PARENT SESSION
Contributed Oral Session 93: Modeling: Movement, Populations, and Communities
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal
Individual-based models of small scale movement patterns: how palatable are our predictions?
Lemasson, Bertrand *,1, Haefner, James1, Bowen, Mark2, Frizzell, Kathy2, 1 Utah State University, Ecology Center, Logan, Utah, U.S.A2 Bureau of Reclamation, Denver, Colorado, U.S.A
ABSTRACT- An individual-based movement model is validated to assist conservation efforts at an estuarine fish diversion facility (TFCF) in Tracy, CA. The ibm operates at spatial (0.01 m) and temporal (0.5 s) scales that lie between those used by more traditional fish movement models. Movement decisions are based on fundamental bio-physical relationships and a categorization of the range of behavioral responses. Our primary objective is to provide validation procedures for small scale, spatially explicit ibms. Oncorhynchus mykiss specimens (mean size 9.9 cm) were filmed in a small scale physical model of the current field conditions, with the effects of turbidity necessarily removed. Behavioral assumptions of the model are classified into reaction distance, shifts in swimming behavior, and avoidance strategy (escape trajectory and average acceleration employed). Reaction distance corresponds with the assumed response distance (90% confidence). Predicted shifts in swimming behavior (acceleration profiles) are not statistically different from the observed data (Pearson's Chi-Square, P=0.8756). Observed escape trajectories reveal a relatively uniform distribution over the trajectory domain. Video analysis revealed both active C-start startle responses and passive avoidance strategies (mechanisms of minimum and maximum escape trajectories) that concur with model expectations of extreme events. Bio-physical relationships can therefore serve as a useful tool in bounding the variance expected in small scale movement patterns. Our approach provides useable constraints on our assumptions for this complex system, with a methodology that could be more directly applied in spatial studies involving simpler systems (e.g., dessert communities).
Key words: ibm, spatially explicit, validation, movement