have an opportunity to see first hand her collection of shells from mussel species we are likely to find in our area. As a malacologist, she specializes in Canadian freshwater mussels. She also is a hirudinologist, having a love for Canadian leeches. (In addition to her scientific expertise, please note that Ms. Madill is highly allergic to scented products such as perfume, soap, and shampoo. Before attending her presentation, MVFN asks that you not put on or use these products.)
Mussels belong to the group Mollusca which also includes snails, slugs, clams, scallops, oysters, squid, and octopuses. All these organisms have in common a soft body, no backbone, a muscular foot for crawling or burrowing, and a mantle. In mussels, the mantle produces a pair of hinged shells (often people refer to them as clams).
Among aquatic invertebrates, mussels are the longest-lived (many decades) and the largest, reaching 20 cm (8 in.) in length! They can be aged approximately by counting the growth rings on their shells.
Did you know that close to one-third (300) of the world’s mussel species occur in North America? Of the 55 species that occur in Canada, 41 are found in Ontario. In addition, we also have the zebra mussel, native to the Caspian Sea. It was introduced in ballast water released into Lake St. Clair in the mid-1980s and has spread throughout eastern North America. It has contributed to making freshwater mussels the most endangered organism group in North America. In Canada, more than half of our freshwater mussel species require conservation action.
Although mussels are found in many aquatic habitats, such as rivers, ponds and streams, they are hidden beneath our feet as names like pink heelsplitter, white heelsplitter, and creek heelsplitter suggest. Many, however, have been given more amusing names: rainbow, deertoe, rayed bean, hickorynut, threehorn warty back, snuffbox, mapleleaf, pimpleback, and elephantear. A tremendous pocket field guide, Photo Field Guide to the Freshwater Mussels of Ontario, was published in 2005 by the St. Thomas Field Naturalist Club.
In the same way beavers can be thought of as ecological engineers, mussels are known as ‘living filters.’ In their natural unpolluted state, beds of aquatic habitats can be carpeted by mussels. Mussels fed on algae, bacteria, and detritus that they filter from the water with their gills. In turn they are food for mink, otter, raccoons, and muskrats as well as some fish and birds. As filter-feeders, mussels are sensitive to pollution and habitat alteration which makes them good indicators of environmental quality.
Out of sight, but not out of mind—ouch! Prepare to look for mussels on your next aquatic outing by learning to recognize our common species. Mark your calendar “MVFN mussel show, NO PERFUME” for April 18, 2013, when Jackie Madill will present Freshwater Mussels of the Ottawa Valley. This event takes place at 7:30 pm at Almonte United Church, 106 Elgin St., Almonte. All are welcome ($5 fee for non-members). For further information please contact MVFN’s Program Chair Cathy Keddy at 257.3089.