The primary source of energy for aquatic plants is sunlight. Plants, including those that grow in aquatic environments, undergo photosynthesis, a process that converts light energy into chemical energy. Through this process, aquatic plants utilize sunlight to synthesize glucose and other organic compounds from carbon dioxide and water. This energy transformation is essential for their growth and serves as the foundation for the aquatic food web, supporting various organisms, such as herbivorous fish and other wildlife. Thus, sunlight is crucial for sustaining life in aquatic ecosystems.