Background/Question/Methods
Climate change alters multiple physical drivers that act concurrently on ecological communities. Growing evidence suggests that non-additive effects between multiple drivers are widespread. Most of the evidence, however, is based on the responses of individual species, which is problematic because community responses to environmental change also depend on interactions between species. To address this knowledge gap, I experimentally manipulated two physical drivers and examined the responses of a predator and prey and their interaction. The two drivers tested are fundamental in intertidal systems: air and water temperatures. The two species were the intertidal dogwhelk, Nucella ostrina, and its barnacle prey, Balanus glandula. My objective was to test alternative hypotheses that air and water warming have additive vs. non-additive effects on the whelk-barnacle interaction. Using a 14 day mesocosm experiment, I subjected animals to one of four temperature treatments—ambient (no temperature manipulation; water 12°C, air 13°C), warm water (15°C), warm air (27°C), or combined (water 15°C, air 27°C)—and measured the responses of N. ostrina, B. glandula, and their interaction strength.
Results/Conclusions
There were two key findings. First, air and water warming non-additively affected species interaction strength: warm water mitigated a 35% decrease in whelk feeding rate caused by warm air. Second, air warming had contrasting effects on individual growth rates of predator and prey. While whelk growth decreased by ~60% in warm air, barnacle growth increased by 47%. These findings suggest that combined warming will benefit barnacle populations more than their whelk predators. This study highlights the value of integrating species performances and interactions to understand how multiple physical drivers affect community structure.
Results/Conclusions
There were two key findings. First, air and water warming non-additively affected species interaction strength: warm water mitigated a 35% decrease in whelk feeding rate caused by warm air. Second, air warming had contrasting effects on predator and prey. While whelk growth decreased by ~60% in warm air, barnacle growth increased by 47%. These findings suggest that combined warming will benefit barnacle populations more than their whelk predators. This study highlights the value of integrating species performances and interactions to understand how multiple physical drivers affect community structure.