Tropical and temperate differences in the trophic structure and aquatic prey use of riparian predators

The influence of aquatic resource-inputs on terrestrial communities is
poorly understood, particularly in the tropics. We used stable isotope
analysis of carbon and nitrogen to trace aquatic prey use and quantify
impact on trophic structure in 240 riparian arthropod communities in
tropical and temperate forests. Riparian predators consumed more aquatic
prey and were more trophically diverse in the tropics than temperate
regions, indicating tropical riparian communities are both more reliant
on, and impacted by, aquatic resources than temperate communities. This
suggests they are more vulnerable to disruption of aquatic-terrestrial
linkages. Although aquatic resource use declined strongly with distance
from water, we observed no correlated change in trophic structure,
suggesting trophic flexibility to changing resource availability within
riparian predator communities in both tropical and temperate regions. Our
findings highlight the importance of aquatic resources for riparian
communities, especially in the tropics, but suggest distance from water is
less important than resource diversity in maintaining terrestrial trophic
structure.