Taxon and trait-based sampling curves can be used as a tool for assessing impairment in salinized headwater streams

•Six Appalachian headwater streams were sampled for benthic macroinvertebrates.•We compared richness-sample effort patterns in reference and salinized streams.•Taxon sampling curves were used to identify sampling effort needed to collect taxa.•Taxon and trait-based sampling curves support equal and greater samples per stream.•Sampling curves can provide diversity estimates when sampling is incomplete.