STUDENT INSTRUCTIONS

      Turn to your neighbor and first describe and then analyze Figures 2A, 2B, and 2C. Take your time with these graphs; make sure you understand the axes and what is being plotted before you attempt to analyze the data.

      Figure 2A shows changes in the biomass of microscopic animals (zooplankton) in the Hudson River water and in two types of clams that grow on the river bottom.

      Figure 2B shows changes in the mass of the smallest zooplankton, chlorophyll, and solids in the water.

      Figure 2C shows changes in river discharge, temperature, and how quickly the water is filtered by filter feeding animals.


Discuss the following questions:

• What are the major changes in the Hudson River after invasion by zebra mussel? Why did these changes occur?


• If you were to swim and snorkle in the Hudson now and in 1990, how would it look different now compared to then?


• Why did the researchers examine river discharge and temperature before and after the invasion? What question were they addressing by doing this?


• Overall in what ways has the zebra mussel altered the Hudson River? Can you list some likely negative and positive effects?