What impact or changes do you think this invasion of zebra mussels will have on the native species living in the Hudson River ecosystem? (Hint: Think about what it means to be the only freshwater mussel species that can attach itself toobjects.)

polymorpha is a small bivalve that originated from the Caspian Sea region, In mid 1980s the Zebra Mussels moved to North America in the ballast water of a ship.

They took over the

Great Lakes and the waters draining them. It is speculated that the Zebra mussels will eventually

move to most of the waters in North America with the exception of waters that are too warm or too saline for them to survive.

They were first discovered in the Hudson at very low densities in 1991, spreading rapidly that by 1992 they can be found throughout the river, with biomass that was greater than the combined biomass of all

other consumers viz; fish, zooplankton and bacteria, in the river.

Their densities can reach over

100,000 individuals per square meter. Because they are so many, they are able to filter all of the

water in the freshwater portion of the Hudson River every 2-4 days.

Whereas the native mussels could filter the water only every 2-3 months.

Zebra mussels are suspension feeders, eating

phytoplankton, small zooplankton, large bacteria, and organic detritus by filtering the water and straining out the edible material.

Now, because they filter small

organisms and organic particles out of the water at very high rates. (Very efficient filter-feeders)

Phytoplankton and zooplankton which form the base of the aquatic food web, as many animals depend on them for survival, this balance is tilted.

This has brought great changes and effects on the Hudson Ecosystem. The food web changes that the mussel has caused compare in magnitude to disturbances in other aquatic ecosystems caused by toxins, nutrient pollution, or acid rain. and have been found. These mussels were most likely

brought to those areas by careless human activity.

Furthermore, most of the species on the Hudson river will be endangered and some must have gone into extinction and this is due to the speed with which the Zebra mussels feed on them.