Ecological stoichiometry considers how the ratio of multiple limiting elements in organisms and their food influences individual growth and reproduction, rates of consumption, nutrient cycling, and community dynamics.  The threshold element ratio (TER), a fundamental tool of ecological stoichiometry, examines limitation of organismal growth by multiple elements, such as N and P.  The TER is the ratio of limiting elements at which growth is maximized.  Drawing on these ideas and physiological models of water budgets, we predicted a threshold resource ratio (TRR) for water:organic matter (hydration) of prey that influences rates of consumption by predators.  In this framework, consumption is predicted to be maximized at some intermediate ratio of water:organic matter (the TRR).  We then tested this prediction by feeding crickets with altered water:organic matter ratios to wolf spiders and examining consumption.
Results/Conclusions

We found patterns matching those predicted by our extension of theories of ecological stoichiometry and physiology, with significant variation across treatments (ANOVA, p=0.007).  Water is not often considered an important resource directly influencing animal communities.  Here we show that hydration of prey can influence consumption by predators and provide mechanistic hypotheses for this pattern, based on theories of physiology and ecological stoichiometry.  Research presented here was part of a collaborative project with a local high school student (PU) participating in an outreach program.