Are these results surprising? At least four non-mutually exclusive reasons indicate the answer is no. First, it is not clear whether shredding of leaves by limnephilid Anomalocosmoecus indeed facilitated food acquisition by Hyalella, although Hyalella’s mouthparts most likely make the species a less effective shredder of tough litter. Second, the argument made by Fuge`re et al. (2012) deviates substantially from situations considered in plant ecology. It is conceivable, for example, that the degree of competition, rather than facilitation, increases with decreasing food quality (defined here as stress), because patches of palatable and nutritious food, especially patches colonized by fungi (Suberkropp 1992; Chung & Suberkropp 2009), are scarcer on recalcitrant litter. Third, tests of the stressgradient hypothesis have produced mixed results even in plant ecology (Malkinson & Tielbo¨ rger 2010), suggesting that the postulated mechanisms are not universal. Fourth, the hypothesized interactions between the two species were limited to competition and facilitation. However, cannibalism and intraguild predation, which do not occur in plant communities, are common interactions among some detritivorous caddisflies (Klemmer et al. 2012) and amphipods (MacNeil & Dick 2012). Therefore, because death (predation) arguably has stronger consequences than hunger (competition), and mobile animals can more easily escape unfavourable environmental conditions than plants, species neighbouring effects that alleviate stress might not be as important for animals as for plants. Overall, this suggests that outcomes depend not only on specific context and associated mechanisms but also on how biodiversity effects at different trophic levels (e.g. consumers vs producers) are assessed.