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RESPONSE OF PREDATORY ZOOPLANKTON POPULATIONS TO THE EXPERIMENTAL ACIDIFICATION OF LITTLE ROCK LAKE, WI
Citation:
Sierszen, M. AND T. Frost. RESPONSE OF PREDATORY ZOOPLANKTON POPULATIONS TO THE EXPERIMENTAL ACIDIFICATION OF LITTLE ROCK LAKE, WI. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/422 (NTIS PB94101730), 1993.
Description:
To assess the effects of lake acidification on large predatory zooplankton, we monitored population levels of four limnetic taxa for 6 years in a lake with two basins, one of which was experimentally acidified (2 years at each of there levels: pH 5.6, 5.2, and 4.7). oncentrations of phantom midge (Chaoborus spp.), the most abundant large predator, remained similar in the treatment and reference basins until the fourth year (pH 5.2) when they increased in the treatment basin. n contrast, Epishura lacustris and Leptodora kindtii disappeared from limnetic samples, and water mites declined to near zero upon acidification. reatment basin populations of E. lacustris declined sharply during the second year of acidification. he nature of the decline suggested sensitivity of an early life stage during the first year at pH 5.6. eptodora kindtii showed no population response at pH 5.6, but declined to essentially zero at pH 5.2. reatment basis populations of water mites fluctuated until declining in the fifth and sixth years (pH 4.7). hese changes indicate a variety of direct and indirect responses to lake acidification.