The last ten years have seen a host of new results in the field of nonlinear dynamics, most notably regarding the phenomenon called chaos. Many recent results have come from mathematicians and from theoretical and experimental physicists; yet much of the early work was motivated by issues in population dynamics. A recurrent theme of this recent resarch is that seemingly random fluctuations often occur as the result of simple deterministic mechanisms. Hence, much of the recent work in non-linear dynamics has centered on new techniques for identifying order in seemingly chaotic systems. These techniques when applied in ecology have led to new insights for several systems, most notably various childhood epidemics. To determine the robustness of these techniques, chaos must, to some extent, be brought into the laboratory. Preliminary investigations of the forced double-Monod equations, a model for a predator and a prey in a chemostat with periodic variation in inflowing substrate concentration, suggest that simple microbial systems may provide the perfect framework for determining the efficacy and relevance of the new nonlinear dynamics in dealing with complex population dynamics. This proposal will provide a thorough examination of the mathematical properties of the forced double-Monod model and an experimental investigation of the self- same system.
