SS1.07 Ecological Links to Population Dynamics and Productivity of Salmon
Date: Friday, June 14, 2002
Time: 9:15:00 AM
Location: Lecture Theatre
WipfliMS, Pacific Northwest Research Station, Wenatchee, USA,
Hudson, J, P, Pacific Northwest Research Station, Juneau, USA,
Caouette, J, P, USDA Forest Service, Juneau, USA,
Chaloner, D, T, University of Notre Dame, Notre Dame, USA,
Heintz, R, A, National Marine Fisheries Service, Juneau, USA,
Ecological effects of returning salmon on freshwater food webs
Pacific salmon (Oncorhynchus spp.) adults accumulate nutrients and energy in the ocean and deliver massive amounts to freshwater ecosystems along the north Pacific Rim when they return to their natal habitats to spawn. While some studies have shown that this biomass influx becomes incorporated into terrestrial and freshwater food webs, the full ecological implications of this subsidy remain unknown. Results of our research in southeast and southcentral Alaska have shown that these marine resource subsidies can have strong ecological effects on multiple trophic levels. Densities, biomass, growth rates, lipid reserves, and marine isotopes of nitrogen and carbon generally increased (from 2 to 20 times) in most food web components we sampled (biofilm, invertebrates, resident and juvenile anadromous fishes) in response to enrichment with salmon carcasses and eggs. Furthermore, higher salmon carcass densities resulted in increased responses in some food web components. These data suggest that salmon fuel a natural positive feedback that helps sustain their own populations and supports other species.