Citation:

Weaver, P., J. Lazorchak, R. Herrmann, S. Decelles, G. Israel, A. Kascak, S. Goodrich, J. Rhodus, AND M. Griffith. Standardization of Acute and Short-term Chronic Methods for Whole Effluent and Receiving Water Toxicity Using the Mayfly, Neocloeon triangulifer. 2023 SETAC North America Annual Conference, Louisville, KY, November 12 - 16, 2023.

Impact/Purpose:

Whole Effluent Toxicity (WET) test methods for measuring the toxicity of effluents and receiving waters are found in 40 CFR Part 136. Short-term chronic freshwater toxicity test methods include the use of three species – a cladoceran (Ceriodaphnia. dubia), the fathead minnow (Pimephales promelas), and a green alga (Selenastrum capricornutum, now known as Raphidocelis subcapitata). Acute freshwater toxicity test methods include the use of several cladocerans (Daphnia magna, Daphnia pulex, and C. dubia) and freshwater fish (P. promelas, Cyprinella leedsi, Oncorhynchus mykiss, and Salvelinus fontinalis). The regulations include no representatives from the sensitive aquatic insect orders used extensively in water quality stream assessments. This research focuses on standardization of new culture, acute & short-term chronic methods that can be used in the Whole Effluent Toxicity (WET) NPDES program and to detect known and unknown chemical contaminants in reclaimed or produced waters in support of OW, Regional, State and utility needs using an aquatic insect model. This will help bridge the gap between toxicological testing of water quality and biological characterizations of stream water quality assessments.

Description:

Whole Effluent Toxicity (WET) test methods for measuring the toxicity of effluents and receiving waters are found in 40 CFR Part 136. Short-term chronic freshwater toxicity test methods include the use of three species – a cladoceran (Ceriodaphnia. dubia), the fathead minnow (Pimephales promelas), and a green alga (Selenastrum capricornutum, now known as Raphidocelis subcapitata). Acute freshwater toxicity test methods include the use of several cladocerans (Daphnia magna, Daphnia pulex, and C. dubia) and freshwater fish (P. promelas, Cyprinella leedsi, Oncorhynchus mykiss, and Salvelinus fontinalis). The regulations include no representatives from the sensitive aquatic insect orders used extensively in water quality stream assessments. In 2015, the results of an EPA study were published, establishing 48-hour acute and 14-day chronic test methods for Centroptilum triangulifer and comparing its sensitivity to two model invertebrates, C. dubia and D. magna. Mortality and growth effects were determined using the reference toxicants sodium chloride, potassium chloride, and copper sulfate. Since that time, there have been several papers and presentations about the use of those methods with Neocloeon triangulifer (formerly C. triangulifer). Currently, EPA is working on standardizing a 48-,72-, or 96-hour acute test method and a 7- to 10-day short-term chronic test method to determine mortality and growth effects of three reference toxicants (zinc sulfate, ammonia chloride, and diazinon) on N. triangulifer. Standardization of N. triangulifer culturing conditions including reformulated water and a defined diet of two diatoms, Mayamaea atomus and Nitzschia cf. pusilla, is currently under development. Percent survival and fecundity criteria, using pre-egg laying adult weights and egg hatch rates, are being developed for assessing overall culture fitness. Diatom food quality is being standardized through fatty acid lipid profiles, dry weight, and chlorophyll spectrometry for both culture and toxicological testing. The standardization of the acute and short-term chronic WET test methods and culture criteria for N. triangulifer will provide a new tool for use in detecting both known and unknown chemical and biological contaminants in wastewater and in ambient water quality testing for aquatic life protection. The progress and results of culture and test method development will be presented.

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