C3  Impacts of Humans on Ecosystems

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Essential Idea:

Human activities impact

on ecosystem function


  • Introduced alien species can escape into local ecosystems and become invasive
  • Competitive exclusion and the absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive
  • Pollutants become concentrated in the tissues of organisms at higher trophic levels by biomagnification
  • Macroplastic and microplastic debris has accumulated in marine environments


  • Study of the introduction of cane toads in Australia and one other local example of the introduction of an alien species
  • Discussion of the trade-off between control of the malarial parasite and DDT pollution
  • Case study of the impact of marine plastic debris on Laysan albatrosses and one other named example


  • Analysis of data illustrating the causes and consequences of biomagnification
  • Evaluation of eradication programmes and biological control as measures to reduce the impact of alien species