Fish and trophic webs

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  • Created by: hanRose
  • Created on: 01-01-22 17:28
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  • predator- prey selectivity
    • mouth size/ structure affect prey capacity  coefficient
    • behaviour (foraging tactics): fish select prey size to minimise different energy expenditure of capture/handling time (larger prey more costly
    • Fish and trophic webs (L7)
      • trophic guilds
        • groups of fish - similar diet and feeding methods + similar niches/ resources
        • strong evidence - resource partitioning in diverse tropical  communities than in temperate streams
        • concept - change in food/ flexibility in food. preference over seasons life stage: reflect complex food webs
          • identify  functional routes
          • web analysis + classify fish communities
        • categories
          • piscivore
          • benthic invert feeders i
          • surface/ water column
          • generalised invert
          • plankivore
          • herbivore/  detritivore
          • omnivore
          • parasite
      • marine subsidy pathway of anadromous salmonids
        • pacific salmon spewing stocks huge/ semelparous = carcasses/ deposited eggs
        • important vector of nutrients (C/N/P) from sea to terrestrial/ aquatic in nutrient poor North pacific river
        • ^13C/^12C / ^^15N/  ^14N ratio (heavier isotopes are marine origins) used to trace pathways of marine derived nutrient (MDN) in freshwater/ terrestrial ecosystem
        • >60% invert N est from salmon- coastal Alaskan bear 94% C/N from salmon: carcasses up to 5km from river
        • current/ historical salmon biomass
          • biomass: historical : 156,000-254,298 current: 11,843 -13,747
          • nitrogen historical: 4,853 - 6,854 current: 360 - 418
          • phosphate historical 574 - 810 current 43 - 9
        • loss salmon stocks (may fix naturally low nutrient status systems in low productive state - unless artificially restored
        • European Atlantic salmon sea trout - similar P/N subsidy effect = but much smaller scale

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