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Standardization of a short-term chronic method using Daphnia magna
Citation:
Glimsdal, L., W. Backe, R. Hockett, C. Jenson, A. Johnson, S. Kadlec, A. Kascak, Jim Lazorchak, Dave Mount, AND T. Norberg-King. Standardization of a short-term chronic method using Daphnia magna. SETAC, Pittsburgh, PA, November 13 - 17, 2022. https://doi.org/10.23645/epacomptox.21424503
Impact/Purpose:
This presentation will summarize the work in progress in ORD’s Cincinnati, OH and Duluth, MN laboratories to optimize and validate the performance of a 4-d Daphnia magna static-renewal survival and growth test. This test method may be an alternative for National Discharge Elimination System permitting and other risk assessments. The Office of Water has expressed interest in it and has provided guidance on its development. Early results suggest this test method had consistent performance between laboratories, among replicate tests, and compared with 7-d chronic Ceriodaphnia dubia tests. Our intended audience is ecotoxicologists and risk assessors from government, industry, and academia at an international professional conference. This work is taking place under the Safe and Sustainable Water Resources National Program. Specifically, it is occurring under SSWR 9.1.1
Description:
A few years ago, US EPA’s Office of Research and Development (ORD) Cincinnati, OH laboratory published a 4-d Daphnia magna static-renewal survival and growth test beginning with <8 h-old neonates (Lazorchak et al. 2009). This method could be another short-term test with utility in the National Discharge Elimination System permitting process for whole effluent toxicity testing and in other risk assessments. Two ORD laboratories (Duluth, MN; Cincinnati, OH) have conducted additional 4-d studies to optimize method performance, followed by standardization studies to evaluate method variability and reproducibility using reference toxicants. The standardization study consists of triplicate tests conducted in parallel by both laboratories, with each of three toxicants: ammonia, zinc, and diazinon. Each toxicant is also tested using a 7-d chronic Ceriodaphnia dubia test for comparison. For ammonia, intra-laboratory variation in IC25 values for weight was relatively low (CV = 20%, 27%), but there was an apparent difference in toxicant sensitivity between laboratories, with IC25 values of 24 to 33 mg/L as N for Duluth, and from 50 to 87 mg/L as N for Cincinnati. Reasons for the difference in apparent sensitivity are under investigation, and include differences in test solution pH and in algal food preparation. Coefficient of variation among replicates in control treatments has been low (range 1.4 to 5.4%), and percent minimum significant difference for means comparisons has averaged 9.7% (range 4.65 to 18.24%). A post hoc power analysis will be used to quantify the relationship between number of replicate exposure chambers and statistical power to detect differences between experimental treatments. Future method standardization work will include evaluation of whole effluents with both species. The views expressed in this presentation are those of the authors and do not necessarily reflect the views or policies of the United States Environmental Protection Agency.
URLs/Downloads:
DOI: Standardization of a short-term chronic method using Daphnia magna
GLIMSDAL ET AL. SETAC 2022 POSTER DRAFT 101222.PDF (PDF, NA pp, 755.835 KB, about PDF)