Riscaldamento globale: exergia, trofodinamica e zooplancton

We report here the results of two studies on the impact of climate change, particularly of warming, carried out in a lake (Lake Maggiore) where eutrophication and re-oligotrophication were previously analyzed. These studies allow validation of the hypothesis that global warming would produce eutrophication-like effects on plankton communities. They also provide an opportunity to assess the relationship between climate warming and trophic status, and to verify that the climatic signal is more evident in remote sites because it is not overwhelmed by the nutrient enrichment signal, that predominates in eutrophic systems. In systems for which longterm data allow for the definition of a baseline situation, the impact of exceptional meteorological conditions can be assessed, using a "quasi-experimental" approach, comparable, as for results, to in situ experiments. The following annual response to ambient temperature was mediated by trophic dynamics, but was generally an increase in the efficiency of the food chaine one year following warming events. During an exceptionally warm year, however, only the eutrophication-like effect on zooplankton, was apparent, as the population phenology was substantially different from that detected in more productive years.