How do multiple stressors impact stream ecosystems?
Multiple stressors can have a wide range of impacts on stream ecosystems. The combined effects of multiple stressors can be greater than the effects of each individual stressor alone. Multiple stressors can negatively affect the physical, chemical, and biological conditions in streams, leading to reduced water quality, altered habitat, and declines in populations of fish and other aquatic species. Excessive nutrients, sediment, and contaminants in the water can alter the chemistry and biology, reduce water quality, and cause declines in biodiversity. In addition, multiple stressors from land-use activities (e.g., roads, development, and agricultural activities) can degrade streams, blocking fish passage and fragmenting habitats. All of these impacts can have long-term effects on stream ecosystems and downstream systems.