Which nutrient is often responsible for algal blooms in freshwater systems?

Phosphorus is often identified as the nutrient primarily responsible for algal blooms in freshwater systems. This is because phosphorus serves as a critical limiting nutrient for algae growth. When phosphorus is present in excess, typically from agricultural runoff, wastewater discharge, or other sources, it can lead to rapid algae proliferation.

These algal blooms can deplete oxygen levels in the water, leading to hypoxic conditions detrimental to aquatic life. In addition, some algal blooms produce toxins that can harm wildlife and pose health risks to humans. Therefore, managing phosphorus levels is crucial in preventing algal blooms and maintaining healthy freshwater ecosystems.

While nitrogen also plays a role in stimulating algae growth, phosphorus is often considered more significant in freshwater environments due to its limitation and potential for eutrophication. The other nutrients mentioned, like potassium and calcium, are generally not the primary contributors to algal blooms in freshwater systems.