Which nutrient typically limits aquatic plant growth in nutrient-rich waters?

In nutrient-rich waters, phosphorus is often the key nutrient that limits the growth of aquatic plants. While many nutrients are necessary for plant growth, phosphorus is typically found in lower concentrations compared to nitrogen or potassium in many aquatic systems. When phosphorus is present in adequate quantities, it can lead to excessive plant growth, particularly in the form of algae blooms. This phenomenon is referred to as eutrophication, which can severely disrupt aquatic ecosystems by depleting oxygen levels and blocking light, consequently harming fish and other aquatic life.

The specific role of phosphorus in promoting plant growth is due to its involvement in critical processes such as energy transfer (as part of ATP), photosynthesis, and nucleic acid synthesis. While calcium is important for cell structure, carbon is essential for photosynthesis, and oxygen is necessary for respiration, none of these nutrients typically act as the primary limiting factor in nutrient-rich waters like phosphorus does. Thus, recognizing the role of phosphorus helps in understanding how to manage aquatic environments and maintain ecological balance.