Response of predatory zooplankton populations to the experimental acidification of Little Rock Lake, Wisconsin

Technical Report · Fri Jan 01 04:00:00 EST 1993

OSTI ID:5696471

Sierszen, M E; Frost, T M

To assess the effects of lake acidification on large predatory zooplankton, the authors 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 three levels: pH 5.6, 5.2 and 4.7). Concentrations 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. In contrast, Epischura lacustris and Leptodora kindtii disappeared from limnetic samples, and water mites declined to near zero upon acidification. Treatment basin populations of E. lacustris declined sharply during the second year of acidification. The nature of the decline suggested sensitivity of an early life stage during the first year at pH 5.6. Leptodora kindtii showed no population response at pH 5.6, but declined to essentially zero at pH 5.2. Treatment basin populations of water mites fluctuated until declining in the fifth and sixth years (pH 4.7). These changes indicate a variety of direct and indirect responses to lake acidification.

• Research Organization: Environmental Protection Agency, Duluth, MN (United States). Environmental Research Lab.
• OSTI ID: 5696471
• Report Number(s): PB-94-101730/XAB; EPA--600/J-93/422
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
540350* -- Environment
Aquatic-- Site Resource & Use Studies-- (1990-)
ACID RAIN
ACIDIFICATION
ANIMALS
AQUATIC ORGANISMS
ARACHNIDS
ARTHROPODS
ATMOSPHERIC PRECIPITATIONS
BIODEGRADATION
BIOLOGICAL EFFECTS
CHEMICAL REACTIONS
DECOMPOSITION
DEVELOPED COUNTRIES
DIPTERA
INSECTS
INVERTEBRATES
LAKES
MITES
NORTH AMERICA
PH VALUE
PLANKTON
POPULATIONS
RAIN
SAMPLING
SURFACE WATERS
USA
WISCONSIN
ZOOPLANKTON