Water quality and fisheries resources are dependent on the dynamics species interactions within fresh water lakes, yet little is known about how warmer temperatures (>25 C), in conjunction with food abundance, affect interactions of aquatic species. This research will explore interactive effects of elevated water temperature, up to 30 C, and food abundance on species interactions in a model planktonic food web. This three trophic-level food web includes a primary producer, 2 crustacean grazers, and one predator, each can be easily cultured or maintained in the laboratory. Effects of temperature, food abundance, and interactions of these conditions will be evaluated using a series of single and two-species experiments performed on members of the first two trophic level. Populations growth rates of the primary producer, loss rates caused by each grazer species, and the fecundity and survival of each grazer will be evaluated in different temperature/food abundance treatments. Results of experiments will be used to parameterize a simulation model which will project the outcome of species interactions under a wide variety of environmental conditions, Subsequent research will test these predictions, extend the model to include 3 trophic levels, and investigate how rapidly cladoceran grazers evolve in response to thermal selection pressures. Results will 1) aid in biotic assessments of elevated temperature, 2) establish a model food web for evaluating environmental effects on species dynamics, and 3) allow evaluation of the relative magnitude of higher order interactions in communities that are environmentally stressed.
