IELTS Reading 練習珊瑚礁生態系（含題目+詳解）

Coral Reef Ecosystems

IELTS · 雅思備考 · 12 min read · 2026-04-25

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主題: Coral reefs, bleaching and conservation
文章重點: Coral reefs depend on a partnership between corals and algae that breaks down under heat stress; saving the reefs ultimately requires global emissions cuts, not only local restoration.
難度: 中等偏難 · Upper Intermediate
建議時間: 18 分鐘

重要單字

shelter — to provide protection or housing / 提供庇護
zooxanthellae — single-celled algae living inside corals / 蟲黃藻
photosynthesise — to use sunlight to make food / 行光合作用
tolerances — the limits within which something can survive / 容忍範圍
bleaching — corals turning white after losing their algae / 白化
acidification — the process of becoming more acidic / 酸化

30 秒快速理解 30-second summary

Coral reefs cover less than one per cent of the ocean floor but house a quarter of all marine species, thanks to a partnership between corals and tiny algae called zooxanthellae. Heat stress causes corals to expel their algae and bleach. Bleaching, agricultural runoff, overfishing and ocean acidification have all increased since the 1980s. Local restoration helps, but biologists agree only rapid emissions cuts can save the reefs long term.

逐段練習 Read paragraph by paragraph

1 段落 1 — A partnership of two species

Although coral reefs cover less than one per cent of the ocean floor, they shelter roughly a quarter of all known marine species. This extraordinary density of life is built on a partnership between two very different organisms. The corals themselves are tiny animals that secrete the limestone cups in which they live. Inside their soft tissue are millions of single-celled algae called zooxanthellae. These algae photosynthesise like plants and pass most of the sugars they make to the corals, which in return supply shelter and waste nutrients.

本段重要單字 (3)

shelter — to provide protection or housing / 提供庇護
zooxanthellae — single-celled algae inside corals / 蟲黃藻
photosynthesise — to use sunlight to make food / 行光合作用

Quick Check · 隨堂小測

What does each partner contribute in the coral-algae relationship?

The algae give shelter; the corals give sugar.
The algae give sugar from photosynthesis; the corals give shelter and waste nutrients.
Both give only sugar to each other.

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答案：B — The algae give sugar from photosynthesis; the corals give shelter and waste nutrients.

The paragraph says the algae photosynthesise and pass sugars to the corals, while the corals "supply shelter and waste nutrients" in return.

2 段落 2 — Narrow tolerances and bleaching

The arrangement is so productive that reefs flourish in clear, nutrient-poor tropical waters where little else grows. Reef-building corals, however, have narrow tolerances. They thrive only in seawater between roughly 23 C and 29 C, in salinity close to that of the open ocean and at depths shallow enough for sunlight to reach the algae. When sea temperatures rise even one or two degrees above the local norm for several weeks, the corals expel their algae in a stress response known as bleaching. Without their photosynthetic partners, the corals turn white and may die.

本段重要單字 (3)

tolerances — the limits within which something can survive / 容忍範圍
salinity — the salt content of water / 鹽度
bleaching — corals turning white after losing algae / 白化

Quick Check · 隨堂小測

What happens during a coral bleaching event?

Corals consume the algae living inside them.
Corals expel their algae as a stress response and turn white.
Corals grow extra algae to protect themselves from heat.

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答案：B — Corals expel their algae as a stress response and turn white.

The paragraph says the corals "expel their algae in a stress response known as bleaching" and then turn white. They do not consume or grow extra algae.

3 段落 3 — Compounding pressures

Mass bleaching events have become dramatically more frequent since the 1980s. The Great Barrier Reef, which lies along Australia's north-east coast and is the largest reef system on Earth, suffered five separate mass bleachings between 2016 and 2024. Other pressures compound the problem: agricultural runoff alters water chemistry, overfishing removes the herbivorous fish that keep algae in check, and ocean acidification — caused by the same carbon emissions that warm the water — dissolves the limestone faster than corals can replace it.

本段重要單字 (3)

compound — to make a problem worse by adding to it / 使惡化
runoff — water flowing off land into rivers and the sea / 逕流
acidification — the process of becoming more acidic / 酸化

Quick Check · 隨堂小測

Beyond rising temperatures, which pressures threaten reefs?

Only agricultural runoff.
Runoff, overfishing and ocean acidification together.
Tourist diving and shipwrecks only.

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答案：B — Runoff, overfishing and ocean acidification together.

The paragraph explicitly lists three compounding pressures: runoff, overfishing and ocean acidification.

4 段落 4 — Restoration vs global action

Restoration efforts include cultivating heat-tolerant coral varieties in coastal nurseries and replanting them onto damaged reef sections. Such projects have shown encouraging local results, but they cannot keep pace with the global scale of the threat. Most marine biologists now agree that the long-term survival of coral reefs as they currently exist depends on rapid reductions in greenhouse-gas emissions worldwide. Local nurseries can buy time and protect particular reefs, but they cannot replace global climate action.

本段重要單字 (3)

restoration — returning something to its earlier state / 復原、修復
nurseries — places where young plants or animals are grown / 育苗場
emissions — gases released into the atmosphere / 排放物

Quick Check · 隨堂小測

What does the writer suggest about local restoration projects?

They have failed completely.
They help locally but cannot match the global scale of the threat.
They have replaced the need to cut emissions.

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答案：B — They help locally but cannot match the global scale of the threat.

The paragraph says local results are "encouraging" but the projects "cannot keep pace with the global scale of the threat" — they help, but global emissions cuts are still essential.

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閱讀前先看 Before you read

30 秒快速理解 30-second summary

逐段練習 Read paragraph by paragraph

1 段落 1 — A partnership of two species

2 段落 2 — Narrow tolerances and bleaching

3 段落 3 — Compounding pressures

4 段落 4 — Restoration vs global action

每天 5 分鐘的系統練習

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