Coral Reefs
CORAL REEFS are the rainforests of the sea. Despite covering less than 1% of the ocean, they support about 25% of all marine species. They're built by tiny coral animals (POLYPS) that secrete calcium carbonate skeletons. Over thousands of years, generations of corals build massive structures visible from space. The Great Barrier Reef in Australia is the largest, stretching 1,400 miles.
How corals live. Coral polyps live in symbiosis with TINY ALGAE called zooxanthellae. The algae do photosynthesis, sharing sugars with the coral. The coral provides shelter and CO2. Together, they thrive in clear, sunlit, warm shallow water. Without the algae, corals can't survive long. The relationship is delicate — small temperature changes break it.
When ocean water gets TOO WARM, corals expel their algae. The coral turns white. This is called:
Threats. CLIMATE CHANGE: warmer oceans cause bleaching. ACIDIFICATION: weakens coral skeletons. POLLUTION: nutrient runoff causes algae blooms. OVERFISHING removes ecosystem balance. SEDIMENT and dredging smother corals. Half of world's coral reefs have died since 1950. Without major intervention, scientists fear most could be gone by 2050. Conservation efforts include protected areas, coral nurseries (growing heat-resistant corals), and reducing emissions.
Reef Watch
Watch a video of a healthy coral reef vs a bleached one. The contrast is heartbreaking. Each colorful coral represents thousands of generations of life. Many can still be saved with action.
Coral reefs are some of Earth's most beautiful ecosystems. They're also among the most threatened. Protecting them is one of conservation's great challenges of our time.
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