Science informing policy
The authors found pronounced differences in the food webs of regulated and unregulated rivers, with unregulated rivers generally supporting higher rates of biodiversity. When they looked closer at the flow regimes of each river, they found that the spring snowmelt recession (the period of snowmelt during spring) was most strongly correlated with ecosystem biodiversity. The findings are important because they suggest that the spring snowmelt recession, despite receiving little attention in environmental flow management, is critical to promoting healthy and robust river ecosystems. The results also suggest that the spring snowmelt recession should be incorporated into environmental flow targets in order to enhance aquatic biodiversity, particularly in large regulated snowmelt-dominated rivers.
Instream flow science has developed over the last several decades. Importantly, today’s methods are beginning to link environmental flows to ecological indicators and biological response. The papers presented here are important because they are either regionally specific and can be incorporated quickly into environmental flow planning or shed new light on how flow regimes affect biodiversity in California rivers. To that end, these publications are informing instream flow policy throughout the state and empowering regulators to set ecologically protective flows that are scientifically defensible to protect salmon and trout, particularly during periods of resource conflict.
Dr. Robert Lusardi is the California Trout-UC Davis Wild and Coldwater Fish Scientist and Darren Mierau is California Trout’s North Coast Director.
The original articles are currently available as early online view in Freshwater Biology:
Mierau DW, WJ Trush, GJ Rossi, JK Carah, MO Clifford, and JK Howard. 2017. Managing diversions in unregulated streams using a modified percent-of-flow approach. Freshwater Biology 2017; 1-17.
Steel, AE, RA Peek, RA Lusardi, and SM Yarnell. 2017. Associating metrics of hydrologic variability with benthic macroinvertebrate communities in regulated and unregulated snowmelt-dominated rivers. Freshwater Biology 2017; 1-15.
Dr. Robert Lusardi is the California Trout-UC Davis Wild and Coldwater Fish Scientist, Dr. Jacob Katz, directs CalTrout’s Central California Region, and Dr. Peter Moyle is a distinguished Professor, Emeritus at the University of California, Davis.
WHAT THE SCIENCE SAYS