Effects of coalbed natural gas development on fish assemblages in tributary streams of the Powder and Tongue rivers

Abstract

1. Extraction of coalbed natural gas (CBNG) often results in disposal of large quantities of CBNG product water, which may affect aquatic ecosystems. We evaluated the effects of CBNG development on fish assemblages in tributary streams of the Powder and Tongue rivers. We used treatment and control, impact versus reference sites comparisons, surveys of CBNG product-water streams and in situ fish survival approaches to determine if CBNG development affected fish assemblages. 2. Several of our results suggested that CBNG development did not affect fish assemblages. Species richness and index of biotic integrity (IBI) scores were similar in streams with and streams without CBNG development, and overall biotic integrity was not related to the number or density of CBNG wells. Fish occurred in one stream that was composed largely or entirely of CBNG product water. Sentinel fish survived in cages at treatment sites where no or few fish were captured, suggesting that factors such as lack of stream connectivity rather than water quality limited fish abundance at these sites. Fish species richness did not differ significantly from 1994 to 2006 in comparisons of CBNG-developed and undeveloped streams. Biotic integrity declined from 1994 to 2006; however, declines occurred at both impact and reference sites, possibly because of long-term drought. 3. Some evidence suggested that CBNG development negatively affected fish assemblages, or may do so over time. Specific conductivity was on average higher in treatment streams and was negatively related to biotic integrity. Four IBI species richness metrics were negatively correlated with the number or density of CBNG wells in the catchment above sampling sites. Bicarbonate, one of the primary ions in product water, was significantly higher in developed streams and may have limited abundance of longnose dace (Rhinichthys cataractae). Total dissolved solids, alkalinity, magnesium and sulphate were significantly higher in developed streams. 4. Biological monitoring conducted before the development of CBNG, and continuing through the life of development and reclamation, together with data on the quantity, quality and fate of CBNG product water will allow robust assessment of potential effects of future CBNG development worldwide.

Fish assemblage associations and thresholds with existing and projected oil and gas development

“…Species codes are first letter of genus then first four letters of specific epithet. By contrast, Davis et al (2010) found negative relations between number of gas wells and gas well density in the upstream catchment and native species richness, catostomid and ictalurid richness, number of long-lived species and familial richness. Tongue rivers, Montana-Wyoming, USA.…”

“…Davis et al (2010) found no significant differences in fish assemblage structure metrics between coal-bed natural gas development sites and control sites in tributaries to the Powder and Figure 5. Davis et al (2010) found no significant differences in fish assemblage structure metrics between coal-bed natural gas development sites and control sites in tributaries to the Powder and Figure 5.…”

Ecology of the redfin darter and a potential emerging threat to its habitat

“…Such activities, including large-scale construction, massive hydraulic fracturing and horizontal drilling, have expanded in the continental United States to access previously inaccessible natural gas reservoirs for rising energy demands (Davis et al 2010;Entrekin et al 2011). Including changes to water chemistry and deforestation, siltation is expected to be a particularly detrimental effect of NNGE activities (Williams et al 2008;Davis et al 2010;Entrekin et al 2011). Development in the Fayetteville Shale in the eastern portion of the range of E. whipplei, as in most shale-gas basins, has been extremely recent and rapid, and the effects of NNGE activities to stream biota are not currently well understood (Entrekin et al 2011).…”

“…Shepard et al (1993) found an overall decline of Gulf darters (Etheostoma swaini) and an increase of rough shiners (Notropis baileyi) in the presence of product water in the Black Warrior system. Davis et al (2010) focused on coarse-scale community metrics (e.g., Indices of Biotic Integrity), and at this scale had difficulty elucidating shifts in fish community composition, but did find that many ephemeral streams currently experiencing sustained treated product water outflow were capable of supporting fishes. Compounding the difficulties faced by Davis et al (2010) is that their work was conducted on fishes in streams of the North American Great Plains ecoregion, where many species are known for being physiologically tolerant to such disturbances as rapid changes in temperature, salinity, and dissolved oxygen (Dodds et al 2004).…”

“…Davis et al (2010) focused on coarse-scale community metrics (e.g., Indices of Biotic Integrity), and at this scale had difficulty elucidating shifts in fish community composition, but did find that many ephemeral streams currently experiencing sustained treated product water outflow were capable of supporting fishes. Compounding the difficulties faced by Davis et al (2010) is that their work was conducted on fishes in streams of the North American Great Plains ecoregion, where many species are known for being physiologically tolerant to such disturbances as rapid changes in temperature, salinity, and dissolved oxygen (Dodds et al 2004). Extrapolation of the results of these studies to streams of the Fayetteville Shale is further complicated, as both former studies were conducted in coalbed methane basins, while the Fayetteville Shale is a shale gas basin.…”