Cascade project at North Temperate Lakes LTER - Daily data for key variables in whole lake experiments on early warnings of critical transitions, Paul and Peter Lakes, 2008-2011

Peter Lake's food web was altered by adding largemouth bass at a slow rate while monitoring key food web constituents including littoral minnow abundance indexed as catch per trap per hour, zooplankton biomass, and concentration of chlorophyll a. Paul Lake was manipulated and the same variables were measured there. In Peter Lake, we expected littoral catch of minnows to first increase as minnows moved into the littoral zone due to the threat of bass predation and then decrease due to bass predation. We expected zooplankton biomass to increase as minnows moved into the littoral zone. We expected chlorophyll to decrease due to increased grazing by zooplankton. We expected that variance and autocorrelation of chlorophyll would increase as the food web passed a critical transition. We expected that the time series in Paul Lake would represent the normal variability of an unmanipulated lake彼得湖的食物网通过缓慢投放大口黑鲈（Largemouth Bass）进行调控，同时监测关键食物网组成要素，包括以每小时每诱捕器捕获量为量化指标的沿岸带鲦鱼丰度、浮游动物生物量及叶绿素a（Chlorophyll a）浓度。保罗湖同样开展了实验操纵，并同步测定了上述相同变量。 在彼得湖中，我们预期沿岸带鲦鱼的捕获量会先出现上升——因鲦鱼为躲避大口黑鲈的捕食而迁入沿岸带，随后因大口黑鲈的捕食压力而下降。我们预期随着鲦鱼迁入沿岸带，浮游动物生物量会随之升高；而浮游动物取食压力增加将导致叶绿素浓度下降。此外，我们预期当食物网跨越临界转变点时，叶绿素的时间序列方差与自相关性会显著上升。 我们预期保罗湖的时间序列将呈现未受操纵湖泊的正常波动特征。