Biology Reference
In-Depth Information
18.
Counteradaptation and Integration
into the Biotic Community
“The history of evolution and biodiversity is fundamentally a history of the
evolution of species interactions. ...The more we learn about the diversity
of life and the structure of genomes, the more it appears that much of the
evolution of biodiversity is about the manipulation of other species—to gain
resources and, in turn, to avoid being manipulated.
—T
HOMPSON
(1999
C
)
The zebra mussel (
Dreissena polymorpha
) appeared in Lake St. Clair,
between Lakes Erie and Huron, in 1986. Since then, it has spread
throughout the North American Great Lakes and many other lakes and
rivers in the eastern part of the continent. By 1989, zebra mussels had
apparently colonized the northern shore of Lake Erie from Long Point
eastward. The closely related quagga mussel (
D. bugensis
) appeared in this
area somewhat later. When invasion of these mussels was recognized, an
extensive sampling program for mussels was initiated because of the eco-
logical richness of the bay area inside Long Point, Ontario, and its impor-
tance as a stopover area for migratory waterfowl (Petrie and Knapton
1999).
The first mussel sampling in 1991 revealed that almost 27% of sam-
pling stations were occupied by mussels and that Long Point Bay held an
estimated biomass of about 1,189 tons of mussels. By 1992, mussels
occurred at 80% of sites, and the bay's biomass had grown to 4,536 tons.
Beginning in 1992, stomach analyses of ducks killed by hunters were
245
