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Food Webs

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Food Webs information and PDF Files

  • 1. Aquatic Terrestrial Food Webs

    2. Carcass Food Web Nutrients
    Nutrient Input to Watersheds from Anadromous Fish Returns

    • Oligotrophic rivers like the Skagit River receive valuable Nitrogen and Phosphorus from salmon carcasses in coastal rivers.
    • Marine derived nutrients (pathways).
    • Important for biological productivity and biological diversity within the watershed.
    • Carcasses affect all trophic layers in the food web.

    Body biomass and nitrogen and phosphorus imports in metric tons to selected freshwater catchments within the Puget Sound Basin from recent peak wild spawning salmon escapements.

    (metric tons)

    Body Biomass

       

    Watershed Unit Name

    Totals

    Nitrogen

    Phosphorus

    Nooksack

    648

    19.7

    2.3

    Skagit

    1,164

    35.4

    4.2

    Stillaguamish

    512

    15.6

    1.8

    Puget Sound Total

    6,227

    189.3

    22.4

    Source: Cederholm et al. Pacific salmon and wildlife; ecological contexts, relationships, and implications for management.  Special Edition Technical Report, Washington Department of Fish and Wildlife, Olympia.

  • 3. Estuary Food Web
  • 4. Forest Stream Food Web

    In an undisturbed stream the majority of the energy input is allochthonous (CPOM). Shredders and collectors around the CPOM/FPOM processing dominate the food web. Light is a minor energy input from gaps in the canopy.

    When the riparian zone is removed the food web is reduced to a simple producer/grazer system. If eutrophication is added the food web is further simplified.

    Macroinvertebrates Tolerance Groups to Eutrophication

    Group I; Pollution Intolerant, Sensitive to Pollution

    • Trichoptera (caddis fly)
    • Megaloptera, Corydalus (hellgrammites)
    • Ephemeoptera (mayfly)
    • Gastropoda (gilled snails)
    • Coleoptera, Elmidae (riffle beetles)
    • Plecoptera (stonefly)

    Group II; Somewhat Pollution Tolerant

    • Coleoptera (other beetles)
    • Pelecypoda (clams and mussels)
    • Pisididae (fingernail clams)
    • Turbillaria (flatworms or planaria)
    • Diptera, Tupulidae (Cranefly)
    • Crustacea (crayfish, scud, sowbug)
    • Hemiptera (water boatman, backswimmer, toe biter, water strider)
    • Odonata (dragonfly, damselfly)
    • Megaloptera, Chauliodes & Sialidae (fishfly, alderfly)

    Group III; Pollution Tolerance High

    • Oligocheta (worms)
    • Diptera, Simulidae (blackfly)
    • Hirudinea (leech)
    • Diptera, Chironomide (midge, bloodworm)
    • Gastropoda (other snails)
  • 5. Rhithron Food Web
  • 6. Potamon Food Web