Range-extending tropical herbivores increase diversity, intensity and extent of herbivory functions in temperate marine ecosystems

1. Climate change is modifying species distributions around the world, forcing some species poleward, where they can alter trophic interactions. Many tropical herbivorous fishes have successfully expanded their ranges into temperate ecosystems, and while it is clear they drive increases in herbivory rates in specific localities, little is known about how they might affect the diversity of herbivory functions across large spatial scales, considering their interaction with assemblages of native herbivores in temperate habitats.
2. We assessed the spatial overlap and habitat associations of native temperate and range-expanding tropical herbivorous fishes in six sub-regions of south-western Australia to determine how incursions of tropical species may have affected the diversity, redundancy (index of uniqueness) and the ‘spatial extent’ (addition of functions in new areas) and ‘intensity’ (increasing density of functional groups) of specific herbivory functions in recipient ecosystems.
3. T...