Abstract
Abstract Freshly fertilized eggs of walleye Stizostedion vitreum were incubated in the outlet waters of George Lake (pH 5.4) and sections of a nearby stream (pH 6.0, 6.6). Ten-day bioassays with yolk-sac larvae of rainbow trout Salmo gairdneri were run concurrently at the walleye sites and at additional sites with low pH (4.6) and with humic water (pH 5.5). Walleye egg mortality was low (25.5–33.5%) at pH 6.0. High mortality (90.5%) occurred between fertilization and the eyed-egg stage at the pH 5.4 site. Mortality of rainbow trout yolk-sac larvae approached 100% within 5 days at both pH 4.6 and 5.4. In contrast, total mortality was less than 3% at pH 6.0 and also in low-pH humic water (pH 5.5). The high mortality of walleye eggs in the acidic outlet waters of George Lake suggests that the acidification of this lake was responsible for the extinction of its walleye stock. The striking differences in mortality of rainbow trout yolk-sac larvae between sites of similar pH (5.4–5.5) indicated that H+-toxicity...
Published Version
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