Western Invasion by Zebra and Quagga Mussels

in North America

Western Invasion by Zebra and Quagga Mussels

in North America

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

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

Two Invading SpeciesTwo Invading Species

Zebra MusselsDriessena polymorpha

Zebra MusselsDriessena polymorpha

Quagga Mussels Driessena rostriformis bugensis

Quagga Mussels Driessena rostriformis bugensis

BiologyBiology• 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

• 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

Physiological TolerancesPhysiological TolerancesZebra Quagga

Salinity < 5 ‰ < 5 ‰

Temperature < 30 C < 28 C

pH 7.4 - 9.5 7.4 - 9.5

Calcium > 25 mg/L > 25 mg/L

Emersion Minutes to weeks Minutes to weeks

Depth Surface to 100 m Surface to >100 m

Oxygen > 25% air sat. (>2 mg/L)

More tolerant

Life CycleLife Cycle• Planktonic Larval Stage (veliger)

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

Generally Sessile (non-motile) as Adults

AdultsAdults• Adults attach to any hard surfaces with

byssal threads

• Typically forming dense clusters

• Adults attach to any hard surfaces with byssal threads

• Typically forming dense clusters

EncrustationEncrustation

Native RangeNative Range

Initial DiscoveryInitial Discovery

Trailered BoatsTrailered 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

• 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

Desiccation ResistanceDesiccation Resistance

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

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

Impacts & ConsequencesImpacts & 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 mussels

on a single unionid clam

• 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 mussels

on a single unionid clam

Impacts & ConsequencesImpacts & 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

• 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

Impacts & ConsequencesImpacts & Consequences

• Health Issues– Bioaccumulation

• Concentrate heavy metals and other contaminants

– Sharp shells = cut hands and feet

• Health Issues– Bioaccumulation

• Concentrate heavy metals and other contaminants

– Sharp shells = cut hands and feet

SummarySummary

• Zebra and quagga mussels are among the worst aquatic nuisance species in North America

• The Invasions continues—although 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.

• Zebra and quagga mussels are among the worst aquatic nuisance species in North America

• The Invasions continues—although 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.