Vertical distribution of planktonic rotifers in a karstic meromictic lake

摘要: Vertical distribution of planktonic rotifers is described in relation to temperature and oxygen Lake La Cruz, a single-doline, closed karstic lake (121 m diameter 25 maximum depth) which shows iron meromixis. Samples were taken by peristaltic pumping at 10 cm depth intervals the oxycline zone from June 1987 September 1988. A model rotifer vertical structure stratified lakes proposed. Rotifers concentrate their populations depths with intense gradients. As stratification develops some show downward migration following thermocline others an upward oxycline. The production-respiration balance lake, so position respect layer production, depends on meteorological conditions. shift dominance congeneric or related species can occur consecutive years. In mixing conditions subterranean inflow spring much more 1988 than 1987, distance between production decomposition was smaller Anuraeopsis miraclei, oxycline-bound high abundance displaced A. fissa fissa, metalimnetic during early summer, reached peak densities (3 × 104 ind l−1) oxycline, equaling miraclei preceeding year.