, Volume 144, Issue 4, pp 558–569

Marine-derived nitrogen and carbon in freshwater-riparian food webs of the Copper River Delta, southcentral Alaska

  • Brendan J. Hicks
  • Mark S. Wipfli
  • Dirk W. Lang
  • Maria E. Lang
Stable Isotopes Issue

DOI: 10.1007/s00442-005-0035-2

Cite this article as:
Hicks, B.J., Wipfli, M.S., Lang, D.W. et al. Oecologia (2005) 144: 558. doi:10.1007/s00442-005-0035-2


After rearing to adulthood at sea, coho salmon (Oncorhynchus kisutch) return to freshwater to spawn once and then die on or near their spawning grounds. We tested the hypothesis that spawning coho salmon return marine N and C to beaver (Castor canadensis) ponds of the Copper River Delta (CRD), Cordova, southcentral Alaska, thereby enhancing productivity of the aquatic food webs that support juvenile coho salmon. We sampled three types of pond treatment: (1) natural enrichment by spawning salmon, (2) artificial enrichment via addition of salmon carcasses and eggs, and (3) ponds with no salmon enrichment. All ponds supported juvenile coho salmon. Seasonal samples of stable isotopes revealed that juvenile coho salmon, threespine sticklebacks (Gasterosteus aculeatus), caddisfly larvae, leeches, and chironomid midge larvae were enriched with marine N and C. The aquatic vascular plants bur reed (Sparganium hyperboreum), pondweed (Potamogeton gramineus), and mare’s tail (Hippuris vulgaris) were enriched with marine N only. Riparian vegetation (Sitka alder Alnus viridis ssp. sinuata and willow Salix spp.) did not show enrichment. Artificial additions of adult carcasses and eggs of coho salmon increased the δ15N and δ13C values of juvenile coho salmon. In this dynamic and hydrologically complex coastal environment, spawning coho salmon contributed marine N and C comprising 10–50% of the dietary needs of juvenile coho salmon through direct consumption of eggs and carcass material. Invertebrates that have assimilated marine N and C yield a further indirect contribution. This perennial subsidy maintains the productivity of the ecosystem of the coho salmon on the CRD.


Stable isotopesMarine nutrientsDietary analysisCoho salmonAquatic invertebrates

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Brendan J. Hicks
    • 1
  • Mark S. Wipfli
    • 2
  • Dirk W. Lang
    • 3
  • Maria E. Lang
    • 4
  1. 1.Centre for Biodiversity and Ecology Research, Department of Biological SciencesThe University of WaikatoHamiltonNew Zealand
  2. 2.USGS, Alaska Cooperative Fish and Wildlife Research Unit, Institute of Arctic BiologyUniversity of Alaska FairbanksFairbanksUSA
  3. 3.Cordova Ranger DistrictUSDA Forest ServiceCordovaUSA
  4. 4.School of Fisheries and Ocean SciencesUniversity of Alaska Fairbanks—Juneau CenterJuneauUSA