Algal blooms can often lead to which environmental issue?

Algal blooms primarily lead to oxygen depletion in aquatic environments. When conditions such as nutrient overload, often from agricultural runoff, promote the rapid growth of algae, these blooms can cover the surface of water bodies. This coverage prevents sunlight from reaching other aquatic plants, which in turn affects their ability to photosynthesize and produce oxygen.

As the algae die off, they are decomposed by bacteria, a process that consumes dissolved oxygen in the water. This depletion can result in hypoxic (low oxygen) conditions or even anoxic (no oxygen) conditions, severely impacting aquatic life. Fish and other organisms that rely on oxygen can suffocate or become stressed in these environments, leading to significant ecological consequences.

In contrast, water purification is typically an outcome of healthy ecosystems, and algal blooms usually disrupt this balance rather than enhance it. While some biodiversity may thrive in nutrient-rich conditions initially, the long-term effects of oxygen depletion can detrimentally affect overall biodiversity. Soil erosion is largely unrelated to algal blooms as it pertains to land rather than water dynamics. Thus, oxygen depletion is the most direct environmental issue associated with algal blooms.