Global warming confers performance advantages to a non-native predator

Abstract

Anthropogenic impacts manifest in rising temperatures worldwide, with drastic consequences for communities and ecosystems. Ectotherms tend to reach a smaller size at maturity in warmer environments, however, whether these responses elicit performance advantages between native and invasive species remains poorly understood. This is of particular importance for aquatic ecosystems, where size structuring across trophic levels is profound, and effects of environmental change are exacerbated. Here, we investigated size-specific responses of aquatic predators (invasive racer goby, Babka gymnotrachelus; native European bullhead, Cottus gobio) to current and predicted future temperatures (15oC; 23oC), using a comparative functional response approach. We show that the growth rate of both predators was negatively affected by a temperature increase, but was consistently higher for the invasive species compared to the native. Specifically, at an increased temperature, all individuals of the native species lost body mass, while small individuals of the invader were still able to grow. This was driven by changes in predators’ foraging efficiency, increased in the invasive, and decreased in the native species. Fish foraging was also shaped by prey motility, with active prey consumed more often than inactive ones. The results indicate that a temperature increase may shift the competitive balance between invasive and native species, with the former being more robust to temperature increase under a limited food supply than native comparators. This could further modify the impact of invaders on the local communities, with implications for ecosystem stability.