An important role in this respect has been played by studies on crustacean zooplankton, because of their key, intermediate role, linking fast-reacting and fast-growing phytoplankton to upper levels of the food web exhibiting a delayed response to changes in climate. Pioneer studies, inspired by evidence from sea plankton (Taylor et al., 1992) and awareness that plankton succession in temperate lakes was strongly influenced by year-to-year variations in the weather (Reynolds, 1987), demonstrated that between-year variations in zooplankton biomass were closely correlated with meteo-climatic indices (namely, the latitude of the north wall of the Gulf Stream; George and Taylor, 1995). Successive research on meteoclimatic drivers of change in zooplankton have been mainly addressed to indices developen