Effects of mountaintop removal coal mining on the diversity and secondary productivity of Appalachian rivers

Abstract

Land cover change often alters the chemical regime and reduces the diversity of sensitive taxa in downstream aquatic ecosystems. The consistently elevated ionic strength associated with surface coal mines has been implicated in extirpating sensitive taxa throughout many Appalachian streams. We quantified secondary production at three sites spanning a gradient of mining impacts in the Mud River (West Virginia, U.S.A.) by sampling macroinvertebrates monthly from 2012 to 2013. Not only do we observe significant changes in aquatic insect community structure driven by the loss of sensitive taxa in mined watersheds, but we show that these losses translate directly to depressed biomass throughout the year becoming most apparent when pollutant concentrations rise during summer baseflow. These distinct seasonal patterns result in threefold decreases in total insect production and EPT production ∼1-km downstream of an unmined reach. Farther downstream, where pollutant concentrations are much higher, total annual productivity is similar to the unmined reach, but suffers from a 31% loss of taxa comprising production and altered timing of that production. Mayflies were the insects most notably affected by the chemical alteration. Whereas mayflies accounted for ∼14% of total production in our upstream, unmined site, they only accounted for 0.2% of production at the most impacted site. We conclude that elevated ionic strength depresses insect production by preventing sensitive taxa from completing their life cycles in mining-impacted streams. Because surface coal mining dominates the Central Appalachian landscape, such altered production patterns are likely a common landscape feature impacting regional food webs