Ecological_Response_Curves

RECOMMENDATIONS OF THE AD-HOC
WORKING GROUP OF THE NORTH
CAROLINA ECOLOGICAL FLOWS
SCIENCE ADVISORY BOARD

JULY 16, 2013
Conducted by: RTI and USGS
Funded by: Environmental Defense Fund, NC DENR, and NC WRC
BASIS
•North Carolina General Assembly Law 1743 requires NCDENR to determine the minimum flows needed to maintain ecological integrity of surface waters
•Quantitative relationships between changes in flows and health of biologic assemblages within surface waters have not bee previously established for North Carolina
•Ad ad-hoc working group of the EFSAB has been working to derive data-based correlations between changes in surface water flows and ecological response considering both fish and benthos
•The timeframe and resources dedicated to this effort have been limited
•Based on the data available and analysis completed to date, the members of the ad-hoc working group have reached consensus on a set of recommendations

RECOMMENDATIONS
1.The diversity of specifies within the riffle-run guild should be used as the basis for measure of ecological integrity for fish populations using the Shannon-Weaver Index. Ecological integrity of benthos should be based on EPT richness.
2.A reduction in fish diversity or benthos species richness of 10 percent or more represents a probable violation of ecological integrity.
3.Five metrics should be considered by NCDENR for evaluation further alterations of surface water flow conditions:
i.Decrease in annual 30-day minimum flow;
ii.Summer eco-deficit;
iii.Fall eco-deficit;
iv.Winter eco-deficit;
v.Spring eco-deficit.
4.The statistica model employed to establish ecological responses to changes in flow metrics should be based on:
i.Fish data normalized by the 80th percentile Shannon-Weaver index value by drainage basin;
ii.Benthic data normalized by the 80th percentile EPT Richness value (within the “excellent” DWQ Benthic Site Condition Class;
iii.Non-linear 80th quantile regressions of the normalized data.
5.Further data collection and research should be undertaken to enhance the preliminary flow-biology relationships developed through the work of the ad-hoc advisory group.

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RIFFLE-RUN FISH GUILD RESPONSE CURVES
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BENTHIC RICHNESS RESPONSE CURVES
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RESPONSE TO DECREASES IN 30-DAY MINIMUM FLOWS
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