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Threats to oceans
I can explain the main threats to oceans and how they affect marine environments.
Lesson 6 of 14
New
New
- Year 9
Threats to oceans
I can explain the main threats to oceans and how they affect marine environments.
Lesson details
Key learning points
- Plastic pollution harms marine life and spreads through ocean currents.
- Overfishing reduces fish populations and disrupts marine food chains.
- Climate change warms oceans and causes coral bleaching.
- Oil spills and chemical pollution damage marine ecosystems.
- Rising sea levels and acidification threaten coastal and ocean habitats.
Keywords
Ocean current - continuous movements of seawater in the ocean
Overfishing - catching too many fish, so the breeding population becomes too depleted to recover
Food chain - a sequence that shows how a group of living things are linked by what they eat
Ocean acidification - when the ocean becomes more acidic because it absorbs too much CO₂ from the air
Common misconception
Ocean acidification is when water is polluted from human activities on land.
Ocean acidification is when the ocean absorbs extra carbon dioxide (CO₂) from the air, which makes the water more acidic.
Ask students to do some extra research on the 1996 Milford Haven Oil spill, looking at the causes and effects.
Teacher tip
Equipment
Licence
This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What does the term 'Anthropocene' describe?
What does the term 'Anthropocene' describe?
A period when dinosaurs existed
A future time of total environmental balance
A scientific term for volcanic activity
Q2.Which of these is a human activity that directly contributes to climate change?
Which of these is a human activity that directly contributes to climate change?
Planting trees
Walking instead of driving
Using solar panels
Q3.What is a consequence of overfishing?
What is a consequence of overfishing?
Cleaner oceans
Balanced marine food webs
Increased fish biodiversity
Q4.Deforestation often reduces and increases CO₂ levels.
Deforestation often reduces and increases CO₂ levels.
Q5.What does your carbon footprint measure?
What does your carbon footprint measure?
How far you walk each day
The size of your shoe
Your impact on wildlife
Q6.Which of these is a sustainable action?
Which of these is a sustainable action?
Buying fast fashion
Eating imported food only
Leaving lights on all day
Assessment exit quiz
4 Questions
Q1.Match the keywords to their definitions:
Match the keywords to their definitions:
Q2.What causes ocean acidification?
What causes ocean acidification?
Oil spills in the sea
Chemicals from farming washing into the sea
Plastic pollution in the water
Q3.A student says, "Ocean acidification is caused by pollution from land." What’s a better explanation?
A student says, "Ocean acidification is caused by pollution from land." What’s a better explanation?
It’s caused by water mixing with plastic
It happens when oil spills enter the sea
It’s due to farm chemicals washing into the sea
Q4.What might happen if smaller fish are removed from a food chain?
What might happen if smaller fish are removed from a food chain?
Larger fish increase in number
Nothing changes
Coral reefs grow faster
