Zooxanthellae are crucial to the vitality of which ecosystem?

• A. Deep-sea vents
• B. Coral reef ecosystems
• C. Polar ice shelves
• D. Open ocean gyres

Answer: (B)

Zooxanthellae form a mutualistic partnership with corals, providing energy through photosynthesis. These algae live inside the coral’s tissues and share the sugars they produce with the coral, supplying most of its energy needs. That energy fuels rapid coral growth and the production of calcium carbonate skeletons, which build the reef structure. In warm, clear, sunlit tropical waters, this relationship is essential for the high productivity and biodiversity seen in coral reefs. When stressed by heat or pollution, corals expel the zooxanthellae, lose color, and can suffer reduced growth and reef degradation. Because this energy-supplying partnership is so crucial, zooxanthellae are fundamental to coral reef ecosystems.