See laboratory handout for detailed instructions. In brief:
Fill 7 BOD bottles with Chorella culture.
Measure the dissolved oxygen content of one of the bottles and record this as initial.
Place zebra mussels in 2 BOD bottles.
Place local native bivalves in 2 other BOD bottles.
Make sure there are no air bubbles at the top of the bottles and secure the lids.
Label the 6 bottles.
Wrap one zebra mussel bottle, one native bivalve bottle, and one algae bottle in aluminum foil so no light can get into the bottles.
Place the bottles under the grow lamp for 24 to 48 hours.
Measure the dissolved oxygen content of all six bottles.
Calculate the gross productivity (light bottle – dark bottle) and the net productivity (light bottle – initial bottle) for the algae alone, with zebra mussels, and with native bivalves.
Students write a formal lab report, including a graph of results and a discussion of the impact of zebra mussels on primary productivity compared with native bivalves’ impact and predictions of what will happen to algae populations in an invaded ecosystem.