14 DAY TRIAL // Whenever people decide to settle in an area, they begin modifying the environment so that it best suits them. These urban developments cause massive damage to native species of fish and aquatic insects, a new investigation has uncovered. The researchers behind it say that the old idea, according to which the early stages of development do not affect the environment and local ecosystems, is very wrong. The study was carried out by experts at the United States Geological Survey (USGS).
“When the area of driveways, parking lots, streets and other impervious cover reaches 10 percent of a watershed area, many types of pollution sensitive aquatic insects decline by as much as one third, compared to streams in undeveloped forested watersheds. We learned that there is no ‘safezone,’ meaning that even minimal or early stages of development can negatively affect aquatic life in urban streams,” says USGS biologist Tom Cuffney, a member of the research team that carried out the study.
“Stream protection and management is a top priority of state and local officials, and these findings remind us of the unintended consequences that development can have on our aquatic resources. The information has been useful in helping us to predict and manage the future impacts of urban development on streams and reinforces the importance of having green infrastructure to control stormwater runoff and protect aquatic life,” adds the coordinator of the Chesapeake Stormwater Network, Tom Schueler.
One of the main mechanisms through which urban developments act on sensitive species is indirect, through the presence of pavement, sidewalks and other types of urban land covers. When it rains, water falls on these impermeable covers, and is transported into streams a lot faster than it would have otherwise been. Therefore, water levels vary widely over very short time spans, and this is very detrimental to aquatic species. These changes in level also influence temperature, and things become even worse when considering that runoff waters can also contain fertilizers, insecticides, and other complex chemical compounds. These can easily kill fish and insects, the USGS team says.