Western Invasion by Zebra and Quagga Mussels in North America

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Western Invasion by Zebra and Quagga Mussels in
North America

• David K. Britton, Ph.D.
• U.S. Fish Wildlife Service

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Two Invading Species

• Zebra Mussels
• Driessena polymorpha

Quagga Mussels Driessena rostriformis bugensis
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Biology

• Genus Dreissena has seven species
• Two are invasive in North America
• Freshwater Bivalve Mollusks (clam)
• Adults about 1 inch long
• Highly variable coloration patterns, generally
  with dark light stripes
• Filter Feeder
• Extremely Prolific
• Females can release over 100,000 eggs per year
• Live about 4 -5 years
• Planktonic as larvae
• Generally sessile as adults

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Physiological Tolerances
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Life Cycle

• Planktonic Larval Stage (veliger)Generally
  Sessile (non-motile) as Adults

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Adults

• Adults attach to any hard surfaces with byssal
  threads
• Typically forming dense clusters

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Encrustation
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Native Range
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Initial Discovery
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Trailered Boats

• Mussels can attach to weeds that can be carried
  by boats and trailers
• Bilge, bait and live wells can carry mussel
  larvae
• Mussels can attach to hulls and anchor chains

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Desiccation Resistance

• Zebra mussels can live out of water for more than
  two weeks under ideal conditions
• High humidity
• Low Temperatures

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Impacts Consequences

• Environmental damage
• Habitat alteration
• Food web disruption
• Impacts to native species
• Native Mussels
• All but gone in St. Clair Western Lake Erie
• Up to 10,000 zebra musselson a single unionid
  clam

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Impacts Consequences

• Economic damage
• Industrial and raw water fouling
• Municipal Water Supplies
• Hydro-electric Stations
• Fossil Fuel Power plants
• Management control costscan be in the
  millions or billions of dollarsannually

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Impacts Consequences

• Health Issues
• Bioaccumulation
• Concentrate heavy metals and other contaminants
• Sharp shells cut hands and feet

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Summary

• Zebra and quagga mussels are among the worst
  aquatic nuisance species in North America
• The Invasions continuesalthough spread has been
  slow for a decade or so, the pace should quicken
  now that both species are in the west.
• Intentional transfer of infested waters to areas
  where natural sources of freshwater are scarce
  has spread invasive mussels quickly.
• Trailered boats will likely the primary overland
  vector into additional non-infested water systems
  in the West.