Climate change and artificial barrier effects on the Venice Lagoon: Inundation dynamics of salt marshes and implications for halophytes distribution

Transitional areas such as lagoons are among the most impacted and delicate environments, threatened by the combined effects of climate change and human action. The integrated management of these specific systems would require the possibility to investigate and cope with induced changes in the hydrodynamics, morphodynamics and ecosystem characteristics.The main goal of the present work is to examine, by means of a modeling tool, the effects of the combined action of sea level rise, climate changes and human activities, such as the building of structures for coastal defense (mobile barriers), on transitional area habitats.The finite element coastal model SHYFEM was applied on the Venice Lagoon, which fully represents the example of a natural-anthropogenic environment, due to the continuous action of humans in changing it for preservation. The model was forced by a regional downscaling from a global climate atmospheric model, simulating both the control century (1960-1990) and three periods (2010-2039, 2040-2069, 2070-2100) of the Intergovernmental Panel for Climate Change (IPCC) A1B scenario that corresponds to a very rapid economic and demographic growth combined with the introduction of more efficient technologies. A relation on the interaction between salt marshes inundation and growth and salt marshes halophytes distribution was discussed. Results: showed a tendency of the system to marine physical characteristics, in terms of an increase in salinity. The hypothetic increase of sea level tends to produce a decrease of areas like salt marshes, up to a total extinction for the most extreme scenario. The modeling results identified the correlation of halophytes growth and specific physical conditions of the environment (salinity, exposure time, soil depth respect to mean sea level), leading to the preliminary conclusion that the halophyte more resilient to the increase of flooding and of salinity (Salicornia veneta) would be the only one present in the future. The modeling implementation allowed the investigation of the whole lagoon, providing an hypothesis of the evolution of halophytes population in future scenarios and a precious tool also for the integrated management of these typologies of environment, in a climate change perspective. © 2014 Elsevier Ltd.