The Great Barrier Reef (GBR) is a massive coral reef. It stretches for 1,500 miles off the northeastern coast of Australia. It suffered the worst bleaching event on record over the past year, according to the Australian Institute of Marine Science (AIMS). Corals are tiny marine animals. They are invertebrates. They live in stony structures formed from calcium carbonate. Over time, they can build so many of these “skeletons” that an entire underwater habitat — a “reef” — is formed. Coral reefs shelter thousands of other species. They protect coastlines against ocean currents and storm surges. The GBR is the largest such reef in the world. Normally, corals live symbiotically with algae. That's a marine plant. The algae lend corals their distinctive colors. They're also a source of food. When water temperatures rise , however, the algae are expelled. Corals turn white as a result. That process is called “bleaching.” Deprived of food, many corals don’t survive. In its 2024/2025 Annual Summary Report, published Wednesday, AIMS detailed “high to extreme bleaching ... across all three regions of the GBR." It added that, "Regional declines ranged between 14% and 30% compared to 2024 levels, with some individual reefs experiencing coral declines of up to 70.8%.” At fault for the die-off: rising ocean temps fueled by climate change, a pair of destructive cyclones, and a surge in predatory sea stars that feast on coral. Australia’s government has already started sea star hunting programs. They are also pursuing ways to protect and replenish existing coral populations. Reflect: What places or parts of nature do you think are worth protecting? Photo of bleached coral from Great Barrier Reef from Wikimedia Commons courtesy of Matt Kieffer.
