In aquatic ecosystems, dam construction and the diversion of water for consumptive use have substantially altered the natural hydrology of streams; and climate change is likely to further affect hydrological regimes, the frequency of extreme events (droughts and floods), and hydrologic variance. Variation in flow is viewed as one of the most important processes for structuring communities and ecosystem functioning in streams. An increased frequency of low flow events is of particular concern because it is during low flow that human water use, such as diversions, ground-water abstraction, and water use for irrigation, are in direct conflict with the maintenance of a minimum flow for ecological function. My thesis research explores how changes to the natural flow regime, specifically lowered flow, directly and indirectly affect stream communities. Which academic category is most appropriate?