OUIMET, C. Zoology Department, The University of British Columbia, ouimet@zoology.ubc.ca

 
MESOCOSMS AND THRESHOLDS IN ECOLOGICAL SYSTEMS: A WINDOW OF OPPORTUNITY IN RESEARCH.
 
The existence of alternative states had been relegated to the realm of computer modeling until the mid-1980s when field examples of ecological systems with discontinuous dynamics (thresholds) started to surface in increasing numbers. Although alternative states can often be uncovered in observational data, they cannot be understood from such data alone. Mesocosm experiments are required to isolate the mechanism at work. Furthermore, when multiple states exist in the dynamics of an ecological system, the mechanisms which allow a system to cross from state A to state B and those which allow the system to cross from state B to state A are different (hysteresis effect). Each threshold must be investigated independently. I present an overview of the current place of mesocosms in the study of discontinuous dynamics, including results from enclosure experiments on the zooplankton dynamics of oligotrophic lakes. Mesocosm experiments can reveal divergence in state under similar experimental conditions and similarities under different conditions, both of which are factors revealing the presence of thresholds. As more examples of thresholds in ecological systems come to light, mesocosm experiments will be a tool of choice to locate the thresholds and to deepen our understanding of the functioning of such systems.
 
Day: Thursday, Feb. 4
Time: 02:30 - 02:45pm
Location: Hilton of Santa Fe
 
Code: SS51TH0230E