Fluctuations in fish populations in lakes can cascade through food webs to alter nutrient cycling, algal biomass and primary production. Trophic cascades may interact with nutrients and physical factors to explain most of the variance in lake ecosystem process rates. In this book, a multidisciplinary research team tests this idea by manipulating whole lakes experimentally, and coordinating this with palaeolimnological studies, simulation modelling, and small-scale enclosure experiments. Consequences of predator-prey interactions, behavioural responses of fishes, diel vertical migration of zooplankton, plankton community change, primary production, nutrient cycling and microbial processes are described. Palaeolimnological techniques enable the reconstruction of trophic interactions from past decades. Prospects for analysing the interaction of food web structure and nutrient input in lakes are explored.