Assessing relationships between human land uses and the decline of native mussels, fish, and macroinvertebrates in the Clinch and Powell river watershed, USA

Abstract

The free-flowing Clinch and Powell watershed in Virginia, USA, harbors a high number of endemic mussel and fish species but they are declining or going extinct at an alarming rate. To prioritize resource management strategies with respect to these fauna, a geographical information system was developed and various statistical approaches were used to relate human land uses with available fish, macroinvertebrate, and native mussel assemblage data. Both the Ephemeroptera, Plecoptera, Trichoptera (EPT) family-level index, and the fish index of biotic integrity (IBI) were lowest in a subwatershed with the greatest coal mining activity (analysis of variance [ANOVA], p < 0.05). Limited analyses in two other subwatersheds suggested that urban and agricultural land uses within a specified riparian corridor were more related to mussel species richness and fish IBI than land uses in entire catchments. Based on land uses within a riparian corridor of 200 m x 2 km for each biological site in the watershed, fish IBI was inversely related to percent cropland and urban area and positively related to pasture area (stepwise multiple regression, R2 = 0.55, p < 0.05). Sites less than 2 km downstream of urban areas, major highways, or coal mine activities had a significantly lower mean IBI value than those more than 2 km away (ANOVA, p < .05). Land use effects included poorer instream cover and higher substrate embeddedness (t test, p < 0.05). Weaker land use relationships were observed for EPT and mussel species richness. Episodic spills of toxic materials, originating from transportation corridors, mines, and industrial facilities, also have resulted in local extirpations of native species. particularly mussels. The number of co-occurring human activities was directly related to stream elevation in the Clinch River, with more human land uses in headwater areas. Approximately 60% of known U.S. Fish and Wildlife mussel concentration sites in the watershed are located within 2 km of at least two land use sources identified as potentially stressful in our analyses. Our results indicate that a number of land uses and stressors are probably responsible for the decline in native species. However, protection of naturally vegetated riparian corridors may help mitigate some of these effects.

Stream Condition in Piedmont Streams with Restored Riparian Buffers in the Chesapeake Bay Watershed1

“…Past research has shown that both pasture and suburban/urban landuses can have substantial sediment loadings into streams (Wahl et al. , 1997; Diamond et al. , 2002; Richardson and Jowett, 2002; Riley et al.…”

Water and Sediment Quality in the Clinch River,Virginia andTennessee,USA, over Nearly Five Decades

“…Although the above water and sediment quality constituents have been monitored in the Clinch River by government agencies for several decades, the resulting water and sediment quality data had not been analyzed previously for freshwater mussel conservation purposes. Prior studies have cited a variety of water environmental factors, including land use influences and contaminated water and sediments, as priority stressors for mussels in the Clinch River (Diamond and Serveiss, ; Diamond et al ., ; Locke et al ., ). However, which stressors and/or stressor‐source watershed activities have contributed most substantially to mussel populations' historic declines is not known; nor is it known which (if any) historic stressors remain as significant current threats.…”

Reach‐Scale Comparison of Habitat and Mollusk Assemblages for Select Sites in the Clinch River with Regional Context

“…Several competing hypotheses have been posed to explain spatial and temporal patterns of decline and persistence in the Clinch River. These hypotheses include, but are not limited to, water‐quality degradation caused by current coal and gas extraction, pollutants present in sediments from past energy extraction, changes in land use or land cover, water quality degradation from agricultural practices, episodic acute chemical spills, presence of coal fines in habitats occupied by mollusks, and physical degradation of local habitat (Diamond et al ., ; Van Hassel, ; Krstolic et al ., ; Johnson et al ., ; Jones et al ., ). Several of these hypotheses are explored elsewhere in this series of articles and in supporting documents (Krstolic et al ., ; Johnson et al ., ; Price et al ., ).…”

“…Confounding abiotic and biotic factors acting at several spatial and temporal scales likely shape mussel assemblages. Several researchers have linked catchment‐scale land use, underlying geology, and soil type to richness and abundance (Arbuckle and Downing, ; Diamond et al ., ; McRae et al ., ; Poole and Downing, ). Others have found that abundance is associated with local channel geomorphology (Vannote and Minshall, ; Church, ; Howard and Cuffey, ; McRae et al ., ; Stone et al ., ; Gangloff and Feminella, ).…”

“…Specifically, these studies demonstrated that mussels are associated with stable reaches, which act as refugia during high flows. Riparian vegetation, local land use, and flow regime have also been associated with differences in mussel assemblages (Di Maio and Corkum, ; Morris and Corkum, , ; Diamond et al ., ).…”