Zebra Mussel Banquet

From January, 1995 (update #23)

PORT ROWAN, Ont. - Rapidly proliferating zebra mussels may cause headaches for humans, but they're providing a bountiful banquet for some hungry ducks in Lake Erie. In fact, at least two waterfowl species, the Greater and Lesser Scaup, have found the mussels to be such an appealing food that the birds have altered their migration and wintering routes in order to feed in Lake Erie, according to Richard Knapton, research director of Long Point Waterfowl and Wetlands Research Fund. Knapton studies waterfowl around Long Point, a thin peninsula jutting into northwestern Lake Erie from the Canadian shore. He reports that zebra mussels now make up nearly 90 percent of the two scaup species' diets. "The birds are targeting the mussel even though there seem to be fairly good amounts of their native food available," Knapton said. Scaup traditionally migrated across Lake Ontario and the upper reaches of the St. Lawrence River on their way to Chesapeake Bay. The route recently shifted westward. Consequently, Lake Erie scaup populations have grown tenfold since the late 1970s, Knapton said. "It's tempting to correlate that increase with the invasion of zebra mussels," he added. Zebra mussels also are inadvertently helping feed another Lake Erie waterfowl species - the canvasback duck. Because zebra mussels feed on plankton, they clear the water column, which allows sunlight to penetrate to greater depths. In Lake Erie, that extra light encourages the growth of aquatic plants like wild celery - the canvasbacks' major food source. Knapton surmises that the mussels' presence may help the canvasback, a species that has experienced a serious continent-wide population decline this century due to loss of breeding habitat, hunting pressure and degradation of its staging and wintering areas. However, duck predation on zebra mussels is unlikely to eliminate mussels from an area, according to an article in the March 1994 issue of Ecology, written by Diana Hamilton and colleagues at the University of Western Ontario. The authors concluded that it's "unlikely that they (ducks) will cause long- term reductions in zebra mussel populations." The authors said that "overall, ducks had little lasting impact on mussel populations, but mussel abundance may have determined duck concentrations" at their study site at Point Pelee in western Lake Erie.

ID: 199501-7.

The Zebra Mussel Update was a 4- to 8-page quarterly national newsletter published by the University of Wisconsin Sea Grant Institute from May 1990 through May 1997. The ZMU documented the spread of the zebra mussel -- an exotic nuisance mussel -- through North America's freshwater environments, especially the Great Lakes, and on efforts to control it.