- Widespread mercury contamination threatens aquatic ecosystem functions due to its capacity to bioaccumulate, biomagnify, and induce toxicity in food webs. Methylmercury (MeHg), the organic form of mercury, bioaccumulates more efficiently and tends to be more toxic than the inorganic form. One important impact of mercury exposure is inhibition of effective predator recognition and avoidance behavior. While there has been considerable research done on mercuric toxicity in aquatic species, research on invertebrates and aquatic communities is limited. We posit that dragonfly larvae are ideal bioindicators due to their relatively long lifespan, trophic position, and linkage of aquatic and terrestrial food webs. This study aims to quantify how MeHg exposure impacts larval dragonfly response to fish predators. Prior to predation assays, we dietarily dosed dragonfly larva with MeHg for eight weeks. We then quantified predator avoidance behavior in dragonfly larvae using a full-factorial 2×2 experimental design: high MeHg larvae and control larvae; fish presence and fish absence. The fish presence trials involved separating the fish and dragonfly with a mesh divider to allow for chemical, mechanical, and visual cues to be received. Each trial was video recorded for 40 minutes and later analyzed for dragonfly position and refuge use every 30 seconds. The resulting predator avoidance responses better characterize how environmentally relevant MeHg contamination might be imperiling dragonfly survival and altering dynamics of aquatic communities.