10.1021/acs.est.6b05179.s001 Tamzin A. Blewett Tamzin A. Blewett Perrine L. M. DelompreĢ Perrine L. M. DelompreĢ Yuhe He Yuhe He Erik J. Folkerts Erik J. Folkerts Shannon L. Flynn Shannon L. Flynn Daniel S. Alessi Daniel S. Alessi Greg G. Goss Greg G. Goss Sublethal and Reproductive Effects of Acute and Chronic Exposure to Flowback and Produced Water from Hydraulic Fracturing on the Water Flea <i>Daphnia magna</i> American Chemical Society 2017 LC 50 value PCR LC 50 FPW toxicity Water Flea Daphnia magna Hydraulic crustacean Daphnia magna genes encoding xenobiotic metabolism 2017-01-31 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Sublethal_and_Reproductive_Effects_of_Acute_and_Chronic_Exposure_to_Flowback_and_Produced_Water_from_Hydraulic_Fracturing_on_the_Water_Flea_i_Daphnia_magna_i_/4645453 Hydraulic fracturing is an industrial process allowing for the extraction of gas or oil. To fracture the rocks, a proprietary mix of chemicals is injected under high pressure, which later returns to the surface as flowback and produced water (FPW). FPW is a complex chemical mixture consisting of trace metals, organic compounds, and often, high levels of salts. FPW toxicity to the model freshwater crustacean <i>Daphnia magna</i> was characterized utilizing acute (48 h median lethal concentrations; LC<sub>50</sub>) and chronic (21 day) exposures. A decrease in reproduction was observed, with a mean value of 18.5 neonates produced per replicate over a 21 day chronic exposure to 0.04% FPW, which was a significant decrease from the average of 64 neonates produced in the controls. The time to first brood was delayed in the highest FPW (0.04%) treatment. Neonates exhibited an LC<sub>50</sub> of 0.19% of full-strength FPW, making them more sensitive than adults, which displayed an LC<sub>50</sub> value of 0.75%. Quantitative PCR highlighted significant changes in expression of genes encoding xenobiotic metabolism (<i>cyp4</i>) and moulting (<i>cut</i>). This study is the first to characterize chronic FPW toxicity and will help with the development of environmental monitoring and risk assessment of FPW spills.