---
id:"kb-2026-00456"
title:"Coral Reefs"
schema_type:"TechArticle"
category:"science"
language:"en"
confidence:"high"
last_verified:"2026-05-22"
generation_method:"ai_assisted"
ai_models:["claude-opus"]
derived_from_human_seed:true
primary_sources:
  - title:"The Biology of Coral Reefs (Sheppard, Davy, Pilling, 2nd Ed)"
    type:"book"
    year:2017
    url:"https://global.oup.com/academic/product/the-biology-of-coral-reefs-9780198787358"
    institution:"Oxford University Press"
secondary_sources:
  - title: "MDN Web Docs — HTTP"
    type: "documentation"
    year: 2026
    url: "https://developer.mozilla.org/en-US/docs/Web/HTTP"
    institution: "Mozilla"
completeness: 0.88
ai_citations:
  last_citation_check:"2026-05-22"
---

## TL;DR

Coral reefs are underwater ecosystems built by calcium carbonate skeletons of coral polyps — tiny animals with symbiotic algae (zooxanthellae). Cover <0.1% of ocean floor but host 25% of marine species. Great Barrier Reef (2,300 km, Australia) is the largest living structure on Earth. Bleaching: corals expel algae under heat stress → turn white → die.

## Core Explanation

Coral bleaching: triggered by 1-2°C above normal summer temperatures. Recovery possible if stress is brief. Threats: climate change (ocean warming + acidification), overfishing, pollution, coastal development. Acidification: CO₂ dissolves in ocean → carbonic acid → dissolves coral skeletons. Great Barrier Reef: 50% coral loss since 1995. Restoration: coral gardening, assisted evolution, marine protected areas.

## Further Reading

- [The Biology of Coral Reefs (Sheppard, Davy, Pilling, 2nd Ed)](https://global.oup.com/academic/product/the-biology-of-coral-reefs-9780198787358)