BACKGROUND

      Eutrophication (organic matter increase in water) is a crucial problem in marine and freshwaters worldwide. Coastal waters in particular receive large loadings of N and P (mainly from agriculture and sewage) which in turn stimulates growth of phytoplankton and macroalgae. This increase in primary production can result in anoxia and hypoxia (oxygen concentration > 2 ppm) when bacteria and other aerobes use up ambient oxygen to metabolize this pulse of organic carbon. “Fish kills” (large kills of fish and other animals) and death of corals and seagrasses can occur during anoxic events.

      The basic biological concepts manifested by eutrophication include nutrient uptake by primary producers, aerobic bacterial metabolism, and effects of low oxygen on aerobes. Even though students may understand these concepts separately, for many linking them to predict effects of nutrient enrichment in the Florida Bay and Keys is difficult. The jigsaw allows students to focus on each concept separately in one group and then in a second group they put the pieces together.