What would indicate a healthy watershed in terms of macroinvertebrates?

A healthy watershed can be indicated by the presence of sensitive macroinvertebrates. These organisms are typically more vulnerable to pollution and environmental changes, so their presence suggests that the water quality is good and the habitat is suitable for a variety of aquatic life. Sensitive macroinvertebrates often require specific conditions, such as high levels of dissolved oxygen and clean water, to thrive, making them excellent indicators of ecosystem health.

While the presence of diverse species is also an important indicator of a healthy ecosystem, it's particularly the sensitive species that provide strong evidence of favorable water conditions. Their survival in a given habitat indicates that it has not been significantly impacted by pollutants or other stressors.

In contrast, the absence of all macroinvertebrates signifies extreme environmental stress or pollution, which would be indicative of a severely compromised watershed. Similarly, the presence of only hardy species may suggest that only those organisms capable of surviving in degraded conditions remain, thereby reflecting poor water quality. Thus, the presence of sensitive macroinvertebrates truly aligns with the characteristics of a healthy watershed.