Description

• Dreissena polymorpha
• Has caused profound ecological changes in freshwater ecosystems where it is established, including losses of phytoplankton and microzooplankton
• Causes mortality of native clams and mussels
• Cost municipal and industrial water facilities millions of dollars to control
• If introduced into Montana will likely survive, become established and result in significant environmental and industrial damage
• Transported overland in bilges, livewells, motors and attached to boats and trailers

General Characteristics

• larvae not possible to see with naked eye
• newly settled larvae feel like sand paper on smooth surfaces
• juveniles are pepper corn size
• mussel with brown to black stripes
• adults can grow up to 2” long, typically are ¾” long

Links

Walleyes Unlimited of Montana- Zebra Mussel

Description

• Potamopyrgus antipodarum
• Spread via stocking operations, by recreational anglers, or possibly aquarium release
• Reproduces asexually and thus it only takes one to start a new population
• Found in lakes and rivers
• Can close operculum to avoid desiccation
• Out competes native snails and other invertebrate
• May impact fisheries by reducing food availability

General Characteristics

• range in size from a grain of sand to 1/8” long
• color brownish to bluish-green
• operculum covers opening of shell, which is on left
• densities reported over 500,000 per square meter!

Links

Walleyes Unlimited of Montana- New Zealand Mudsnail