The living world · GCSE Geography
Coral reefs and the Maldives
GCSE Geography coral reefs: polyp biology, reef types, Maldives tourism and fishing economy, bleaching, sea-level rise, and marine protected area management.
Reefs are animal cities built on algae salaries — warm clear water pays; heat and acid bankrupt them.
The important bits
What you need to know
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Coral reefs are biodiverse marine ecosystems built by coral polyps — tiny animals with calcium carbonate skeletons. Most reef-building corals host zooxanthellae algae that photosynthesise and share sugars; the coral provides shelter.
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Conditions: shallow, clear, warm water (about 18–30°C, optimal ~26°C), low nutrients (clear water paradox — corals compete poorly with algae in murky rich water), sunlight for algae, stable salinity.
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Types: fringing reefs (along coast — Maldives), barrier reefs (lagoon between reef and land — Great Barrier), atolls (ring around submerged volcano — classic Maldives geometry).
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Maldives: Indian Ocean archipelago, average ground height ~1.5 m, population on scattered atolls, economy heavily tourism (resorts on uninhabited islands) and tuna fishing.
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Biodiversity: fish nurseries, molluscs, sharks, rays — high interdependence. Reefs protect coasts from wave energy; without them, island erosion accelerates.
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Threats: coral bleaching when sea temperature spikes (1998, 2016 El Niño events devastated Maldives reefs); ocean acidification dissolving skeletons; dynamite fishing (less now), anchor damage, sewage from resorts, plastic.
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Sea-level rise: islands built on coral platforms; some natural reef growth may keep pace locally, but stronger storms and bleaching undermine the system. “Sinking nation” headlines are climate justice geography.
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Management: marine protected areas, mooring buoys not anchors, sustainable tourism codes, coral nurseries and transplantation pilots, global mitigation (Maldives cannot cool the ocean alone).
Quotations worth analysing
Short evidence. Real method.
“Bleaching is the coral firing its algae roommate when the water gets too hot — white is stress, not decoration.”
Link to rising SST and El Niño. If polyps stay white too long, they starve and die.
“Maldives tourism needs healthy reefs; reefs need cooler oceans — a global-local loop.”
Local MPAs help; without global mitigation, adaptation is reef repair on a warming planet.
Go deeper
Why corals need clear, nutrient-poor water
Murky, fertilised water favours fast-growing algae and plankton that smother corals. Corals evolved in oligotrophic tropical seas where their algal partners win the light race. Sediment from coastal development blocks light; sewage adds nutrients. In exams, name the condition (clear, warm, shallow) and the partnership (polyp + zooxanthellae). A reef is biology plus chemistry plus water quality — not “pretty rocks”.
Go deeper
Maldives: development on a knife edge
Resort islands import labour, desalinate water, and generate waste; one broken sewage pipe can bleach a house reef. Tourism dollars fund MPAs and coral gardening, but also flights that emit CO₂. Tuna fishing is more sustainable when pole-and-line, but fleets follow stocks across EEZs. A 9-mark answer moves from reef ecology to economy to climate threat, then names management (buoys, no-touch diving rules, Paris mitigation advocacy). The Maldives government has literally held underwater cabinet meetings for publicity — use as media hook, then analyse real policy limits.
See the idea in action
Question: explain threats to coral reefs using a named place. Place: Maldives. Threat 1: bleaching from rising sea temperatures (2016 event) — algae expelled, polyps die, tourism and fisheries suffer. Threat 2: sea-level rise and storm surge on low islands. Management: marine reserves, coral nurseries, sustainable tourism; global emission cuts essential. Judgement: local care cannot outrun a warming ocean.
Exam technique
Turn knowledge into marks
Always explain the coral–algae partnership. Maldives names tourism, height above sea, and bleaching in one case study — do not swap in Great Barrier unless asked.
Common mistakes
Do not give these marks away
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Calling corals plants or rocks only — they are animals.
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Describing bleaching with no heat mechanism.
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Ignoring economic dependence on reefs in Maldives answers.
What causes coral bleaching?
ACorals growing too quickly in cold water
BStress, often from high sea temperatures, causing polyps to expel zooxanthellae algae
CToo many fish eating the coral
DFreshwater from rivers making the sea less salty always helps corals
Show the answer
Stress, often from high sea temperatures, causing polyps to expel zooxanthellae algae. Without algae, corals lose colour and food supply. Prolonged bleaching kills reefs. Acidification and pollution add stress.
Quick questions
If this is the bit you searched
What is an atoll?
A ring-shaped coral reef and islands around a lagoon, often atop a submerged volcanic peak. The Maldives is an atoll nation.
Why are reefs important for coasts?
They dissipate wave energy, reducing erosion and storm damage — critical for low islands like the Maldives.
Can corals recover from bleaching?
Sometimes if stress ends quickly and algae return. Repeated or severe bleaching kills reefs and takes decades to rebuild.