Unfortunately, the zebra mussel is here to stay in many of Ontario’s lakes and river systems. Conservationists advocate measures to keep them from spreading, such as thwarting reproduction, manually removing them, placing tighter restrictions on ballast-water releases from foreign vessels and educating recreational boaters about cleaning zebra mussels off their boats. It is important that we increase our knowledge of the biology, behaviour and genetics of our native mussel species and pass that knowledge on to the public, who must be a part of any strategy to preserve unspoiled habitat, restore or create new refuges for native mussels, augment existing populations and reintroduce threatened species to their historic living areas.
Study has begun, but much more is needed. Morris is most intrigued by the way the wavy-rayed lampmussel interacts with its host fish, the smallmouth bass – a key piece of the knowledge puzzle biologists need to understand to enhance the chances of mussel survival. For the past three summers, he and his research team of students from the University of Guelph have donned chest waders and travelled to this site once a week to spend hours surveying the river bottom with underwater viewers that look like red traffic cones. The researchers count mussels, recording species, determining their sex, measuring them, photographing and tagging them with tiny numbers affixed to the shells with glue. Shells and occasionally live mussels are taken back to the university’s research lab for further study. “They are truly a remarkable example of evolution,” says Morris. “Part of our focus has been on the complex lures this species has evolved to attract the smallmouth bass. The mussel actually mimics a small minnow as one way to get the attention of the predatory smallmouth. When the smallmouth tries to feed on the lure, the female mussel releases her immature young into the mouth of the fish and they become parasitic, living on the gills for a few weeks while theyoung develop.”
The lack of general understanding about freshwater mussels is definitely out of proportion with the importance of these species to the healthy functioning of ecosystems. “Freshwater mussels are more than just living rocks under the water,” says Dave Zanatta, a Canadian malacologist. Now at the University of Central Michigan, Zanatta researches genetic factors in the survival of mussels.
Researchers are fascinated by the complexity of freshwater mussel behaviour and biology, a complexity most of us never imagined. Morris, Zanatta and their colleagues, a small but passionately dedicated corps of mollusc experts and boosters, are working hard to change our lack of awareness. Research teams in both Canada and the United States have documented the disastrous impact of the zebra mussel. Still, there is much the scientists do not understand, and little is known about the nature of the mussel population in many areas of the province. So each year, about 20 mollusc researchers from around the province select a body of water in Ontario and spend a weekend surveying its mussels. This year, the Nottawasaga River near Orillia was slated for survey, but the trip was cancelled when water levels rose to dangerous levels at the time of Hurricane Ike.
That research group includes Morris and Zanatta, as well as Kelly McNichols of the University of Guelph research lab; Daniel Spooner of Trent University, whose research is helping to uncover the secret lives of bivalves, answering big questions about how each species’ biology affects water quality in both forested and agricultural areas, as well as how species co-exist; and Fred Schueler, who in 2006 uncovered living eastern pondshells, a species severely affected by the zebra mussel, in the Lyn Creek watershed near Brockville.
Schueler, a naturalist specializing in leopard frogs, became hooked on monitoring and exploring the world of mussels in the mid-1990s, working with André Martel of the Canadian Museum of Nature to determine the extent of the spread of zebra mussels in eastern Ontario. A trip with Schueler to the fast-flowing waters of the Rideau River at Andrewsville shows the problem all too graphically. Schueler,in duct-taped wading shoes, walks into the thigh-deep water,stares down and fills a green garbage bag with specimens.Hethen wades back and lays them out on rocks along the bank. Of the couple of dozen examples of native species in his catch, such as the eastern elliptio, only two are living.The rest are empty, eroded shells, to which clusters of zebra mussels have attached themselves, depriving the native mussels of oxygen and food. He says that, back in 1995, though zebra mussels were beginning to encroach, “I would have said this was one of the best spots to come and see native mussels in eastern Ontario.” In less than a decade the invaders had almost completely destroyed the native populations in the area.
“Almost” being the operative word. As we prepare to leave the Rideau, Schueler throws the two live mussels back into the water. Will they and the millions of other Ontario mussels currently in peril survive? If they don’t, it won’t be for lack of concern, hard work and advocacy on the part of agrowing number of committed researchers.
“We are making some progress,” says Morris. The provincial freshwater mussel recovery team is midway through its five-year strategy for monitoring and restoring Ontario’s endangered mussel species. He points to the wavy-rayed lampmussel as a conservation success story in the making. Documentation shows its population declined through the 1970s to the 1990s, and the species may be extirpated from the Great Lakes. But today in the Grand River, it is the dominant mussel species. Soon COSEWIC will re-evaluate the status of the wavy-rayed lampmussel and might even move this species from the “endangered” category to “threatened” or a category of even lower risk. Morris attributes the species’ increasing population since the mid-1990s to the “general cleanup of the watershed,” which includes better agricultural land management and improved sewage systems in urban areas. “Can we bring every species back from the brink? Probably not,” says Morris. “But, for some, I truly believe we can make a difference.”