|Title||Associating metrics of hydrologic variability with benthic macroinvertebrate communities in regulated and unregulated snowmelt-dominated rivers |
|Publication Type||Journal Article |
|Year of Publication||2017 |
|Authors||Steel, A. E., Peek R. A., Lusardi R. A., & Yarnell S. M. |
|Journal||Freshwater Biology |
|Keywords||altered streams, environmental flows, invertebrate community, Sierra Nevada, snowmelt recession |
|Abstract||1. Dams and diversions in rivers often alter flow regimes, which in turn can affect stream
biota, particularly when the novel conditions are dramatically different from those under
which native species evolved.
2. Management of regulated rivers can include development of environmental flows that seek
to restore ecological integrity. However, designing a flow regime that adequately supports
aquatic biodiversity requires quantifiable metrics of hydrologic variability that directly relate
to aquatic species diversity.
3. This study examined both regulated and unregulated montane rivers over 3 years within
the marked seasonality of California’s Mediterranean climate to determine which quantifiable
elements of a flow regime were most correlated with changes in the biologic community,
using stream invertebrates during the summer low flow period as an indicator.
4. Boosted regression trees were used to assess relationships between quantifiable metrics of
flow regimes and the invertebrate community. Non-metric multidimensional scaling and a
multi-response permutation procedure were used to analyze general trends in invertebrate
assemblage patterns between rivers and years. Results indicated that hydrologic alteration
corresponded to differences in invertebrate community composition, and that metrics
related to the spring snowmelt recession and variability in summer water temperature had
the greatest relative influence on invertebrate community diversity.
5. Rivers exhibiting longer duration spring recessions, lower daily rates of change during the
spring recession, and stable water temperatures during summer supported relatively higher
invertebrate community diversity. These relationships suggest that quantifiable metrics
associated with seasonal flow variability and predictability should be an integral part of
environmental flow design and monitoring.