Recovery of the Benthic Macroinvertebrate Community in a Small Stream After Long-Term Discharges of Fly Ash

Abstract

Recovery of the benthic macroinvertebrate community in a small east Tennessee stream impacted by fly ash discharges from a power plant was investigated over a period of 6.5 years. The rate of recovery was greatest in the first 2 years after an initial 75% reduction in coal use led to a similar reduction in ash discharges and associated contaminants; further recovery followed after all fly ash discharges ceased. Recovery of the stream progressed through two phases. In the first phase, which lasted for approximately the first 2 years, most density and richness metrics increased considerably. In the second phase of recovery, the increases in metric values were followed by declines before fluctuating in and out of the lower reference ranges for the metrics. Detrended correspondence analyses and indicator species analyses showed that changes in species composition and community structure were ongoing throughout the second phase. Thus, the first phase was characterized by species additions, while the second phase involved species replacements and shifts in community dominants. Further recovery of the macroinvertebrate community will probably depend on additional flushing of fly ash deposits from the streambed and flood plain, because their continued presence reduces habitat quality in the stream and serves as a potential source of contaminants. Further recovery also may be limited by the availability of vagile species in nearby watersheds.

How toxic is coal ash? A laboratory toxicity case study

“…A brief, independent review limited to studies that included aquatic and benthic organism exposures to ash or ash basin effluents identified only 13 published articles. Ten were field studies of benthic or fish biota in 1 lentic and 10 lotic habitats (Cherry et al 1979;Reash et al 1988;Lemly 1997;Lohner, Reash, Willet, Fletcher 2001;Lohner, Reash, Willet, Rose 2001;Lohner, Reash, Williams 2001;Smith 2003;Reash 2004Reash , 2012Otter et al 2012); and 3 were laboratory studies (Stanley et al 2013;Wang et al 2013;Greeley et al 2014a), all of which were investigations of the 2008 Tennessee Valley Authority (TVA) Kingston Fossil Plant ash spill. This imbalance between fieldand laboratory-based studies is likely due to prevailing opinions that laboratory studies should predict toxic effects in the field (Lemly 1985).…”

Bacterial tolerances to metals and antibiotics in metal-contaminated and reference streams

“…Ash residues are then commonly mixed with plant intake water before being deposited in settling basins, and this flow-through water is then typically discharged into aquatic systems (Rowe et al, 2002). Multiple studies have documented deleterious effects of coal ash on ecological systems (Rowe et al, 2002;Smith, 2003), but less is known concerning coal ash effects on microbial communities (but see Guthrie et al, 1978;Klubek et al, 1992;Stepanauskas et al, 2005).…”

Ecological Recovery Potential of Freshwater Organisms: Consequences for Environmental Risk Assessment of Chemicals

“…Studies reporting the recovery of Trichoptera have mostly focused on lotic fi lter-feeding species belonging to the family of Hydropsychidae, whereas information on the common family of Limnephilidae is scarce. Rapid recovery of Hydropsychidae was found after pesticide application, fl ooding events and heavy-metal contamination (Malmqvist et al 1991 ;Ryon 1992Ryon , 1996Smith 2003 ;Specht et al 1984 ;Yasuno et al 1982 ;Whiles and Wallace 1992 ), whereas after large-scale disturbance (Ide 1967 ), in newly established lentic systems (Barnes 1983 ;Danell and Sjoberg 1982 ;Koskenniemi 1994 ) and for other trichopteran species (Ryon 1992(Ryon , 1996Smith 2003 ), long recovery times have been reported.…”

“…Slow colonization in Ephemeroptera was observed for instance, after long-term heavy metal discharge (Ryon 1992(Ryon , 1996Smith 2003 ) or due to low ambient temperatures Flory and Milner 1999 ;Milner 1987Milner , 1994Milner et al 2000 ). In addition, the partitioning and bioavailability of the chemical stressor in relation to the typical habitat of the ephemeropteran in the aquatic ecosystem of concern might play an important role in its recovery time.…”