Oysters are filter-feeding shellfish. They filter plankton and suspended organic matter from seawater into their mouths by opening shells as food sources. Microalgae is an important primary producer in marine ecosystem. They convert sunlight energy into organic matter through photosynthesis and provide nutrition for oysters.
In addition, organic debris is also the food source of oysters, which may come from the remains and feces of animals and plants in seawater. Oysters grow and develop by eating algae and organic debris in seawater to get the nutrients they need. Therefore, it can be said that oysters mainly rely on microalgae and organic debris in seawater to grow.