What characteristic defines aquatic plants that live below the water surface?

Aquatic plants that thrive below the water surface play a crucial role in the aquatic ecosystem, one of which is their ability to contribute to water oxygenation. Through the process of photosynthesis, these submerged plants utilize sunlight (to an extent) to convert carbon dioxide and water into glucose and oxygen. The oxygen produced is released into the water, which is essential for the survival of aquatic organisms, including fish and microorganisms.

While other characteristics, such as having a specialized root structure, may also apply to certain aquatic plants, it is the direct contribution to oxygen levels in the water that is central to their ecological role. This characteristic not only supports aquatic life but also helps maintain a balanced aquatic environment, making them vital for both water quality and biodiversity.