PARENT SESSION
Contributed Oral Session 46: Predator - Prey Ecology: Communities and Environmental Impacts
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 519 B, Level 5, Palais des congrès de Montréal

Integrating energetics and interaction strengths: A modeling perspective.

Marshall, Kristin¹, Essington, Timothy¹, ¹ University of Washington, Seattle

ABSTRACT- While classically food web studies have been categorized by interaction webs or energetic webs, incorporating both types of webs into a theoretical approach to predicting interaction strength might provide a more complete understanding of natural food webs while also allowing for increasingly realistic predator dependency parameter inputs to ecosystem models. With this in mind, we have incorporated energetic information into a predator-prey model to evaluate the usefulness of energetic information (diet composition, consumption rates, and prey mortality rates) to predict interaction strength. Using predator-prey models with both Holling Type I and Type II functional responses and digestion constraints, we explored the energetic conditions that give rise to strong interaction strengths through simulations and evaluation of steady-state model conditions. Specifically, we performed a Monte Carlo analysis that drew parameter values from energetically plausible ranges, and explored the linkage between energetic linkage (expressed as percentage contribution to predator energy requirements) and interaction strength. Model analysis indicates the relationship between these two parameters is highly complex, and that in general, prey species that constitute a high percentage of predator diets typically are not strongly controlled by that predator. These findings suggest that simple assessments of predator food habitats are not only insufficient to predict interaction strengths, but generally provide misleading predictions.

Key words: interaction strength, energetics, predator-prey model