title: Elevated major ion concentrations inhibit larval mayfly growth and development.
abstract: Anthropogenic disturbances, including those from developing energy resources, can alter stream chemistry significantly by elevating total dissolved solids. Field studies have indicated that mayflies (Order Ephemeroptera) are particularly sensitive to high total dissolved solids. In the present study, the authors measured 20-d growth and survivorship of larval Neocloeon triangulifer exposed to a gradient of brine salt (mixed NaCl and CaCl2 ) concentrations. Daily growth rates were reduced significantly in all salt concentrations above the control (363 µS cm(-1) ) and larvae in treatments with specific conductance >812 µS cm(-1) were in comparatively earlier developmental stages (instars) at the end of the experiment. Survivorship declined significantly when specific conductance was >1513 µS cm(-1) and the calculated 20-d 50% lethal concentration was 2866 µS cm(-1) . The present study's results provide strong experimental evidence that elevated ion concentrations similar to those observed in developing energy resources, such as oil and gas drilling or coal mining, can adversely affect sensitive aquatic insect species.
authors.affiliation: United States Environmental Protection Agency, National Exposure Research Laboratory, Cincinnati, Ohio.
authors.forename: Brent R
authors.initials: BR
authors.lastname: Johnson
authors.forename: Paul C
authors.initials: PC
authors.lastname: Weaver
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Nietch
authors.forename: James M
authors.initials: JM
authors.lastname: Lazorchak
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Struewing
authors.forename: David H
authors.initials: DH
authors.lastname: Funk
mesh_terms: D000818:Animals; D002122:Calcium Chloride / Q000032:analysis / Q000633:toxicity*; D065133:Ephemeroptera / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012965:Sodium Chloride / Q000032:analysis / Q000633:toxicity*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D002122:Calcium Chloride
keywords: Centroptilum; Conductivity; Neocloeon; Total dissolved solids; Toxicity