<h4>Widespread Coral Bleaching in the Great Barrier Reef</h4><p>Recent <strong>aerial surveys</strong> conducted by <strong>Australian authorities</strong> have confirmed extensive <strong>coral bleaching</strong> across <strong>two-thirds</strong> of the <strong>Great Barrier Reef (GBR)</strong>. This alarming discovery signals a severe and ongoing threat to one of the world's most iconic natural wonders.</p><p>The phenomenon of <strong>coral bleaching</strong> is primarily driven by rising ocean temperatures, which are directly linked to <strong>climate change</strong>. These elevated temperatures stress the corals, causing them to expel the symbiotic algae crucial for their survival.</p><div class='key-point-box'><p>The current widespread bleaching event underscores the urgent need for global action. Without significant reductions in <strong>greenhouse gas emissions</strong>, the long-term viability of the GBR and other coral ecosystems remains critically endangered.</p></div><h4>Understanding Coral Bleaching</h4><p><strong>Coral bleaching</strong> occurs when corals expel the colorful algae, known as <strong>zooxanthellae</strong>, that live within their tissues. These algae provide corals with most of their food through photosynthesis and give them their vibrant colors.</p><p>When stressed by factors like increased water temperature, pollution, or extreme low tides, corals expel these algae. The coral then turns white, revealing its calcium carbonate skeleton, hence the term 'bleaching'.</p><div class='info-box'><p><strong>Zooxanthellae:</strong> Microscopic algae that live in a <strong>symbiotic relationship</strong> with coral polyps, providing nutrients and color.</p></div><h4>Impacts on the Great Barrier Reef</h4><p>The <strong>Great Barrier Reef</strong> is a UNESCO World Heritage site and a vital ecosystem supporting immense biodiversity. Widespread bleaching events devastate coral colonies, leading to significant coral mortality if conditions do not improve.</p><p>This degradation impacts the entire marine food web, affecting fish populations, sea turtles, and other species that rely on the reef for habitat and food. It also has profound economic implications for industries like tourism and fisheries.</p><div class='exam-tip-box'><p>For <strong>UPSC Mains GS-III (Environment)</strong>, understanding the causes and consequences of coral bleaching, especially in the context of global warming, is crucial. Be prepared to discuss mitigation and adaptation strategies.</p></div>