Planktonic organisms are considered good indicators of environmental changes, even more sensitive than abiotic variables per se. In relatively recent years, the importance of pluriannual plankton series has become increasingly important, also for management purposes and in the process of bridging the gap between environmental science and management policy. Plankton studies in Lake Maggiore date back to middle 1900s, although a regular monitoring started in late seventies, in the framework of an agreement between Swiss and Italian Governments. The full long-term data series (1981-2011) entirely covers the lake's recovery, since full mesotrophy of mid-1970s, to present oligotrophy. Response of plankton communities to eutrophication reversal after lake restoration included a gradual increase in the number of phytoplankton taxonomic units and in cell density along with a decrease of average cell size. Changes in taxonomic composition, population density and mean body size were also tracked in the zooplankton. Data we obtained through these studies, however, pertaining to each single level of biological organization, do not allow per se for highlighting quantitative changes in trophic relationships and in ecosystem functioning driven by changes in trophy. Environmental changes, such as those attributable to eutrophication/oligotrophication processes, as well as to climate, are expected to affect not only taxonomic composition of planktonic assemblages, but also the trophic relationships and the ecosystem processes. Moreover, during the lake's oligotrophication the role of climatic constraints became increasingly important in controlling plankton dynamics, affecting phytoplankton nutrient supply, resource ratio, population phenology and the whole life cycles of the organisms involved. Our aim is to track the ecosystem response by analysing the phytoplankton-zooplankton relationship from a functional point of view, trying to find the key driver across different steps of the lake's trophic history, in the attempt to disentangle climate- from trophy-related responses of lake ecosystems.
Eutrophication and recovery of the large and deep subalpine Lake Maggiore: patterns, trends and interactions of planktonic organisms between trophic and climatic forcings
Giuseppe Morabito;
2013
Abstract
Planktonic organisms are considered good indicators of environmental changes, even more sensitive than abiotic variables per se. In relatively recent years, the importance of pluriannual plankton series has become increasingly important, also for management purposes and in the process of bridging the gap between environmental science and management policy. Plankton studies in Lake Maggiore date back to middle 1900s, although a regular monitoring started in late seventies, in the framework of an agreement between Swiss and Italian Governments. The full long-term data series (1981-2011) entirely covers the lake's recovery, since full mesotrophy of mid-1970s, to present oligotrophy. Response of plankton communities to eutrophication reversal after lake restoration included a gradual increase in the number of phytoplankton taxonomic units and in cell density along with a decrease of average cell size. Changes in taxonomic composition, population density and mean body size were also tracked in the zooplankton. Data we obtained through these studies, however, pertaining to each single level of biological organization, do not allow per se for highlighting quantitative changes in trophic relationships and in ecosystem functioning driven by changes in trophy. Environmental changes, such as those attributable to eutrophication/oligotrophication processes, as well as to climate, are expected to affect not only taxonomic composition of planktonic assemblages, but also the trophic relationships and the ecosystem processes. Moreover, during the lake's oligotrophication the role of climatic constraints became increasingly important in controlling plankton dynamics, affecting phytoplankton nutrient supply, resource ratio, population phenology and the whole life cycles of the organisms involved. Our aim is to track the ecosystem response by analysing the phytoplankton-zooplankton relationship from a functional point of view, trying to find the key driver across different steps of the lake's trophic history, in the attempt to disentangle climate- from trophy-related responses of lake ecosystems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
