The status and seasonal dynamics of fish and benthic invertebrate populations in relation to organic and inorganic material inputs and surface mining impacts in three Virginia headwater streams

Abstract

Study of two streams impacted by surface-mining and a similar unimpacted reference stream demonstrated that alkalinity, conductivity, hardness, and sulfate were elevated in the former despite reclamation treatment of the watersheds three to five years earlier. The mined-watershed streams carried a heavy benthic sediment burden, due primarily to the continued erosion from the mined areas and from abandoned haul roads. Inorganic sediment in the mining-impacted streams covered the natural rubble substrate, smoothing the bottom, filling in pools, and impacting the processing of allochthonous organic material, the principal energy source. Fine-particle organic material was trapped in the sediment, but density of larger particles was reduced, possibly due to increased transport over the smoothed substrate.

Benthic invertebrate and fish density, biomass, and diversity were consistently lower in the mining-impacted streams. The pattern of fish and benthic invertebrate recovery following a major flood was slow but unique in all streams. The benthic and fish communities of headwater streams are naturally subject to decimation by flooding, but sediment-mediated habitat and food degradation may further limit invertebrate and fish populations in disturbed systems.

This study demonstrates that sedimentation can be a severe and long-term after-effect of surface mining, even in the absence of acid drainage. Terrestrial reclamation did not result in lotic reclamation and recovery. The inclusion of water quality criteria in the administration of mined-land reclamation would promote terrestrial management practices conducive to aquatic systems recovery.