PRIMARY RESEARCH PAPER Differential responses of aquatic consumers to variations in leaf-litter inputs Michael J. Rubbo Æ Lisa K. Belden Æ Joseph M. Kiesecker Received: 22 August 2007 / Revised: 10 January 2008 / Accepted: 16 January 2008 Ó Springer Science+Business Media B.V. 2008 Abstract Terrestrial support of aquatic food webs is becoming well established in the science of ecology. However, while terrestrial subsidies of energy have been shown to exert strong effects on aquatic food webs, it is less clear how variations in these subsidies, via natural or anthropogenic factors, will affect recipient ecosystems. To assess the influence of variations in terrestrial subsidies on an aquatic food web, we manipulated leaf-litter inputs in artificial ponds. Decreasing litter inputs did not affect any of the response variables in artificial ponds. This may be because the minimal amount of terrestrial carbon present combined with autochthonous pro- duction was enough to sustain the food web and/or the food web was altered in ways not detected by the experimental design. However, increasing leaf-litter inputs increased the percent survival and develop- mental rate of larval wood frogs (Rana sylvatica). Conversely, increasing litter input appeared to have no influence on zooplankton or salamander larvae. Increasing litter inputs also increased the dissolved organic carbon content and decreased the percent saturation of dissolved oxygen in artificial ponds. As system respiration in aquatic systems is frequently dominated by microbial respiration, we hypothesize that the effects of increasing litter input on wood frogs were the result of an increase food resources (i.e., microbes) for tadpoles. The lack of a response by salamander larvae and zooplankton may be due to the densities of zooplankton in tanks providing enough food for salamanders in all treatments, variation among specific zooplankton species in their ability to exploit these resources and transfer energy to salamanders, or omnivory among zooplankton offset- ting the affects of leaf-litter inputs. Additional work is needed to determine the influence of litter inputs on zooplankton and salamanders in this community. These data demonstrate that variations in leaf-litter inputs can influence food web structure; however, the importance of these variations will likely be dependent upon the trophic position of various consumers. Keywords Allochthonous Á Amphibian Á Food web Á Leaf-litter Á Microbial Á Carbon Handling editor: J. Cole M. J. Rubbo Á L. K. Belden Á J. M. Kiesecker Department of Biology, Pennsylvania State University, 208 Mueller Laboratory, University Park, PA 16801, USA M. J. Rubbo (&) Teatown Lake Reservation, 1600 Spring Valley Rd, Ossining, NY 10562, USA e-mail: mrubbo@teatown.org L. K. Belden Department of Biology, Virginia Polytechnic Institute and State University, 2125 Derring Hall, Blacksburg, VA 24061, USA J. M. Kiesecker The Nature Conservancy, Wyoming Field Office, 258 Main Street, Suite 200, Lander, WY 82520, USA 123 Hydrobiologia DOI 10.1007/s10750-008-9298-z