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A Mesoscale Total Dissolved Solids Quantity and Quality Study Integrating Responses of Multiple Biological Components in Small Stream Communities
Citation:
Nietch, C., Jim Lazorchak, B. Johnson, D. Brown, B. Ramakrishnan, H. Rogers, P. Weaver, D. Macke, Joel Allen, K. Daniels, S. Decelles, AND K. Patnode. A Mesoscale Total Dissolved Solids Quantity and Quality Study Integrating Responses of Multiple Biological Components in Small Stream Communities. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, November 11 - 15, 2012.
Impact/Purpose:
Determine stream community-level consequences of an excess TDS dosing gradient supporting the re-evalution of water quality TDS criteria underway by States in Regions 3 and 5.
Description:
A 42-day dosing test with ions comprising an excess TDS was run using mesocosms colonized with natural stream water fed continuously. In gridded gravel beds biota from microbes through macroinvertebrates are measured and interact in a manner realistic of stream riffle/run ecology. Single species assays were run in-parallel using the equivalent mesocosm matrices. Although the species assemblage and background water chemistries of the mesocosms may not translate to certain field locations, the intent was to study the potential change in the ecologies of community interactions. Paired with the single-species assays the approach provides community context to standard toxicological tests. The excess TDS was comprised of Cl-, Na+, and Ca2+, which are the primary ions making-up produced waters of Central Appalachian shale brines. The realized TDS concentrations were 247, 370, 590, 742, 1288, 2066, 3615, and 6963 (mg/l). Targets were based on mixing-models from fifty Pennsylvania oil and gas wastewater permits and estimated low flows of their receiving streams. An increasing trend in periphytic algal biomass happened across doses higher than 590 mg/l. Visible differences in algal community structure occurred after 742 mg/l including a shift to a high percentage of red alga (Compsopogon) coverage, increased density of long-chain diatom filaments, and a decrease in cyanobacteria colonies. These changes coincided with community changes that were significant after the 1288 mg/l dose for macroinvertebrates colonizing the mesocosms. Chironomids and Elmidae were the primary larval insects. They responded oppositely to the excess TDS with a respective increase and decrease in doses higher than 2066 mg/l. EPT taxa (only 3% of individuals) generally decreased with increasing TDS. Polycentropid caddisfly nets were absent in the two highest doses. Worms and crustaceans exhibited negative dose-responses, while snails appeared unaffected. Interpreting the single-species exposures were more straightforward. They suggested significant (LC50) lethality near the 2066 mg/l TDS dose for two species of mussels and daphnids, while a mayfly exhibited higher sensitivity. All endpoints considered, the data suggested that a chronic dose of greater than 590 mg/l could start to alter the producers in streams, while varied responses in the consumers have significant community-wide consequence at exposures greater than 1288 mg/l and when the TDS is dominated by Cl-, Na+, and Ca2+ ions.
