Data from: Invasion-mediated effects on marine trophic interactions in a changing climate: positive feedbacks favour kelp persistence

The interactive effects of ocean warming and invasive species are complex
and remain a source of uncertainty for projecting future ecological
change. Climate-mediated change to trophic interactions can have pervasive
ecological consequences, but the role of invasion in mediating trophic
effects is largely unstudied. Using manipulative experiments in replicated
outdoor mesocosms, we reveal how near-future ocean warming and macrophyte
invasion scenarios interactively impact gastropod grazing intensity and
preference for consumption of foundation macroalgae (Ecklonia radiata and
Sargassum vestitum). Elevated water temperature increased consumption of
both macroalgae through greater grazing intensity. Given the documented
decline of kelp (E. radiata) growth at higher water temperatures, enhanced
grazing could contribute to the shift from kelp-dominated to
Sargasssum-dominated reefs that is occurring at the low-latitude margins
of kelp distribution. However, presence of a native invader (Caulerpa
filiformis) was related to low consumption by the herbivores on dominant
kelp at warmer temperatures. Thus, antagonistic effects between climate
change and a range expanding species can favour kelp persistence in a
warmer future. Introduction of species should, therefore, not
automatically be considered unfavourable under climate change scenarios.
Climatic changes are increasing the need for effective management actions
to address the interactive effects of multiple stressors and their
ecological consequences, rather than single threats in isolation.