Mine spoil spoils downstream ecology

Posted on October 1, 2014

The central Appalachian area of the USA, in the states of Virginia, West Virginia and Kentucky, is a global hotspot of freshwater fish biodiversity. However, since the 1960s, Appalachian environments have been threatened by mountaintop mining, which has expanded greatly in recent years and is now the main cause of landuse change in the region. Mountaintop mining involves exposing coal seams by removing surface soil and rock and dumping it in adjacent valleys, a process that can lower mountain heights by up to 300 m. The practice affects downstream surface waters by reducing base flows, boosting loads of fine sediment, and increasing stream conductivity and concentrations of metals. Losses of invertebrate species have been linked to mountaintop mining, but until recently no studies on the temporal responses of fish assemblages had been carried out. To help fill this knowledge gap, fish samples collected from the Guyandotte River basin in 1999-2001 were compared with those taken in 2010-2011 using similar electrofishing techniques. Fish assemblages exposed to the effects of mining had fewer species, with lower abundances and less biomass than reference assemblages across years and seasons. The observed differences couldn’t be explained by changes in physical habitat conditions, but rather seemed to be related to the effects of water quality (in particular, levels of conductivity and selenium) on the availability and quality of invertebrate prey.

Reference: Hitt, N.P. & Chambers, D.B. 2014. Temporal changes in taxonomic and functional diversity of fish assemblages downstream from mountaintop mining. Freshwater Science 33(3), 915–926. http://www.bioone.org/doi/pdf/10.1086/676997