Aquatic ecosystems play a crucial role in nutrient cycling by facilitating the movement and transformation of nutrients like nitrogen and phosphorus through various biological processes. They serve as sites for decomposition, where organic matter is broken down and nutrients are released back into the water, promoting biodiversity and supporting food webs. Wetlands, rivers, and lakes filter pollutants and regulate nutrient availability, helping maintain a healthy environment and supporting aquatic life. These ecosystems thus contribute significantly to overall ecosystem health and balance.