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COMMUNITY SCALE STREAM TAXA SENSITIVITIES TO DIFFERENT COMPOSITIONS OF EXCESS TOTAL DISSOLVED SOLIDS
Nietch, C., Jim Lazorchak, B. Johnson, Joel Allen, AND P. Weaver. COMMUNITY SCALE STREAM TAXA SENSITIVITIES TO DIFFERENT COMPOSITIONS OF EXCESS TOTAL DISSOLVED SOLIDS. Presented at Joint Aquatc Sciences Meeting, Portland, OR, May 18 - 23, 2014.
Supports the development of excess TDS criteria for aquatic life criteria
Model stream chronic dosing studies (42 d) were conducted with three total dissolved solids (TDS) recipes. The recipes differed in composition of major ions. Community scale emergence was compared with single-species responses conducted simultaneously using the whole effluent toxicity (WET) testing format and a new ex-situ exposure. The mayfly, Centroptilum triangulifer (Ephemeroptera:Baetidae), tested in the WET format was more sensitive to excess TDS regardless of its composition than other standard test organisms, and its sensitivity tended to decrease in the ex-situ format, where the response reflected that of Ephemeroptera (E) emergence at the community scale. Trichoptera (T) emergence was equally as sensitive as E, except when the TDS was dominated by salts of Cl-, which T was less sensitive to. Compared to E and T, Chironomidae emergence was less sensitive when the TDS was dominated by Cl- salts and NaHCO3-, but more sensitive when the TDS was a mixture of SO42- salts and HCO3-. The E and T sensitivities would not be protected by existing State-level TDS water quality targets, suggesting reconsideration of TDS criteria is warranted.