Consultant's Report - Minnesota State Legislature

Mode of Life and Habitat
MINNESOTA DEPARTMENT OF NATURAL RESOURCES
Feasibility Study to Limit the Spread ofZebra Mussels from Ossawinnamakee Lake
Mackie (1991) described the mode of life of D. polymorpha as epifaunal, which refers to living
either on the sediment surface or on a firm substrate, such as a shell or other structure, on or
above the sediment surface. Zebra mussels are known to inhabit freshwater lakes and rivers
(Strayer 1991) but they also do well in cooling ponds, quarries, and irrigation ponds as well.
Research within North America has demonstrated that zebra mussels are capable of living in
brackish water or estuaries, where salinity does not exceed 8 to 12 parts per thousand (ppt)
(Nalepa and Schloesser 1993).
Dispersal Mechanisms
Numerous potential dispersal mechanisms oflarval and adult D. polymorpha have been reviewed
in the literature. These dispersal mechanisms have been divided into natural mechanisms (e.g.,
water currents, birds, insects, and other animals) and human-mediated or anthropogenic
mechanisms (e.g., artificial waterways, ships and other vessels, fishing activities, amphibious
planes, and recreational equipment). Generally, dispersal of zebra mussels is believed to occur
naturally primarily by currents that canoy plankton veligers (Mackie et al. 1989, Carlton 1993).
The "foot" is an extendible muscular organ located in the mid-ventral region ofthe mussel, and
its primary function is locomotion. Located within the foot is the byssal gland, which produces
secretions that are used to form byssa1 threads. The zebra mussel uses the byssal threads for
attachment to various substrates. As environmental conditions change, the zebra mussel has the
ability to detach their byssal threads from the substrate and can "move" either directly via the
"foot" or passively as water currents move the mussel to a more suitable location or substrate
(Frisina and Eckroat 1992).
Geographic Distribution
As, stated previously, zebra mussels were first observed within North America in Lake St. Clair
in 1988 (Ram and McMahon 1996). From their apparent arrival in 1998 through the present,
zebra mussels have spread throughout all the Great Lakes and St. Lawrence, Mississippi,
Tennessee, Hudson, and Ohio River Basins (USACE 2005, US Department ofthe Interior 2000).
Figures IV-2 and 3 illustrate the initial infestation in 1988 and the subsequent spread of zebra
mussel distribution in 1999 within North America.
IV-3 Review of Zebra Mussel (Dreissella polylIlOlpha) Species