Observational data set since 1855 from both Madison area lakes Mendota and Monona from the Wisconsin State Climatology Office and Nelson Institute for Environmental Studies
This activity reviews the concept of trophic cascades. Trophic cascades occur when predators reduce the abundance or change the activity of their prey, thereby allowing species in the next trophic level to increase in number. These indirect effects by the predator can trickle down (or cascade) to many lower levels of the food chain. In a classic example, sea otters protect kelp forests, sea otters protect kelp forests by controlling the abundance of urchins that graze upon the kelp. In the absence of otters, urchins consume most of the kelp and negatively affect other organisms that live in the kelp forests.
Trophic cascades have been described in numerous ecosystems ranging from kelp forests of the Pacific Ocean to arctic islands, to Central American jungles, to salt marshes. In this activity student use organism cards to build examples of trophic cascades based in different ecosystems, including several in Wisconsin!