What Are the Primary Producers of Coral Reefs?

The primary producers are zooxanthellae—microscopic algae living symbiotically within reef-building corals. Through photosynthesis, they convert sunlight into energy, producing oxygen and organic compounds that nourish the coral and drive calcium carbonate deposition, forming the reef structure. In return, the coral provides shelter, nutrients, and a stable environment. This mutualism is fundamental to reef health and productivity.