Sensitivity, Hazard, and Vulnerability of Farmlands to Saltwater Intrusion in Low-Lying Coastal Areas of Venice, Italy

Saltwater intrusion is a growing threat for coastal aquifers and agricultural practices in low-lying plains. Most of the farmlands located between the margin of the Southern Venice lagoon and the Northern Po delta, Italy, lie a few meters below mean sea level and are drained by a large network of artificial channels and hydraulic infrastructures to avoid frequent flooding and allow agricultural practices. This work proposes an assessment of the vulnerability to saltwater intrusion, following a new concept of the hazard status, resulting in combining the depth of the freshwater/saltwater interface and the electrical resistivity of the shallow subsoil. The sensitivity of the farmland system was assessed by using ground elevation, distance from freshwater and saltwater sources, permeability, potential runoff, land subsidence, and sea-level rise indicators. Relative weights were assigned by a pairwise comparison following the Analytic Hierarchy Process approach. The computed vulnerability map highlights that about 30% of the farmlands is under strong and extreme conditions, 28% between marginal and moderate, and 40% under negligible conditions. Results from previous vulnerability assessments are discussed in order to explain their differences in terms of hazard status conceptualization and sensitivity characterization of farmland system.

Resisting the Tourist Gaze. Art Activism Against Cruise Ship Extractivism in the Venice Lagoon

The essay situates Venice’s struggles against the cruise ship industry within a larger framework of resistance against planetary extractive capitalism, emphasising the role of local art-activist initiatives in denouncing the social and the ecological degradation caused by the cruise ship presence in Venice. In the first part, the concept of extractive tourism is introduced and analysed in relation to the case of Venice and the cruise companies’ economic model. The operations and infrastructure of cruise tourism produce extractive relations that entangle and exploit tourists, local communities and the natural environment. The Author examines how mass tourism has aggravated the environmental and social issues of the city of Venice and its lagoon. In the second part, the essay presents a number of artistic projects, specifically by visual artists Eleonora Sovrani, Gli Impresari, Banksy, and Elena Mazzi. These artworks can help us visualise the failures of the current urban development model of the tourist economy, while also exposing the nefarious effects of extractive capitalism on the well-being of the lagoon ecosystem and the human and non-human subjects cohabiting in it.

Sediment Features and Human Activities Structure the Surface Microbial Communities of the Venice Lagoon

Sediment microbial communities play essential roles in marine ecosystem functioning. Their study is crucial to understand how environmental conditions affect microbial diversity and biogeochemical cycles. The Venice Lagoon, one of the largest Adriatic transitional systems, is subjected to different natural and anthropogenic stressors. In this study, surface sediments microbial communities were finely characterized using 16S rRNA gene amplicon sequencing and metagenomics. Samples were collected seasonally in 2019 and 2020 at different sites within Lagoon sub-basins. Our results indicated a stable spatial distribution of the sediment microbiome: salinity, grain size, and total organic carbon were found to be important drivers in shaping prokaryotic communities, while temperature had a minor role. We detected high microbial diversity at all stations, mainly due to low abundant taxa: bacteria represented the vast majority of the reads (∼96.1%), with Woeseia the most abundant genus (∼4.4%). The metagenomic analysis highlighted significant differences among sites in terms of biogeochemical processes (e.g., C, N, Fe, and S metabolism), and cell-cell interaction strategies (e.g., mobilome, regulations and cell signaling). Chioggia, a sandy site subjected to marine influence, presented the highest abundance of ammonia-oxidizing archaeon Candidatus Nitrosopumilus, in accordance with the highest amount of ammonia monooxygenase subunit genes. At the same site, sulfate-reducing bacteria (Desulfobacteria and Desulfobacterales) and sulfur-related genes were found in lower abundance. Marghera and Tresse, the most polluted sites, showed higher abundance of sewage-related bacteria and antibiotic and toxic compound resistance genes. Furthermore, these sites showed higher amount of genes related to cell-cell interaction, such as pathogenicity islands, transposable-elements, and biofilm formation. Our findings highlighted that sediment features and human-related activities have profound and long-term impacts on the surface sediment microbial communities of the Venice Lagoon.

Exploring the partial use of the Mo.S.E. system as effective adaptation to rising flood frequency of Venice

The Venice lagoon (Italy) is particularly vulnerable to the impact of subsidence and sea level rise driven by climate change. Some structural measures have been adopted over time to protect Venice from flooding, among which a system of flap gates (Experimental Electromechanical Module, Mo.S.E., system) has been operational in the testing phase since October 2020. However, relative sea level rise and wind set-up pose relevant management challenges, as a frequent closing of the lagoon would have negative impacts on flushing capacity, the fishing industry, and port activities. Here, the focus is on the hydrodynamic effects of a partial closure of the Mo.S.E. barriers that, compared to closing all the three inlets of the lagoon, could play a role in reducing the economic and environmental impacts of the Mo.S.E. system. The main goal is to identify the flooding events that can be counteracted by closing only the Lido inlet, which is the closest to the city of Venice. Based on the tidal and meteorological dataset collected in the period 2000–2019, a robust modelling exercise identifies a linear relationship between tidal range and reduction of the sea level peaks, which results in the protection of all urban settlements within the lagoon from two-thirds of the flooding events up to a relative sea level rise of +0.4 m.

Macrophytes: A Temporary Sink for Microplastics in Transitional Water Systems

Marine macrophytes are hypothesized to be a major temporary sink for microplastics. In this study, microplastic contamination was investigated in 15 macroalgal species and one seagrass from different sites in two lagoons of the northern Adriatic Sea: the Goro lagoon and the Venice lagoon. A high percentage (94%) of the macrophyte samples contained microplastics, ranging from 0.16 to 330 items g−1 fw, with the prevalent size in the range 30–90 µm and an average contamination per unit of fresh weight of 14 items g−1 fw. Microplastic contamination displayed a site-specific, rather than a species-specific, pattern of accumulation. In addition, exopolysaccharides (EPS) displayed a significant positive correlation with the microplastics ononcontamination on macrophytes acting as glue for the plastic particles available in the water column.