In partial support of the stress-gradient hypothesis, Fuge`re et al. (2012) find that caddisfly–amphipod interactions shift from competitive to neutral with increasing stress levels defined along their resource-quality gradient. However, no support was found by Fuge`re et al. (2012) for the main feature of the stress-gradient hypothesis: that facilitation is important in high stress environments. A small literature survey conducted in parallel to the experimental study also provides mixed outcomes.