Hydropeaking Extirpates River Insects

Hydropower produces 19% of the world's electricity--far more than all other renewable sources combined. In the face of mounting climate-change effects, the rush to this profuse energy source is expected to continue. However, hydroelectric dams can also produce a number of environmental consequences, many of which are unrecognized or understudied. Writing in an article for BioScience, an interdisciplinary team led by Theodore A. Kennedy of the US Geological Survey identifies one such threat: these dams' ability to devastate aquatic insect populations and the food webs that those insects underpin. One of hydropower's benefits as an energy source is that water releases can be timed to match periods of peak electrical demand. However, say the authors, such releases create "an extensive intertidal zone along river shorelines that is absent from natural rivers and to which freshwater organisms are not adapted." The threat may be most dire for aquatic insects who lay their eggs nearshore, where they are damaged by varying water levels that expose them to air. In lab tests of mayfly and caddisfly egg viability, the authors found that even "brief desiccation markedly reduced egg viability." Putting their laboratory results to a real-world test, the authors recruited a group of citizen scientist river rafters to collect thousands of insect samples in a Grand Canyon section of the Colorado River. Lower abundances of insects that lay their eggs nearshore were expected. The results...
Source: BioScience Press Releases - Category: Biology Source Type: news