ZEBRA MUSSELS (Syllabus: GS Paper 3 - Env and Eco)

Context: For the first time, zebra mussels—an invasive species known for destroying aquatic ecosystems have been discovered in the Colorado River, a crucial waterway in the American Southwest.

Zebra Mussels

• About: These are an invasive, fingernail-sized mollusk.
• Scientific Name: Dreissena polymorpha
• Distribution: They are native to the Caspian and Black Seas, south of Russia and Ukraine.

oThey entered the Great Lakes of North America in the late 1980s through ballast water discharged from ships.

• Since then, they have spread through much of eastern Canada and the United States.
• Habitat: They live underwater, attached to natural and manmade substrates such as rocks, wood, plants, native mussels, pipes, docks, boat lifts, swim rafts, moored watercraft, and other debris.
• Identification: They are easy to identify with their distinct, flat-bottomed ‘D’ shape to their shells and black, zigzag stripes against a cream background.
• Size and Lifecycle: They grow around two inches long at most, and are microscopic in their larval stage, known as a “veliger.” They are short-lived (between two and five years) and begin reproducing at two years of age.

Impacts

• They are filter feeders that attach themselves to virtually any surface. Females can release up to one million eggs each breeding season.
• They disrupt food webs by wiping out phytoplankton. Zebra Mussels are especially harmful to native mussels, many of which are species at risk. They outcompete these species for food and will attach themselves to native mussels, suffocating them.
• Their massive clustering on water-intake valves and pipes, bridge abutments, and other structures can cause severe commercial damage.