Sviluppo di reti trofiche della comunità planctonica per caratterizzare lo stato di salute dell'ecosistema marino

Plankton is the basis of the marine trophic web, but it is often difficult to obtain accurate data on interaction and metabolic parameters. For this reason, a newly developed approach is presented. It allows the integration of both ordinal qualitative and quantitative data. Using a Monte Carlo approach, realistic values within the parameter ranges are randomly selected to obtain several realistic food webs with a posteriori checking. In this way, it is possible to observe the resulting parameter distribution and perform statistical tests. This approach was applied to several sites in the Atlantic, and notably the planktonic food webs of the Venice Lagoon and Bermuda. Several uncertainty intervals were applied to metabolic parameters and diets of Atlantic food webs, and after applying whole system indicators, the results of the new approach were compared with the respective original study. The original studies lie in the middle of the distribution of the ensemble of the obtained food webs when the whole system indicators are based on metabolic parameters only, and outside the distribution when they are also based on diet. The new approach was applied to the food webs of the Venice lagoon in July of two different years. Detritus resuspension was a pressure perturbation of the system that increased its resilience at the expense of its efficiency. The approach was also applied to a 26-year time series at the Bermuda site. Despite the decline in phytoplankton biomass due to climate change, the plankton food web shows high resilience to perturbation, thanks to various trophic strategies such as detritivory and mixotrophy. Plankton food webs are therefore a useful tool for analyzing the health of the whole ecosystem and for making predictions.