The ecology of lakes and ponds depends strongly on the activity of zooplankton, small swimming animals about the size of a grain of rice. These animals are a main part of the diet of young fish. They also keep natural waters clean of algae. Daphnia occupy a key position in the food chain of lakes. They are the main animal that passes energy from algae to fish. When Daphnia are scarce, water quality suffers. Recent research on the biology of these small but key organisms suggests that their swimming behavior and where they live in a lake depend partly on biochemical compounds produced by fish and other predators. Dr. Dodson's research plans to identify at least one of the chemicals and test the ability of Daphnia to avoid predators based on detection of these chemicals. This research will also have relevance for management of aquatic resources, such as those situations in which game fish are stocked into lakes in order to have the ultimate effect of increasing the abundance of zooplankton and reducing the amount of algae.
