The health of freshwater animal and plant life is dependent on streamflow, yet identification of the flow regimes required to maintain ecological integrity remains challenging to states in the U.S. seeking to establish ecological flows that achieve environmental objectives. A new article in the Journal of the American Water Resources Association tests the relationship between decreases in streamflow and Shannon-Weaver diversity index of fish species for four flow-based habitat guilds: riffle, riffle-run, pool-run, and pool in North Carolina. The study finds that species who prefer shallow habitats, such as riffles and riffle-runs were the most sensitive to decreases in streamflow, while using all fish data greatly underestimated the response of fish species to decreases in flow. Since ecological flows are designed to protect the integrity and diversity of aquatic ecosystems, ecological flows should be established to protect those species most sensitive to changes in flow.
Nicholas Institute for Environmental Policy Solutions