5.1a Communities and Ecosystems

Data-based question: fishing down marine food webs 

1. We can check what is in the stomach of the fish to determine what trophic levels it has consumed therefore, determining what trophic level the fish is in.

2a. Over the years, both the fresh water fish and marine fish have decreased trophic levels. However, the marine fish have a more constant decrease where has the fresh water fish have a faster rate of decline.


3. Increasing the age means that the size increases as well, which would mean that the range of prey would increase as well.

4. If the trophic level is lowered, the age is lowered as well. This is because they are related to each other.





One thought on “5.1a Communities and Ecosystems

  1. cafergy says:

    Grade 4 A good general understanding of the required knowledge and skills, and the ability to apply them effectively in normal situations. There is occasional evidence of the skills of analysis, synthesis and evaluation.

    Data-based questions: fishing down marine
    food webs
    page 180
    1 Check its stomach contents; determine trophic level
    of organisms within the stomach.
    2 a Both have been declining over the study
    period; rate of decline is faster in fresh water
    populations; rate of decline is more constant in
    marine/accelerating in freshwater.
    b Freshwater fisheries are more established/
    have been overfished for longer; freshwater
    populations smaller/more susceptible to
    3 Increasing age means increasing size; increasing
    size means broader range of prey including larger
    fish/higher trophic level fish.
    4 Age correlated with trophic level; lowering of
    trophic level means lowering of mean age.
    5 Greater biomass of lower trophic level means
    higher sustainable yield which allows higher
    trophic levels to recover.

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