Explain how marine pollution caused by an oil spill can lead to a reduction in biodiversity in an affected coastal habitat.

Cambridge International IGCSE Biology (0610) — 20.2 Habitat destruction · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Oil coats or suffocates organisms such as seabirds, fish and invertebrates, killing them directly.
Loss of these species breaks food chains and food webs, so predators and prey are affected.
Oil blocks light from reaching underwater plants, stopping photosynthesis and causing the plants to die.
The death of many species reduces the number of different species present, lowering biodiversity.

Examiner tips

  • Use the word ‘oil’ and ‘biodiversity’ early. Show the chain: oil → organism death → food web disruption → plant death → fewer species. Keep sentences short and factual.
  • common_mistakes
  • :
  • Confusing oil spill with other pollutants. Failing to mention light/ photosynthesis. Using vague terms like ‘damage’ instead of specific effects.

Mark scheme (4 marks)

  1. Oil coats or suffocates/kills organisms directly (e.g. seabirds, fish, marine invertebrates)
  2. Loss of one species disrupts food chains / food webs in the habitat
  3. Oil prevents light reaching underwater plants / prevents photosynthesis, causing plants to die
  4. Death of multiple species / reduction in number of different species = reduction in biodiversity

Key terms in this question

marine pollution · biodiversity

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