The energetic contributions of aquatic primary producers to terrestrial food webs in a mid-size river system

Adam Kautza, S. Mažeika, P. Sullivan

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Rivers are increasingly recognized as providing nutritional subsidies (i.e., energy and nutrients) to adjacent terrestrial food webs via depredation of aquatic organisms (e.g., emergent aquatic insects, crayfish, fish) by terrestrial consumers. However, because these prey organisms assimilate energy from both aquatic (e.g., benthic algae, phytoplankton, aquatic macrophytes) and terrestrial (e.g., riparian leaf detritus) primary producers, river subsidies to terrestrial consumers represent a combination of aquatically and terrestrially derived energy. To date, the explicit contribution of energy derived from aquatic primary producers to terrestrial consumers has not been fully explored yet might be expected to be quantitatively important to terrestrial food webs. At 12 reaches along a 185-km segment of the sixth-order Scioto River system (Ohio, USA), we quantified the relative contribution of energy derived from aquatic primary producers to a suite of terrestrial riparian consumers that integrate the adjacent landscape across multiple spatial scales through their foraging activities (tetragnathid spiders, rove beetles, adult coenagrionid damselflies, riparian swallows, and raccoons). We used naturally abundant stable isotopes (13C and 15N) of periphyton, phytoplankton, macrophytes, and terrestrial vegetation to evaluate the energetic contribution of aquatic primary producers to terrestrial food webs. Shoreline tetragnathid spiders were most reliant on aquatic primary producers (50%), followed by wider-ranging raccoons (48%), damselflies (44%), and riparian swallows (41%). Of the primary producers, phytoplankton (19%) provisioned the greatest nutritional contribution to terrestrial consumers (considered collectively), followed by periphyton (14%) and macrophytes (11%). Our findings provide empirical evidence that aquatic primary producers of large streams and rivers can be a critical nutritional resource for terrestrial food webs. We also show that aquatically derived nutrition contributes to both shoreline and broader-ranging terrestrial consumers and thus may be an important landscape-scale energetic linkage between rivers and upland habitats.

Original languageEnglish (US)
Pages (from-to)694-705
Number of pages12
Issue number3
StatePublished - Mar 1 2016

Bibliographical note

Funding Information:
Research support was provided by state and federal funds appropriated to The Ohio State University, Ohio Agricultural Research and Development Center and by the Ohio Department of Natural Resources, Division of Wildlife through the USFWS State Wildlife Grant Program and the Ohio Biodiversity Conservation Partnership (SMPS). We thank J. Alberts, P. Tagwireyi, M. Berzins, L. Boaz, D. Vent, A. Dorobek, and K. Diesburg for their help in the field and laboratory, and K. Hossler, J. Bauer, K. Jaeger, and two anonymous reviewers for their reviews of earlier manuscript drafts. We would also like to acknowledge B. Wolfe, A. Steinagel, and I. Plourde for their assistance with raccoon sampling.

Publisher Copyright:
© 2016 by the Ecological Society of America.


  • Aquatically derived energy
  • Food web
  • Mid-size river
  • Ohio
  • Phytoplankton
  • Riparian
  • Scioto River
  • Terrestrial consumers
  • USA


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