Contrasting effects of chloride on growth, reproduction, and toxicant sensitivity in two genetically distinct strains ofHyalella azteca

Abstract

The strain of Hyalella azteca (Saussure: Amphipoda) commonly used for aquatic toxicity testing in the United States has been shown to perform poorly in some standardized reconstituted waters frequently used for other test species. In 10-d and 42-d experiments, the growth and reproduction of the US laboratory strain of H. azteca was shown to vary strongly with chloride concentration in the test water, with declining performance observed below 15 mg/L to 20 mg/L. In contrast to the chloride-dependent performance of the US laboratory strain of H. azteca, growth of a genetically distinct strain of H. azteca obtained from an Environment Canada laboratory in Burlington, Ontario, Canada, was not influenced by chloride concentration. In acute toxicity tests with the US laboratory strain of H. azteca, the acute toxicity of sodium nitrate increased with decreasing chloride in a pattern similar not only to that observed for control growth, but also to previous acute toxicity testing with sodium sulfate. Subsequent testing with the Burlington strain showed no significant relationship between chloride concentration and the acute toxicity of sodium nitrate or sodium sulfate. These findings suggest that the chloride-dependent toxicity shown for the US laboratory strain may be an unusual feature of that strain and perhaps not broadly representative of aquatic organisms as a whole.

The evaluation of 3 diets for rearingHyalella aztecaand the influence of diet on acute ammonia toxicity

“…The chloride concentrations in the culture water in the present study were well above 15 mg/L (Supplemental Data, Table S3) and should not have been a limiting factor on the reproduction rates seen. The EC0 values, defined as the minimum chloride concentration resulting in maximum performance in 42 d testing, were found to be 10.54 mg Cl/L (CI 7.5–14.81) for growth and 19.16 mg Cl/L (CI 7.99–45.96), for reproduction, both below the values in the present study .…”

Selection of food combinations to optimize survival, growth, and reproduction of the amphipod Hyalella azteca in static‐renewal, water‐only laboratory exposures

“…The Borgmann water had nominal chloride and bromide concentrations of 73 mg/L and 0.8 mg/L, respectively, whereas the Duluth 100 water had concentrations of 28 mg/L and 0.04 mg/L, respectively. These ions have been shown to strongly influence performance of the US Lab strain of H. azteca (see Ivey and Ingersoll , this issue; and Soucek et al ), but in both cases it was determined that so long as a minimum concentration was present (15–20 mg Cl/L and 0.02 mg Br/L), further increasing the concentration of Cl or Br was not expected to improve survival, growth, reproduction, or response to toxicants. Therefore, the difference between the 2 waters used in the present study is not expected to confound responses to different food types.…”

“…At a USEPA-sponsored conference (Workshop on Advancing Methods for Culture and Toxicity Testing with the Amphipod Hyalella azteca, March 2-3, 2010, Chicago, IL), a host of culturing and testing inconsistencies among laboratories, particularly concerning food and water type used in culturing and testing, were brought to light. Studies investigating water quality effects, particularly the bromide and chloride dependence of this particular strain of H. azteca, are published in this issue (see Ivey and Ingersoll [14]) and previously [15]. The goals of the present study and a companion study by Hockett et al [16] (this issue) were to investigate how diets can be altered to improve performance of this species under staticrenewal and flow-through conditions, respectively.…”

Influence of dilution water ionic composition on acute major ion toxicity to the mayfly Neocloeon triangulifer

“…at a lower hardness (∼69 mg/L), confirming the sensitivity of mayflies to Na 2 SO 4 . There is a published data point at a similar hardness for H. azteca of 512 mg SO 4 /L (Soucek and Kennedy ), but the dilution water for that toxicity test had a chloride concentration lower than that considered sufficient for optimal health for that species (Soucek et al ). Thus, in general, N. triangulifer appears to be relatively sensitive to sodium salts, especially sodium sulfate.…”