Identifying Sources of Stress to Native Aquatic Fauna Using a Watershed Ecological Risk Assessment Framework

Abstract

The free-flowing Clinch and Powell River Basin, located in southwestern Virginia, United States, historically had one of the richest assemblages of native fish and freshwater mussels in the world. Nearly half of the species once residing here are now extinct, threatened, or endangered. The United States Environmental Protection Agency's framework for conducting an ecological risk assessment was used to structure a watershed-scale analysis of human land use, in-stream habitat quality, and their relationship to native fish and mussel populations in order to develop future management strategies and prioritize areas in need of enhanced protection. Our analyses indicate that agricultural and urban land uses as well as proximity to mining activities and transportation corridors are inversely related to fish index of biotic integrity (IBI) and mussel species diversity. Forward stepwise multiple regression analyses indicated that coal mining had the most impact on fish IBI followed by percent cropland and urban area in the riparian corridor (R 2 ) 0.55, p ) 0.02); however, these analyses suggest that other site-specific factors are important. Habitat quality measures accounted for as much as approximately half of the variability in fish IBI values if the analysis was limited to sites within a relatively narrow elevation range. These results, in addition to other data collected in this watershed, suggest that nonhabitat-related stressors (e.g., accidental chemical spills) also have significant effects on biota in this basin. The number of cooccurring human land uses was inversely related to fish IBI (r ) -0.49, p < 0.01). Sites with g2 co-occurring land uses had >90% probability of having <2 mussel species present. Our findings predict that many mussel concentration sites are vulnerable to future extirpation. In addition, our results suggest that protection and enhancement of naturally vegetated riparian corridors, better controls of mine effluents and urban runoff, and increased safeguards against accidental chemical spills, as well as reintroduction or augmentation of threatened and endangered species, may help sustain native fish and mussel populations in this watershed.

Conducting Ecological Risk Assessments of Inorganic Metals and Metalloids: Current Status

“…The importance of WOE in ERA is expected to increase as ERAs expand to the determination of watershed-level risks (Diamond and Serveiss 2001;Obery and Landis 2002;Serveiss 2002), considering chemical, physical and biological stressors.…”

Urban environments as habitats for rare aquatic species: The case of leeches (Euhirudinea, Clitellata) in Warsaw freshwaters

“…Reduced diversity in terrestrial and aquatic urban habitats, as compared with agricultural or forestry neighborhood areas, has appeared in numerous studies: on vertebrates (Melles et al 2003;Mahan and O'Connell 2005;Luniak 2008), estuarine benthos (Pagliosa and Rodrigues Barbosa 2006) and on lotic invertebrates (Diamond and Serveiss 2001;Moore and Palmer 2005;Smith and Lamp 2008). Freshwater habitats situated in urban areas are particularly endangered by various types of human activity.…”

A Phased Approach for Assessing Combined Effects from Multiple Stressors

“…Multiple and logistic regressions can be used to identify the relative contributions of multiple stressors to observed effects, and the resulting equations can be used to predict combined effects. Diamond and Serveiss (2001) and Potter et al (2004) have used regression equations to examine the explanatory power of variables in watersheds. Norton et al (2002) used principal components analysis to evaluate the relative importance of 18 stressors, then used the first six stressor factors (various combinations of the original 18) within a multiple regression model.…”