Antipredator behavior in human-altered environments


Beyond our work on prey responses to novel predators, my lab has also looked at how other anthropogenic stressors have affected antipredator behavior.

a. Pesticides and antipredator behavior. One focus has been on how very low, supposedly sublethal concentrations of pesticides (many of which are endocrine disruptors) can interact with predation risk to have major impacts on species interactions that influence prey behavior and survival.  Experimental studies examining short and long-term effects of pesticides on amphibian prey behavior found that concentrations that are orders of magnitude below lethal levels can cause reductions in antipredator behavior that can prove lethal to prey (Rehage et al. 2002; Rohr et al. 2003a; Rohr et al. 2003b). The importance of pesticide-induced reductions in antipredator behavior should depend, however, on the susceptibility of predators to the same pesticides.  Notably few studies have looked at effects of chemical contaminants on both predators and prey.  That is, studies on prey usually expose prey but not predators to contaminants, and vice versa for studies on predators.  My lab examined simultaneous effects of contaminants on predators and prey.  Furthermore, most natural systems have multiple predators and prey, often with 3 or more trophic levels.  Pesticide effects might thus both depend on and influence multi-species interactions – trophic cascades, multiple predator effects, intraguild predation – via a combination of direct, lethal and trait-mediated (e.g., behavioral) effects.  An early conceptual note in TREE on this issue (Sih, Bell & Kerby 2004c) was expanded into a conceptual overview paper in TREE on how pesticide impacts are analogous to predator impacts on individuals, populations and communities (Rohr, Kerby & Sih 2006).  The work outlined above was supported by an EPA grant with Rohr (now an associate professor at Univ. S. Florida) and others, and produced a recent PhD (Jake Kerby, now an assistant professor at Univ. S. Dakota).

b. UV light and antipredator behavior. Parallel work by a PhD student (Tiffany Garcia, now an assistant professor at Oregon State) examined how exposure to ultraviolet light interacts with elevated temperatures and predation risk to influence color change, depth and shelter use in larval amphibians (Garcia & Sih 2001; Garcia & Sih 2003; Garcia, Stacy & Sih 2004).

c. Ocean acidification and antipredator behavior. Most recently, I was a fringe member via a postdoc in my lab, Maud Ferrari, for studies on how ocean acidification (via elevated carbon dioxide levels) disrupts antipredator behavior and learning in larval coral reef fish in the Great Barrier Reef (Ferrari et al. 2011; Ferrari et al. 2012).  Most notably, species differed considerably in how much their antipredator responses were disrupted by high carbon dioxide levels.  I hope to expand my participation in that project in the not too distant future.