[2026] PTE Academic Reading - Multiple Choice, Multiple Answers

Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals.These vibrant marine environments are currently facing an unprecedented threat from coral bleaching, a phenomenon primarily triggered by rising ocean temperatures.When water temperatures become too warm, corals expel the symbiotic algae, known as zooxanthellae, that live in their tissues and provide them with food.Without these algae, the coral loses its color, turns white, and begins to starve, although it is not immediately dead.In addition to thermal stress, ocean acidification, caused by the absorption of atmospheric carbon dioxide, hinders the ability of corals to build their skeletons.This process lowers the pH of the water, reducing the availability of carbonate ions necessary for calcification.The degradation of reefs has profound socioeconomic consequences, as they protect coastlines from erosion and support global fishing industries.Furthermore, coral reefs are a vital source of tourism revenue for many developing nations, making their preservation an economic as well as an environmental priority.While some corals show signs of resilience, large-scale restoration efforts and global carbon emission reductions are required to ensure their survival.