title: Comparing the effectiveness of chronic water column tests with the crustaceans Hyalella azteca (order: Amphipoda) and Ceriodaphnia dubia (order: Cladocera) in detecting toxicity of current-use insecticides.
abstract: Standard U.S. Environmental Protection Agency laboratory tests are used to monitor water column toxicity in U.S. surface waters. The water flea Ceriodaphnia dubia is among the most sensitive test species for detecting insecticide toxicity in freshwater environments.Its usefulness is limited, however, when water conductivity exceeds 2,000 µS/cm (approximately 1 ppt salinity) and test effectiveness is insufficient. Water column toxicity tests using the euryhaline amphipod Hyalella azteca could complement C. dubia tests; however, standard chronic protocols do not exist. The present study compares the effectiveness of two water column toxicity tests in detecting the toxicity of two organophosphate (OP) and two pyrethroid insecticides: the short-term chronic C. dubia test, which measures mortality and fecundity, and a 10-d H. azteca test, which measures mortality and growth. Sensitivity was evaluated by comparing effect data, and end point variability was evaluated by comparing minimum significant differences. Tests were performed in synthetic water and filtered ambient water to quantify the influence of water matrix on effect concentrations. The H. azteca test detected pyrethroid toxicity far more effectively, while the C. dubia test was more sensitive to OPs. Among endpoints, H. azteca mortality was most robust. The results demonstrate that the H. azteca test is preferable when conductivity of water samples is 2,000 to 10,000 µS/cm or if contaminants of concern include pyrethroid insecticides.
authors.affiliation: School of Veterinary Medicine, Department of Anatomy, Physiology, and Cell Biology, University of California, Davis, California, USA.
authors.forename: Linda A
authors.initials: LA
authors.lastname: Deanovic
authors.forename: Dan
authors.initials: D
authors.lastname: Markiewicz
authors.forename: Marie
authors.initials: M
authors.lastname: Stillway
authors.forename: Stephanie
authors.initials: S
authors.lastname: Fong
authors.forename: Inge
authors.initials: I
authors.lastname: Werner
mesh_terms: D033304:Amphipoda / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D033361:Cladocera / Q000187:drug effects* / Q000502:physiology; D004784:Environmental Monitoring / Q000379:methods; D007306:Insecticides / Q000633:toxicity*; D018570:Risk Assessment / Q000379:methods; D054712:Salinity; D018675:Toxicity Tests / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D007306:Insecticides; D014874:Water Pollutants, Chemical