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Growth and survivorship of the mayfly Centroptilum triangulifer (Ephemeroptera: Baetidae) exposed to elevated specific conductance in flow-through mesocosms
Citation:
JOHNSON, B. R., P. Weaver, K. Hammer, J. M. LAZORCHAK, AND D. Funk. Growth and survivorship of the mayfly Centroptilum triangulifer (Ephemeroptera: Baetidae) exposed to elevated specific conductance in flow-through mesocosms. Presented at Society for Freshwater Science Annual Meeting, Louisville, KY, May 20 - 24, 2012.
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
We tested sensitivity of a parthenogenetic mayfly, Centroptilum triangulifer, from a laboratory culture to excess conductivity created by adding NaCl and CaCl2 to natural stream water. Ions in these salts comprise approximately 95% of total dissolved solids in brine water produced from oil and gas wells. Eight indoor stream channels were dosed with salt stock to realize a conductivity gradient ranging from 359 (control) to 8884 uS cm-1. Sixty early instar C. triangulifer from the same egg clutch were measured and deployed in flow-through mesocosms plumbed to each channel for 20 d. Larval growth rate was significantly reduced at all concentrations above control. Adult emergence occurred only in the control chamber (58% of individuals). Significant mortality occurred at concentrations >2910 uS cm-1 with 100% mortality at the highest salt concentration. Calculated median lethal concentration was 2866 uS cm-1. We conclude that even slightly elevated conductivity can impair growth and development of this stream-dwelling mayfly. Further exposure testing of C. triangulifer will continue in effort to develop more representative model organisms for assessing impairment to stream populations.