Estimating benthic secondary production from aquatic insect emergence in streams affected by mountaintop removal coal mining, West Virginia, USA

Mountaintop removal and valley filling is a coal mining method that results in burial of headwater streams.  As a result of recent litigation, rapid methods for measuring ecosystem functions are needed for more appropriate permitting and mitigation strategies.  We measured emergence of aquatic insects in the Twentymile Creek, WV watershed from Autumn 2007 through Summer 2008.  Three emergence traps were placed in each of 10 streams (5 forested / 5 mined) for 14-31 days each season.  Abundance, biomass, and production were highly variable among streams and seasons and there were no significant differences between mined and forested treatments.  Annual benthic production estimates ranged from 10-55 g AFDM m^-2 yr^-1.  Forested streams had significantly higher production of Ephemeroptera, Plecoptera, and Trichoptera (EPT), whereas production in mined streams was primarily attributed to Nematocera.  EPT production was negatively correlated with stream conductivity and positively correlated with benthic macroinvertebrate index scores.  In mined streams, benthic production also increased with distance from valley fills.  While we found no differences in total secondary production between treatments, functional metrics of stream health, such as EPT production, were correlated with structural assessment methods and can provide additional data for more accurately mitigating stream loss.