A four decades multiparametric investigation in a Mediterranean dynamic ecosystem: Mollusc assemblages answer to the environmental changes

The ecosystem changes of "Marinello coastal lakes" - a brackish dynamic area located on the Tyrrhenian coast ofSicily (Italy) - have been examined through the analysis of the adaptive response of mollusc assemblages to thegeomorphological and environmental changes. In particular, we have contextually analysed the changes insalinity, mud and organic carbon together with mollusc abundance and distribution, comparing the data setsfrom several multidisciplinary investigations that we performed in about forty years.Our studies have evidenced that the space-time dynamics of the geomorphological, environmental and trophicparameters have led the progression of Marinello ecosystem, favoring the onset of transient windows of connectivity (TWCs) between different habitats. TWCs, by supporting continuous re-arrangements of mollusc populations, have contributed to increase the functional and ecological complexity of the system. Salinity inparticular has proven to be the most affecting factor on the diversification of mollusc assemblages, explaining63% and 44% of variation for brackish and marine species respectively. In addition, the distribution of bothdetritus and suspension feeders has been mostly affected by salinity.The interannual analysis of the mollusc assemblages has shown in the whole system a generalised increase inthe number of species, likewise, also the species richness recorded in each basin generally increased with thetime. Metapopulations in the Marinello ecosystem have shown to be related to significant modifications in thehabitat patches, in turn connected to the anthropogenic interventions or to the geomorphological progression ofthe entire physiographic system.Significant relationships among biotic and abiotic parameters have highlighted important implications on theecosystem functioning, suggesting their possible application in the improvement of investigation tools for thetransitional environments.