Application of a New Species‐Richness Based Flow Ecology Framework for Assessing Flow Reduction Effects on Aquatic Communities

Abstract

Water-resources managers are challenged with maintaining a balance among beneficial uses throughout river networks and need robust means of assessing potential risks to aquatic life resulting from flow alterations. This study generated ecological limit functions from species-streamflow relations to quantify potential fish richness response to flow alteration and compared results to currently accepted streamflow management guidelines. Modeled responses of absolute richness change were watershed specific and varied among sample sets derived from hydrologic unit classifications of different sizes (large HUC 6 basins to regional scale HUC 8). With a 20% flow reduction, 10% of HUC 8 predicted a richness decrease in one or more taxa. While absolute richness change was consistent across streams within a HUC, percent richness change was stream size dependent. Comparisons with Instream Flow Incremental Methodology habitat models predicted habitat loss greater than percent richness change; however, predictions for habitat and richness decreased similarly as stream size decreased. Watershed-specific responses from flow reductions could allow water-resources management decisions to be made locally based on the predicted richness change for certain sized streams. Quantitative results highlight the utility of a richness-based framework for generating watershed-specific risk assessments that validate and inform currently employed water-resources management practices.

Wastewater reuse and predicted ecological risk posed by contaminant mixtures in Potomac River watershed streams

“…Low‐order streams are critical hotspots of aquatic biodiversity and habitat variability (Biggs et al, 2017; Freeman et al, 2007; Meyer et al, 2007), while medium‐order streams have been shown to support rich fish assemblages (Rapp et al, 2020). In the Potomac River watershed, a combined 5387 km of first‐, second‐, and third‐order streams were impacted by direct or upstream discharges of municipal and/or industrial wastewater (23% of combined first‐, second‐, and third‐order stream kilometers).…”

R2Cross: A Web‐Based Decision Support Tool for Instream Flows

“…Users familiar with R programing language can calculate a suite of ecological streamflow statistics with EflowStats package (Mills and Blodgett 2020). A new framework that assesses biological alteration from flow alteration (Rapp et al 2020) can be implemented with the elfgen R package (Kleiner et al 2020). Konrad (2011) developed a workbook-VBA-based algorithm that calculates an array of hydrologic statistics and generates different scenarios for allocating and protecting streamflow.…”

“…A new framework that assesses biological alteration from flow alteration (Rapp et␣al. 2020) can be implemented with the elfgen R package (Kleiner et␣al. 2020).…”