Using an interlaboratory study to revise methods for conducting 10‐d to 42‐d water or sediment toxicity tests with Hyalella azteca

Abstract

Studies have been conducted to refine US Environmental Protection Agency, ASTM International, and Environment Canada standard methods for conducting 42-d reproduction tests with Hyalella azteca in water or in sediment. Modifications to the H. azteca method include better-defined ionic composition requirements for exposure water (i.e., >15 mg/L of chloride and >0.02 mg/L of bromide) and improved survival, growth, and reproduction with alternate diets provided as increased rations over time in water-only or whole-sediment toxicity tests. A total of 24 laboratories volunteered to participate in the present interlaboratory study evaluating the performance of H. azteca in 42-d studies in control sand or control sediment using the refined methods. Improved growth and reproduction of H. azteca was observed with 2 alternate diets of 1) ramped diatoms (Thalassiosira weissflogii) + ramped Tetramin or 2) yeast-cerophyll-trout chow (YCT) + ramped Tetramin, especially when compared with results from the traditional diet of 1.8 mg YCT/d. Laboratories were able to meet proposed test acceptability criteria and in most cases had lower variation in growth or reproduction compared with previous interlaboratory studies using the traditional YCT diet. Laboratory success in conducting 42-d H. azteca exposures benefited from adherence to several key requirements of the detailed testing, culturing, and handling methods. Results from the present interlaboratory study are being used to help revise standard methods for conducting 10-d to 42-d water or sediment toxicity exposures with H. azteca. Environ Toxicol Chem 2016;35:2439-2447. © 2016 SETAC.

Acute and chronic toxicity of aluminum to a unionid mussel (Lampsilis siliquoidea) and an amphipod (Hyalella azteca) in water‐only exposures

“…Mussels were not fed during the acute exposure, whereas amphipods were fed 0.25 mg of diatoms and 0.5 mg of TetraMin once daily as recommended by ASTM International [24,25] and Ivey et al [27]. Eight beakers per concentration were placed in the diluter, 4 replicate beakers for the mussel test and the other 4 replicate beakers for the amphipod test.…”

“…The control survival met the chronic mussel test acceptability criterion of control survival of !80% [24]. The control survival of amphipods was 95%, and control dry weight of amphipods was 0.45 mg/individual, meeting the chronic amphipod test acceptability criterion of control survival of !80% and dry weight of 0.35 mg/individual [25,27]. There were no significant differences in mean survival between the control and any treatment of both species; however, mean dry weight was significantly reduced starting in the 300 mg/L treatment for mussels and in the 600 mg/ L treatment for amphipods ( Table 2).…”

Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters

“…Performance of H. azteca was evaluated relative to proposed test acceptability criteria for revisions being considered to ASTM International and USEPA for conducting 42‐d water or sediment exposures with H. azteca tested with 2 new diet rations and with water quality requirements of >15 mg Cl/L and >0.020 mg Br/L . Specifically, the test acceptability criteria were established as 10‐d, 28‐d, and 42‐d survival >80%; 10‐d dry weight >0.050 mg/individual; 28‐d dry weight >0.35 mg/individual; 42‐d dry weight >0.50 mg/individual; and 42‐d young/surviving female >6.0 (Supplemental Data, Table S1).…”

“…Colors indicate test water: orange = Smith reconstituted water; gray = Borgmann reconstituted water; cyan = 100 well water; black = 300 well water. The horizontal line is the 6.0 young/female proposed test acceptability criterion , and the vertical line is the 0.50 mg/individual 42‐d weight test acceptability criterion. Symbols with a red border indicate bromide concentrations <0.020 mg/L.…”

Validation of a new standardized test method for the freshwater amphipod Hyalella azteca: Determining the chronic effects of silver in sediment

“…Control organisms in clean sediment grew to an average of 0.762 mg/organism dry weight, indicating that test conditions were suitable to maintain organisms over the 42‐d exposure (i.e., >0.5 mg/organism dry wt in 42 d as proposed as the minimum growth test acceptability criterion for the revised USEPA method ). Final dry weight was significantly greater at the highest sediment Ag concentration (2088 mg/kg dry wt; Figure ); however, this increase was likely attributed to the enhanced food supply per surviving individual.…”