What role does algae play in water bodies?

Algae play a multifaceted role in water bodies, significantly impacting aquatic ecosystems. They are primary producers, meaning they can photosynthesize and contribute to the oxygen levels in the water, which is vital for the survival of many aquatic organisms. However, this role can become complicated during algal blooms, which can lead to several problems. When algae proliferate excessively, they can produce toxins harmful to both aquatic life and humans, as well as cause issues with taste and odor in drinking water.

These blooms can deplete oxygen in the water when they die off and decompose, leading to hypoxic conditions that can harm fish and other wildlife. Thus, while algae are beneficial in regulated amounts, their unchecked growth can pose significant challenges in water quality and ecosystem health. This dual nature of algae—both beneficial and potentially harmful—highlights why the selected answer accurately captures the complexity of algae's role in aquatic environments.