title: Terrestrial support of lake food webs: Synthesis reveals controls over cross-ecosystem resource use.
abstract: Widespread evidence that organic matter exported from terrestrial into aquatic ecosystems supports recipient food webs remains controversial. A pressing question is not only whether high terrestrial support is possible but also what the general conditions are under which it arises. We assemble the largest data set, to date, of the isotopic composition (δ2H, δ13C, and δ15N) of lake zooplankton and the resources at the base of their associated food webs. In total, our data set spans 559 observations across 147 lakes from the boreal to subtropics. By predicting terrestrial resource support from within-lake and catchment-level characteristics, we found that half of all consumer observations that is, the median were composed of at least 42% terrestrially derived material. In general, terrestrial support of zooplankton was greatest in lakes with large physical and hydrological connections to catchments that were rich in aboveground and belowground organic matter. However, some consumers responded less strongly to terrestrial resources where within-lake production was elevated. Our study shows that multiple mechanisms drive widespread cross-ecosystem support of aquatic consumers across Northern Hemisphere lakes and suggests that changes in terrestrial landscapes will influence ecosystem processes well beyond their boundaries.
authors.affiliation: Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, U.K.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Tanentzap
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Brian W
authors.identifier: 0000-0003-1105-4971
authors.initials: BW
authors.lastname: Kielstra
authors.affiliation: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA.
authors.forename: Grace M
authors.initials: GM
authors.lastname: Wilkinson
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, S-223 62 Lund, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Berggren
authors.affiliation: Department of Natural Resource Sciences, McGill University, Sainte Anne de Bellevue, Quebec H9X 3V9, Canada.
authors.forename: Nicola
authors.identifier: 0000-0003-4815-8301
authors.initials: N
authors.lastname: Craig
authors.affiliation: Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Quebec H3C 3P8, Canada.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Del Giorgio
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, U.K.; The Wild Trout Trust, PO Box 120, Waterlooville PO8 0WZ, U.K.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Grey
authors.affiliation: Vale Living with Lakes Centre, Laurentian University, Sudbury, Ontario P3E 2C6, Canada.
authors.forename: John M
authors.initials: JM
authors.lastname: Gunn
authors.affiliation: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
authors.forename: Stuart E
authors.initials: SE
authors.lastname: Jones
authors.affiliation: Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 90187 Umeå, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Karlsson
authors.affiliation: Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA.
authors.forename: Christopher T
authors.identifier: 0000-0002-2850-4257
authors.initials: CT
authors.lastname: Solomon
authors.affiliation: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA.
authors.forename: Michael L
authors.identifier: 0000-0001-5945-6131
authors.initials: ML
authors.lastname: Pace
mesh_terms: D020387:Food Chain; D060106:Lakes; D008954:Models, Biological
keywords: allochthony; food webs; land-water linkages; organic carbon