Venice Lagoon Research Articles

Return periods of extreme sea levels: From magnitude to frequency, duration and seasonality. Implications in a regulated coastal lagoon

Extreme sea levels (ESLs) affect coastal ecosystems worldwide. Protection and adaptation strategies rely on the characterization of the extreme's occurrence probability in the future. However, knowledge on the occurrence rate and duration of ESLs is also needed to properly characterize the associated future risk. In this paper, we focus on the Venice lagoon, where a system of storm surge barriers can disconnect the lagoon from the sea to mitigate ESLs. Using long-term (96 years) sea level records, we model occurrence rate and duration of ESLs while accounting explicitly for seasonality and mean sea level rise. While historically ESLs occurred in the winter season, we project a significant increase (up to 10-fold with a mean sea level increase of +100 cm) of the occurrence rate also in the summer season, when disconnections from the sea can have profound impacts on the lagoon's ecosystem. We also predict an increase in ESLs durations up to 200 h, leading to longer disconnections of the lagoon from the sea in the future. Therefore, several adaptation strategies will be needed to limit the adverse effects of storm surge barriers on the lagoon ecosystem.

Emissions of pharmaceuticals and plant protection products to the lagoon of Venice: development of a new emission inventory

Estimating the emissions of chemical pollutants to water is a fundamental step for the development and application of effective and sustainable management strategies of water resources, but methods applied so far to build chemicals inventories at the European or national scale show several limitations when applied at the local scale. The issue is particularly relevant when considering contaminants of emerging concern (CECs), whose environmental releases and occurrence are still poorly studied and understood.In this work, an approach to estimate water emissions of nine active pharmaceutical ingredients (APIs) and ten most applied plant protection products (PPPs) is presented, considering proxy indicators (e.g., sales data and census information). The application area is the lagoon of Venice (Italy), a complex transitional environment highly influenced by anthropic pressures (e.g., agricultural and industrial activities, animal breeding, and wastewater discharge). The presented approach can be tailored to the information available for any local scale case study.Data on annual regional sales of PPPs and APIs were integrated with georeferenced demographic and economic statistics (such as census and land-use information) to estimate chemicals emissions to surface water and groundwater. A sensitivity and uncertainty analysis identified the main factors affecting emissions estimates, and those contributing more significantly to results uncertainty.Results showed the highest estimated emissions of APIs for antibiotics (i.e., amoxicillin, clarithromycin, azithromycin, and ciprofloxacin) used for humans and animals, while most of hormones’ emission (i.e., 17- α-ethinylestradiol and 17-β-estradiol) derived from animal breeding. Regarding PPPs, glyphosate and imidacloprid emissions were one to two orders of magnitude higher compared to the other chemicals.Uncertainty and sensitivity analysis showed that the variability of each parameter used to estimate emissions depends greatly both on the target chemical and the specific emission source considered. Excretion rates and removal during wastewater treatment were major key parameters for all the target pharmaceutical compounds, while for PPPs the key parameter was their loss into the natural waters after application.

Roman ‘Well-cisterns’, Navigational Routes, and Landscape Modifications in the Venice Lagoon and Northeastern Adriatic

Underwater investigations in the lagoon of Venice have revealed a partially preserved structure interpreted as a Roman ‘well-cistern’. It is indeed very similar to another, better-preserved building excavated in the same area. The analysis of the mortar, the evaluation of the depth of the structure base in relation to relative sea level, and the absence of foundation poles in the underlying soft lagoon mud support such interpretation. A comparison with other poorly-studied Roman buildings of the same type located along the North Adriatic littoral suggests that they were probably used to supply ships with fresh water. In the Middle Ages, similar structures were used in the islands of the lagoon for sustenance of its residents and became a characteristic of the small squares (campi) of Venice.

A high‐impact meso‐beta vortex in the Adriatic Sea

AbstractOn the evening of November 12, 2019, an exceptional high tide – the second‐highest in the ranking since sea‐level data have been recorded – hit the city of Venice in northern Italy and its entire lagoon, damaging a large part of its historical center. A small warm‐core mesoscale cyclone, which formed in the central Adriatic Sea and intensified during its northwestward movement toward the Venice lagoon, was responsible for the event. The cyclone was preceded by intense northeasterlies (Bora) in the northern Adriatic, which turned to southeasterlies (Sirocco) and then southwesterlies after its passage. Simulations with different initialization times were carried out with the Weather Research and Forecasting (WRF) model. Simulation results show a strong sensitivity to the initial conditions, since the track (and strength) of the cyclone was determined by the exact position of an upper‐level potential vorticity (PV) streamer. The factors responsible for the cyclone development and its characteristics are also investigated. The pre‐existence of positive low‐level cyclonic vorticity, associated with the convergence of the Sirocco and Bora winds in the central Adriatic, made the environment favorable for cyclone development. Also, the interaction between the upper‐level PV anomaly and the low‐level baroclinicity, created by the advection of warm, humid air associated with the Sirocco, was responsible for the cyclone's intensification, in a manner similar to a transitory (stable) baroclinic interaction at small horizontal scales. Sensitivity experiments reveal that convection, latent heat release and sea‐surface fluxes did not play a significant role, indicating that this cyclone did not show tropical‐like characteristics, notwithstanding its low‐level warm core. Thus, the warm‐core feature appears mainly as a characteristic of the environment in which the cyclone developed rather than a consequence of diabatic processes. Lastly, the cyclone does not fall into any of the existing categories for Adriatic cyclones.

Technical-economic assessments on the feasibility of new infrastructures serving seaport and dry port of Venice

Despite the millenary tradition of the city, the current port of Venice was built only about a hundred of years ago and located in a suburb named Marghera. The lack of an updated regulatory plan and of suitable inland transport connections have made it difficult to increase commercial traffic after the crisis of the chemical industry, although a strong growth in the luxury cruise industry. Only the construction of new infrastructures (both land and sea side) and the recovery of many abandoned areas have given a new impetus to the port.However, the reduction in maritime traffic caused by the COVID-19 pandemic has led to a drastic decline in commercial movements and cruises, with the risk of a total economic collapse. The recent approval of the National Recovery and Resilience Plan, that identifies ports as strategic infrastructures, and the approval of the “Strategic Development Plan” aimed at establishing the “Simplified Logistics Zone of the Port of Venice and Rodigino” by the Veneto Region, have directed new investments towards the port of Venice. Furthermore, the growing awareness of the weakness of the lagoon ecosystem, the need to preserve Venice and the impossibility of enlarging the port areas have led to the need for new infrastructures that still allow the use of the current port.This article will mainly evaluate the technical-economic feasibility of new docking points outside the Venice lagoon that can be used by passenger ships of gross tonnage over 40,000 tons and by transoceanic container ships. Measures to improve the accessibility of the current seaport and dry port through new road and rail infrastructures will also be examined and evaluated. Indications are given regarding the necessary regeneration of the current sea- and dry-port and interventions aimed at ensuring greater environmental sustainability, such as cold ironing and electric mobility.

Estimation of hydraulic parameters in a heterogeneous low‐lying farmland near Venice

AbstractEstimating the hydraulic properties of the vadose zone is essential to understand soil‐water dynamics and achieving appropriate water management in agricultural lands. Inverse modelling methods are commonly used to estimate hydraulic properties from field observations. Unlike the extensively applied local search methodologies, data assimilation techniques can fully account for multiple uncertainties and are becoming a widely used tool for estimating hydraulic parameters. However, only few applications on real field tests are available. The main objective of this study was to estimate the van Genuchten‐Mualem (VGM) parameters and the saturated hydraulic conductivity () of a heterogeneous low‐lying farmland at the margin of the Venice Lagoon, Italy, characterized by high peat content, sandy drifts, and a very shallow water table. To this end, two methods were tested, that is, the Ensemble Smoother (ES) and the Levenberg–Marquardt (LM) algorithm associated with hydrological modelling performed with Hydrus‐1D. Volumetric water content (VWC) observations were collected at three monitoring sites from May to September 2011. Results on parameters highlighted that the ES technique effectively reduced the uncertainty of and , but it was less effective on and . The results on VWC showed that the ES efficiency decreased with the increasing non‐linearity of the system (e.g., higher sand content) and when the variability of the experimental data was lower (e.g., deepest soil layers where saturation remained permanently close to 1). Both LM and ES allowed to reproduce the VWC observations in the calibration and validation phases, with the former and the latter performing better in the case of sandy and peat soils, respectively. As concerns the method applicability, the ES was less time‐demanding as it efficiently updated all the parameters at once and was less dependent on the user choices. Finally, the paper points out the importance of previous knowledge of the VGM parameters (e.g., from lab hydraulic analyses) in defining the constraints for the optimization.

Mosaic of Submerged Habitats in the Venice Lagoon Shows Signs of Marinization

Mosaic of Submerged Habitats in the Venice Lagoon Shows Signs of Marinization

The Gondola: a boat to respond to the history, and the morpho-dynamics of the Venice Lagoon

Origin and evolution of the gondola have been reconstructed from historical and documentary written and pictorial sources (figures in books, engravings and paintings), in relation to the physical environment of the Lagoon, its morpho-dynamics with shallow and deep waters, marshes and canals. Particular care has been applied to the physical and hydrodynamic aspects in order to interpret the data and understand how the ancient Venetians could have had an advanced knowledge of the tidal range from sea stairs, tidal phase from the algae colour and direction, bottom depth from surface ripples, and exchanges between the Lagoon and the sea from suspended debris. The various elements of the boat are considered in terms of use and physical advantage, e.g. rowing style, cabin, hull and decorations. The boat evolution has been followed and documented over the centuries. This study clarifies the original shape of the gondola in the 11th century, from the analysis of the contemporary manuscripts and Byzantine mosaics in Ravenna and Venice, and a tablet of the early 14th century. In the 16th century, the gondola changed shape and size. The reason of this restyling was unknown, but has been found in the contemporary edicts, diaries and chronicles and other historical sources. The transformation was kept as a military secret, as well the production of a fleet of small boats provided of rostrums to sail on the rivers Po and Adige and fight against Ferrara and its Allies of the League of Cambrai. A comparison with the Viking- Norman vessels of Bayeux, Palermo and some codices show several strong analogies with the military gondolas of the 16th century. An overview of the written and pictorial sources has allowed to classify the various gondola types and recognize several technical details. Finally, the size and depth have been considered to interpret the ancient chronicles that mentioned that in the occasion of the most extreme storm surges, the gondolas could ride on San Marco Square, i.e. the flooding water depth necessary to float and to navigate over street paving.

Evaluation of the Bio-Stimulating Activity of Lake Algae Extracts on Edible Cacti Mammillaria prolifera and Mammillaria glassii.

The research aimed to test different seaweed extracts derived from three macroalgae representatives, namely, Rhodophyta, Chlorophyta and Phaeophyceae, as a bio-fertiliser for the growth of Mammillaria prolifera and Mammillaria glassii and the production of edible fruits. The experiments started in September 2021 and were conducted in the greenhouses of CREA-OF in Pescia (PT). Three different algae, namely, Hypnea cornuta (Rhodophyta), Ulva ohnoi (Chlorophyta), collected from the brackish lake Ganzirri, in Messina, and Sargassum muticum (Phaeophyceae) from Venice lagoon, were tested. The experimental trial showed a significant improvement in the agronomic parameters analysed for the growth and production of cactus plants and fruits treated with the selected algae. A significant increase was found in the sugar, vitamin A, vitamin C and vitamin E content of the fruits of treated plants. In particular, the thesis with Ulva ohnoi was the best for plant growth and fruit production with a higher sugar and vitamin content. This experiment confirms the algae's ability to stimulate soil microflora and microfauna, promoting nutrient uptake, participating in organic matter mineralisation processes and significantly influencing the nutraceutical compounds in the fruits.

Multidisciplinary long-term survey of Manila clam grown in farming sites subjected to different environmental conditions

In recent years recurrent bivalve mass mortalities considerably increased around the world, causing the collapse of natural and farmed populations. Venice Lagoon has historically represented one of the major production areas of the Manila clam Ruditapes philippinarum in Europe. However, in the last 20 years a 75 % decrease in the annual production has been experienced. While climate change and anthropogenic interventions may have played a key role in natural and farmed stocks reductions, no studies investigated at multiple levels the environmental stressors affecting farmed Manila clam to date.In this work we carried out a long-term monitoring campaign on Manila clam reared in four farming sites located at different distances from the southern Venice Lagoon inlet, integrating (meta)genomic approaches (i.e. RNA-seq; microbiota characterization), biometric measurements and chemical-physical parameters. Our study allowed to characterize the molecular mechanisms adopted by this species to cope with the different environmental conditions characterizing farming sites and to propose hypotheses to explain mortality events observed in recent years. Among the most important findings, the disruption of clam's immune response, the spread of Vibrio spp., and the up-regulation of molecular pathways involved in xenobiotic metabolism suggested major environmental stressors affecting clams farmed in sites placed close to Chioggia's inlet, where highest mortality was also observed.Overall, our study provides knowledge-based tools for managing Manila clam farming on-growing areas. In addition, the collected data is a snapshot of the time immediately before the commissioning of MoSE, a system of mobile barriers aimed at protecting Venice from high tides, and will represent a baseline for future studies on the effects of MoSE on clams farming and more in general on the ecology of the Venice Lagoon.

Seabirds as Biomonitors of Mercury Bioavailability in the Venice Lagoon

Seabirds accumulate mercury (Hg) due to their long-life span together with their high trophic position. A Hg monitoring in Venice's Lagoon using three seabird species occupying different trophic habitat (Thalasseus sandvicensis, Ichthyaetus melanocephalus, and Chroicocephalus ridibundus) confirmed that fledgelings might effectively be used as sentinels of Hg bioavailability. The significant differences in Hg residues in feathers observed among the species highlighted a possible differential exposure due to different diets, with C. ridibundus accumulating more Hg than the other species. Average residues in feathers were not above the threshold associated with adverse effects on birds (5mg kg- 1). Nevertheless, a large part of the C. ridibundus individuals (58%) exceeded the adverse effect level, underlining the need for strengthening Hg monitoring. Seabirds indeed may provide relevant insight on Hg transfer in food webs and a better picture of the hazards to men when bird species forage on species exploited for human consumption.

Sedimentation Rates: Anthropogenic Impacts and Environmental Changes in Transitional Water Systems

The trophic evolution of the Venice lagoon was analyzed by studying the particulate collected monthly with sedimentation traps in many areas of the Venice lagoon since 1989, and at Goro in 2018–2019. Sedimentation rates were strongly related to the presence of macrophytes, which reduced sediment resuspension, and to anthropogenic pressures, such as clam harvesting and naval-boat traffic, that triggered sediment resuspension and loss. The highest mean annual sedimentation rates (from 2000 to over 4000 g DWT m−2 day−1) have been recorded in many areas of the Venice lagoon between 1998–1999 to 2001–2002, during the intense fishing activities of the clam Ruditapes philippinarum. High values (daily peaks up to 5224 g DWT m−2 day−1) were also recorded in areas affected by marine and/or recreational traffic, due to the high wave motion. In contrast, the presence of high biomasses of macroalgae, or seagrasses, reduced significantly sediment resuspension and settlement, with mean annual sedimentation rates ranging between 40 and 140 g DWT m−2 day−1 and minimum values of 6–10 g DWT m−2 day−1. High sedimentation rates were strongly related to a lower sediment grain-size, with loss of the fine fraction and dispersion of nutrients and pollutants in the whole lagoon.

Environmental DNA metabarcoding reveals spatial and seasonal patterns in the fish community in the Venice Lagoon

Environmental DNA (eDNA) is an emerging tool for assessing biodiversity and understanding spatial and temporal community patterns and processes, directly from DNA sequencing of environmental samples such as air, water, and sediments. We applied eDNA methods to monitor bony fish communities, detecting as well locally allochthonous species, and to reveal seasonal patterns at two sites in the Venice Lagoon. We analyzed 17 water samples collected over 12 months at two ecologically distinct sites by using available primers for teleosts and High Throughput Illumina sequencing. We identified 1,289 amplicon sequence variants (ASVs) assigned to 62 fish taxa. Most of the species known to inhabit or to enter the Venice Lagoon were detected, with eDNA data reflecting differences in fish communities between the internal (freshwater associated) and the external (sea associated) part of the lagoon. Moreover, seasonal trends of migration have been portrayed, highlighting the most involved species and disclosing possible clashes between migration events and the temporary interruption of sea-lagoon connectivity due to MOSE (MOdulo Sperimentale Elettromeccanico). Of interest, the first-time detection of Oceanic puffer (Lagocephalus lagocephalus) DNA in the Venice Lagoon provides evidence of the further northward expansion of this species in the high Adriatic Sea. eDNA successfully profiled fish communities by season and habitat in the Venice Lagoon. Our results support routine application of eDNA to monitor potential ecological consequences of MOSE closures in this World Heritage site.

The impact of climate change on the storm surges of the Mediterranean Sea: Coastal sea level responses to deep depression atmospheric systems

The impact of climate change on the storm surges of the Mediterranean Sea: Coastal sea level responses to deep depression atmospheric systems

In-situ loading experiments reveal how the subsurface affects coastal marsh survival

Over the past decades coastal marshes around the world have declined dramatically. Their deterioration is controlled by scarcity of sediments, erosion and accelerated rise of relative sea-level. The feedbacks between these processes control marsh evolution and determine their long-term survivability. Aggradation of a marsh to keep pace with relative sea-level rise mainly depends on the interplay between sedimentation and autocompaction, but their interactions are severely understudied. Here we present an in-situ loading experiment applied in the Venice Lagoon, Italy, to assess long-term autocompaction, with subsurface displacements and pressure monitored during loading cycles, up to ∼40 kN applied on a ∼4 m2 surface. Two identical experiments carried out in inorganic and organic soil-dominated marshes provided unique insights on the spatio-temporal subsurface dynamics. The large differences in behavior and maximum compaction (6 vs 32 mm) underscore the crucial role of autocompaction and soil heterogeneity when predicting the fate of coastal marshes worldwide.

Interspecific Aggression and Food Competition between the Global Invader Palaemon macrodactylus and the Native Palaemon elegans

The impact of invasive alien species on native communities can act at different levels both by affecting the ecosystem’s structure (i.e., mainly in the case of vegetation) and through direct interactions (i.e., competition for food or space). Behavioral studies under controlled conditions can provide relevant information on both the invasive potential of alien species and the potential impact of the invaders on the local native species. In the laboratory, the competition for food resources between the invasive oriental shrimp Palaemon macrodactylus, Rathbun, 1902, and the Mediterranean native shrimp Palaemon elegans, Rathke, 1836, was analyzed. These species are typical residents of coastal transitional and estuarine waters, so the experiments were carried out using two salinity conditions that characterize the coastal lagoon of Venice. Although at both salinity treatments the alien species tended to be more aggressive than the native one, significant differences between the two species were mainly observed at a salinity of 30. In particular, at a salinity of 30, P. macrodactylus spent more time attending to the food source than the native species. The results are discussed in light of the potential inter-specific competition between the two species within the conditions of the Venice lagoon.

Mid-XIX Century Estuary SST Time Series Recorded in the Venice Lagoon

Sea surface temperature (SST) is of paramount importance for comprehending ocean dynamics and hence the Earth’s climate system. Accordingly, it is also the most measured oceanographic parameter. However, until the end of the XIX century, no continuous time series of SST seems to exist, with most of the available data deriving from measurements on ships. Here, we present a continuous digitalized record of surface water measurements originally written in a book published in 1853. The measurements were retrieved thrice daily in the Venice lagoon, in the northeastern part of the Italian peninsula, from June to August 1851 and 1852. To the best of our knowledge, these data constitute the oldest time series of the entire world ocean. The measurements were performed by immersing a Réaumur thermometer a few meters deep in the lagoon water at 8 a.m., 12 p.m., and 8 p.m. Despite several limitations affecting these data (e.g., lacking information regarding the exact water depth where measurements were performed and instrumental metadata), they are of utmost significance, as they put many decades backward the date of the development of a fundamental aspect of oceanographic observations. Moreover, the data were collected close to the Punta della Salute site, where actual sea water temperature measurements have been performed since 2002. Therefore, a unique comparison between surface water temperatures within the Lagoon of Venice across three centuries is possible.

Pre-industrial sediment concentrations of metals: insights from the Venice lagoon (Italy).

This study investigated the occurrence of selected metals and metalloids (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) in radio-dated sediment cores from a coastal lagoon (Lagoon of Venice, Italy) by critically reviewing and grouping available data. Pre-industrial concentrations (pICs, estimated for the period before the early 1900s) for the Venice lagoon are identified according to the 2σ statistical procedure (2σ-pICs), i.e., the upper bound values of the dataset distribution. Results show the following 2σ-pICs (µg/g, d.w.): As 15,9; Cd 0,6; Cr 38,0; Cu 18,1; Hg 1,1; Ni 32,9; Pb 29,4; Zn 94,5. Most of the estimated 2σ-pICs are comparable to previously assessed background values. In the case of Hg, on the contrary, 2σ-pIC is remarkably higher than background values, reflecting a significant anthropogenic contribution also in the pre-industrial period. The results of this work may support the evaluation of the temporal evolution of metal concentrations in sediments of the Venice lagoon. Results are compared with background concentrations (BC) observed in previous studies conducted in the lagoon and in other areas of the Adriatic Sea, as well as with benchmarks set in Italy for sediment assessment.

Interannual-to-multidecadal sea-level changes in the Venice lagoon and their impact on flood frequency

Interannual-to-multidecadal sea-level changes in the Venice lagoon and their impact on flood frequency

Two-dimensional model of flow and transport in porous media: Linking heterogeneous anisotropy with stratal patterns in meandering tidal channel deposits of the Venice Lagoon (Italy)

Understanding the internal structure of permeable and impermeable sediments (e.g. point-bars and tidal-flat deposits) generated by the evolution of meandering tidal channels is essential for accurate modeling of groundwater flow and contaminant transport in coastal areas. The detailed reconstruction of stratal geometry and hydraulic properties from measurements must be accompanied by depositional history information. In this work, we use high resolution reconstructions of ancient tidal channels of the Venice Lagoon (Italy) to drive 2D simulations of groundwater flow and transport, showing the importance of incorporating information on the sediment accumulation processes into the hydraulic characteristics and how horizontal anisotropy emerging from these processes significantly influences transport. Effective hydraulic conductivity is modeled with a heterogeneous 2D anisotropic tensor with principal directions aligned with observed sedimentation sequences. Comparison of flow and solute dynamics simulated using reconstructed and theoretical hydraulic properties show drastically different pathways of solute propagation.