In the context of aquatic ecosystems, what does "bioavailable" refer to?

In the context of aquatic ecosystems, "bioavailable" specifically refers to substances that organisms can assimilate, which means these substances are in a form that can be taken up and used by living organisms. This concept is important in understanding nutrient cycles, contaminant availability, and overall ecosystem health. For example, when nutrients such as phosphorus are bioavailable, they can be used by plants and algae to grow. In contrast, if substances are not bioavailable, they remain in the environment without contributing to the biological processes within the ecosystem. This can pertain to both beneficial nutrients and harmful contaminants, emphasizing how the form and state of a substance influence its potential impact on living organisms. Therefore, understanding bioavailability is crucial for assessing the health of aquatic life and managing ecosystems effectively.