IB Environmental Systems Revision

Water & Aquatic Systems

The water cycle, aquatic food production systems and water pollution.

Water & Aquatic Systems is a core part of IB Environmental Systems. Revise the key concepts and common mistakes below, then lock them in with the free games.

Key concepts

Hydrological cycleEvaporation, transpiration, condensation, precipitation, runoff, infiltration, groundwater flow.
AquiferPermeable rock storing groundwater; recharged by infiltration; over-abstraction lowers water table.
Maximum sustainable yieldHighest catch that can be removed indefinitely; theoretically half of carrying capacity (Schaefer 1954).
EutrophicationNutrient enrichment causes algal blooms, decomposition, hypoxia; collapse of aquatic ecosystem.
AquacultureFarmed fish/shellfish; ~50% of fish consumed (FAO 2020); concerns about effluent and disease.
Cod collapseNewfoundland Grand Banks cod fishery collapsed 1992; moratorium imposed; lesson in overfishing.

Common mistakes to avoid

Questions where students often pick the tempting wrong answer — make sure you know the right one:

Is energy recycled within an ecosystem?✗ Yes, energy cycles round endlessly.   ✓ No — energy flows through and is lost as heat; nutrients are recycled.
What does biodiversity measure?✗ Only the number of animals.   ✓ The variety of all living things and their genes in an area.

Practise Water & Aquatic Systems — free games

Test yourself with these quick revision games for this topic:

▶ Two Truths, One Lie▶ Reveal Race▶ Connections Grid▶ Falling Words▶ Word Web

See all 17 games in the Subjects Arcade →

More IB Environmental Systems topics

Foundations of Environmental SystemsEcosystems & BiodiversityAtmospheric SystemsClimate Change & EnergySoil & Terrestrial SystemsHuman Systems & Resource UseEthics, Law & Economics

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