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The Longitudinal Distribution of Benthic Invertebrates in Regulated and Natural Rivers Researchers: Lucy Lee and Nick Jones Project Description: Hydroelectric dams alter the magnitude and frequency of flows and can have negative effects on downstream invertebrate and fish communities. Some of these dams operate as hydropeaking facilities, which are designed to adjust the level of power generation in accordance with energy demand. This hourly variation in flow can dramatically alter the quantity and quality of habitat available to biota and the resulting effects can be direct (e.g. stranding or habitat abandonment) or indirect (e.g. depleted food production or increased physiological stress). Invertebrates are strong indicators of stream ecosystem function as they link lower trophic levels, organic matter and algae, with higher trophic levels such as fish. The zone of influence (ZOI), defined as the distance from the dam to the point of recovery to natural conditions is a useful measure to quantify impacts of impoundment. There are currently no studies that examine the longitudinal patterns of macroinvertebrate communities below hydropeaking dams and very few studies that provide measurements for ZOI. This study is a comparative examination of invertebrate distributional patterns along the longitudinal environmental gradients in natural and hydropeaking rivers. We hope to determine: 1) what are the key environmental gradients in rivers, 2) how do invertebrates respond to these environmental gradients, 3) can the zone of influence for macroinvertebrates be estimated based on functional responses, their food and habitat quality, and 3) how these environmental gradients and the responses of invertebrates compare to those found in natural rivers with and without lake outlets and tributaries. Collaborators and
Participants: Links: Spatial Distribution and Growth of Sculpin in Natural and Regulated Rivers Interesting Facts: While much interest is currently focused on flow regime characteristic, we must not forget that changes to the thermal regime of rivers can lead to fundamental impacts to the aquatic community - regardless of flow conditions.
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