Effects of wastewater treatment plant effluents on freshwater mollusks in the upper Clinch River, Virginia, USA

Abstract

Field and laboratory studies were conducted to determine mollusk distributions in proximity to wastewater treatment plants (WTP's) in the upper Clinch River and to test the tolerance of two mollusk species to monochloramine and unionized ammonia, the major toxicants in domestic effluent. River reaches up to 3.7 km downstream of WTP's were devoid of freshwater mussels (Unionidae), and tolerance to effluents varied among snails, sphaeriid clams, and the asian clam CorbiculaJEuminea. Residential communities with septic systems had no measurable impact on mollusk assemblages downstream.Laboratory bioassays with glochidia of Villosa iris yielded the following results: 24 h EC,, and LC,, values of 0.042 mg l-' and 0.084 mg l-' monochloramine, respectively; and 24 h EC& and LC,, of 0.237 mg 1-l and 0.284 mg l-' unionized ammonia, respectively. Glochidia rank among the most sensitive invertebrates in their tolerance to these toxicants. The snail Pleurocera unciale unciale was moderately sensitive, with 96 h LC,, values of 0.252 mg l-' monochloramine and 0.742 mg l-' unionized ammonia. Monitoring of monochloramine and unionized ammonia concentrations 0.1 km below WTP outfalls indicated that monochloramine was the toxicant likely inhibiting mollusk recovery below these plants.

Urbanization Effects on Watershed Hydrology and In-Stream Processes in the Southern United States

“…Movement of anthropogenic nutrients into the food web was also documented in headwater streams in the Piedmont of NC [170,171]. In VA, freshwater mussels were absent below a wastewater treatment plant, most likely due to sensitivity to the domestic effluent; however, snails and clams were more tolerant [172]. As wastewater treatment plants are often embedded in the urban landscape, it can be difficult to tease apart the most significant factor causing reduced ecosystem health.…”

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

“…Several lines of evidence point to the importance of various land use activities and riparian corridor integrity as determinants of native mussel and fish distribution in the Clinch and Powell River Basin with proximity to coal mining operations having the most adverse effects. Site-specific factors that could have also contributed to effects on IBI and mussel species richness are wastewater discharge and other point and nonpoint sources that could release toxic constituents or excessive nutrients downstream (47). Many of these were not explicitly included in our analyses due to a lack of appropriate data.…”

Influence of urban tributaries on freshwater mussel populations in a biologically diverse piedmont (USA) stream

“…They reported that unionids were often absent from large (*4 km) reaches below wastewater treatment facilities. Based on laboratory toxicity assays, Goudreau et al (1993) hypothesized that glochidial sensitivity to monochloroamine and unionized ammonia may be responsible for mussel extirpations downstream of wastewater outflows.…”

“…They found that although physicochemical conditions were not acutely toxic to mussels, large sections of the study river were devoid of mussels downstream of the effluent discharge. Goudreau et al (1993) examined effects of wastewater discharge on mollusk assemblages in the Clinch River in Virginia, USA. They reported that unionids were often absent from large (*4 km) reaches below wastewater treatment facilities.…”