KWRRI Research Reports


The effects of sulfuric acid on embryos, larvae, and juvenile fish were examined using standard bioassay techniques, as well as in a preference/ avoidance behavioral test. The objectives were to compare the sensitivities of the various ages of fish to acid and to assess the use of the behavioral test in a hazard assessment program. In an 8-day static renewal bioassay, embryos and larvae of the fathead minnow were not affected at a pH of 4.92 and above, but pH 3.57 produced complete mortality prior to hatching. In 96- hr acute bioassays, 8-wk juvenile fathead minnows survived 100% at pH's of 5.02 to 7.38, while complete mortality occurred at pH's below 3.90. At pH 4.29, only 15% of the population survived. Similar results were obtained with 12-wk animals. Juvenile bluegill sunfish (8 wk) and fathead minnows (6 and 14 wk) also were exposed to various concentrations of sulfuric acid in a preference/avoidance bioassay. Both 14-wk fathead minnows and 8-wk bluegill sunfish avoided acid pH's below pH 6.0, while the 6-wk fathead minnows avoided all acid levels tested (i.e., pH 6.19 and below). Therefore, the 6-wk fathead minnows appeared to be the most sensitive to acid stress. Based on these findings, juvenile fish, given a choice, would tend to avoid acid levels that might not prove lethal to them. Therefore, the preference/ avoidance bioassay should not be used alone but could be an important tool in evaluating sublethal effects in a multistage hazard assessment program.

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The work upon which this report is based was supported in part by funds provided by the United States Department of the Interior, Washington, D,C., as authorized by the Water Research Act of 1984. Public Law 98-242.