The loss of sensitive species in streams begins to occur at the initial stages of urban development, according to a new study by the USGS. The study found that streams are more sensitive to development than previously understood.
"We tend not to think of waterways as fragile organisms, and yet that is exactly what the results of this scientific investigation appear to be telling us," said USGS Director Marcia McNutt. "Streams are more than water, but rather communities of interdependent aquatic life, the most sensitive of which are easily disrupted by urbanization."
Contaminants, habitat destruction, and increasing streamflow flashiness resulting from urban development can degrade stream ecosystems and cause degradation downstream with adverse effects on biological communities and on economically valuable resources, such as fisheries and tourism.
For example, by the time urban development had approached 20 percent in watersheds in the New England area, the aquatic invertebrate community had undergone a change in species composition of about 25 percent.
The study also found that the health of highly-degraded streams can be improved by implementing management actions that are designed to reduce specific stressors.
"Biological communities were not resistant to even low levels of urban development. In the study sensitive invertebrate species were being lost over the initial stages of development in relatively undisturbed watersheds," said Dr. Gerard McMahon, lead scientist on the study. "Understanding how stream ecosystems are impacted by urban development can assist in the development of management actions to protect and rehabilitate urban stream ecosystems."
Multiple streams in nine metropolitan areas (http://water.usgs.gov/nawqa/urban/html/wherewestudied.html) across the continental U.S. were sampled to assess the effects of urban development on stream ecosystems. Study areas include Atlanta, Ga., Birmingham,
|Contact: Kara Capelli|
United States Geological Survey