Isotopic evidence of trophic links of terrestrial and aquatic food webs in Oksky Nature Reserve
Emergent aquatic insects transport nutrients from aquatic to terrestrial ecosystems and can serve as an important energy source for litter- and soil-dwelling generalist predators in riparian habitats. We studied the isotopic composition of soil animals in a dry pine-dominated forest and two riparian forests. The natural difference in the isotopic composition of carbon (13C/12C) of aquatic (δ13C ca. -33‰) and terrestrial (δ13C larger than -27‰) invertebrates was used to estimate the contribution of aquatic carbon in the tissues of soil animals in an oak-dominated and birch-dominated riparian habitats. Litter-dwelling generalist predators were the main acceptors of the aquatic subsidy. The proportion of the aquatic carbon differed strongly among predator species, but in general it was larger in ground beetles than in wolfspiders. This was likely due to the dominance of hygrophilous Carabidae species in the riparian habitats.