What is a key feature of benthic macroinvertebrates that indicates the health of a stream?

A high diversity of species among benthic macroinvertebrates is a key indicator of stream health because it reflects a balanced and resilient ecosystem. These organisms, which include insects, crustaceans, and other small animals that live in or on the bottom of aquatic environments, are sensitive to changes in water quality and habitat conditions.

When a stream ecosystem is healthy, a wide variety of macroinvertebrates can thrive because they have the necessary food resources, suitable habitat, and appropriate water quality. A diverse community suggests that the stream can support various ecological needs and that it is not dominated by pollution-tolerant species, which might be more prevalent in degraded conditions.

The presence of algae, fish species, and amphibian larvae can provide some information about ecosystem health, but they do not offer the same level of insight into the overall condition of the stream as the diversity of benthic macroinvertebrates. For example, while algal blooms can indicate nutrient overload, they do not reflect the community structure or health of benthic organisms. Similarly, the number of fish species and existence of amphibian larvae can be influenced by factors other than water quality, such as habitat complexity or seasonal variations. Thus, species diversity among benthic macroinvertebrates serves