What type of organisms are collected to monitor water quality in streams?

Macroinvertebrates are collected to monitor water quality in streams because they are sensitive indicators of environmental conditions and changes in water quality. These organisms, which include insects, crustaceans, and worms, play important roles in aquatic ecosystems. Their presence, abundance, and diversity can provide valuable insights into the health of a stream or river. For instance, certain macroinvertebrate species are found only in clean, well-oxygenated water, while others can tolerate or thrive in polluted conditions. By examining the community composition of macroinvertebrates, wildlife officers and ecologists can assess the ecological integrity of freshwater ecosystems.

In contrast, large fish species can be influenced by many factors besides water quality, such as habitat availability and fishing pressure, making them less reliable indicators for water quality assessments. Aquatic plants also respond to changes in water quality, but they can be affected by other variables such as nutrient levels and competition for sunlight. Floating debris, while it may indicate pollution or littering, does not provide specific information about the biological conditions of the water body. Overall, macroinvertebrates are the preferred organisms for effectively monitoring stream water quality.