title: Effect of diet quality on chronic toxicity of aqueous lead to the amphipod Hyalella azteca.
abstract: The authors investigated the chronic toxicity of aqueous Pb to the amphipod Hyalella azteca (Hyalella) in 42-d tests using 2 different diets: 1) the yeast + cereal leaf + trout pellet (YCT) diet, fed at the uniform low ration used in standard methods for sediment toxicity tests; and 2) a new diet of diatoms + TetraMin flakes (DT), fed at increasing rations over time, that has been optimized for use in Hyalella water-only tests. Test endpoints included survival, weight, biomass, fecundity, and total young. Lethal effects of Pb were similar for the DT and YCT tests (20% lethal concentration [LC20] = 13 μg/L and 15 μg/L, respectively, as filterable Pb). In contrast, weight and fecundity endpoints were not significantly affected in the DT test at Pb concentrations up to 63 µg/L, but these endpoints were significantly reduced by Pb in the YCT test-and in a 2005 test in the same laboratory with a diet of conditioned Rabbit Chow (RC-2005). The fecundity and total young endpoints from the YCT and RC-2005 tests were considered unreliable because fecundity in controls did not meet test acceptability criteria, but both of these tests still produced lower Pb effect concentrations (for weight or biomass) than the test with the DT diet. The lowest biotic ligand model-normalized effect concentrations for the 3 tests ranged from 3.7 μg/L (weight 20% effect concentration [EC20] for the RC-2005 test) to 8.2 μg/L (total young EC20 for the DT test), values that would rank Hyalella as the second or third most sensitive of 13 genera in a species sensitivity distribution for chronic Pb toxicity. These results demonstrate that toxicity tests with Hyalella fed optimal diets can meet more stringent test acceptability criteria for control performance, but suggest that results of these tests may underestimate sublethal toxic effects of Pb to Hyalella under suboptimal feeding regimes. Environ Toxicol Chem 2016;35:1825-1834. Published 2015 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and as such, is in the public domain in the United States of America.
authors.affiliation: US Geological Survey, Columbia, Missouri, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Besser
authors.affiliation: US Geological Survey, Columbia, Missouri, USA.
authors.forename: Chris D
authors.initials: CD
authors.lastname: Ivey
authors.affiliation: US Geological Survey, Columbia, Missouri, USA.
authors.forename: William G
authors.initials: WG
authors.lastname: Brumbaugh
authors.affiliation: US Geological Survey, Columbia, Missouri, USA.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Ingersoll
mesh_terms: D033304:Amphipoda / Q000187:drug effects* / Q000254:growth & development; D000818:Animals; D004032:Diet; D005298:Fertility / Q000187:drug effects; D007854:Lead / Q000032:analysis / Q000633:toxicity*; D013058:Mass Spectrometry; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D007854:Lead
keywords: Chronic test endpoints; Multiple stressors; Species sensitivity distribution; Test acceptability criteria