Relationships between flow variability and invertebrate communities in mountain rivers

What is it about?

Aquatic organisms are often well-adapted to the natural dynamics of the rivers where they live. When the natural patterns of flow variability are changed through human-alterations, such as dams to divert water or create hydropower, the community of organisms in the river can change. In this paper we evaluated the relationships between measurable aspects of a river hydrograph and the biological community. We compared five rivers in the west slope of the Sierra Nevada mountains, with different types and extent of flow alteration. We found that aspects of the recession limb (the naturally slow decline of water levels during the spring) were indicative of the diversity of the invertebrate community. Specifically, rivers which had a longer and more gradual decrease in flow, as well as more consistent temperatures, had higher biodiversity. These findings can be useful in designing water-releases from dams that can benefit the biological communities which live downstream.

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