Rotifer population dynamics and food limitation in Little Rock Lake, Wisconsin
K. cochlearis and K. taurocephala populations showed a consistent pattern during a 4-year study period in Little Rock Lake. Their populations exhibited spring peaks followed by strong summer declines. The egg ratios and epilimnetic chloropyll showed a similar patterns. I hypothesized that population declines were caused by food limitations. Food addition experiments in small enclosures indicated that food was limiting when rotifer populations were declining. But food limitation was not evident during other times of the year. In addition, K. cochlearis and !· taurocephala showed a response to the acidification of Little Rock Lake during 1985 and 1987. Populations of K. cochlearis decreased in the acidified basin relative to the treatment basin after the acidification of 1985. While K. taurocephala increased substantially after 1985 and 1987 acidifications. Calculations of populations parameters indicated a statistically significant decrease in the birth rate of K. cochlearis in the acidified basin. These observations suggested that food limitation occurred for K. cochlearis in the acidified basin. However the results of food addition experiments indicated that the decline of K. cochlearis in the acidified basin could not be attributed to food limitation.