Seawater carbonate chemistry, physiological performance of Semibalanus balanoides and Nucella lapillus, and their predator-prey dynamics.

While there is increasing evidence for the impacts of climate change at the individual level, much less is known about how species' likely idiosyncratic responses may alter ecological interactions. Here, we demonstrate that ocean acidification and warming not only directly alter species' (individual) physiological performance, but also their predator-prey dynamics. Our results demonstrate that tissue production (used as a proxy for prey quality) in the barnacle Semibalanus balanoides was reduced under scenarios of future climate change, and hence their ability to support energy acquisition for dogwhelk Nucella lapillus through food provision was diminished. However, rather than increasing their feeding rates as a compensatory mechanism, consumption rates of N. lapillus were reduced to the point that they exhibited starvation (a loss of somatic tissue), despite prey resources remaining abundant. The resilience of any marine organism to stressors is fundamentally linked to their ability to obtain and assimilate energy. Therefore, our findings suggest that the cost of living under future climate change may surpass the energy intake from consumption rates, which is likely exacerbated through the bottom-up effects of reduced prey quality. If, as our results suggest, changes in trophic transfer of energy are more common in a warmer, high CO2 world, such alterations to the predator-prey dynamic may have negative consequences for the acquisition of energy in the predator and result in energetic trade-offs. Given the importance of predator-prey interactions in structuring marine communities, future climate change is likely to have major consequences for community composition and the structure and function of ecosystems.