Data on dissolved nitrogen, phosphorus and organic carbon concentrations recorded in the waters of the Venice Lagoon, covering a period spanning from 2007 to 2019, has been subjected to statistical ...analysis meant to evaluate seasonality, spatial variability and trends. The analysis revealed the role of the complex morphology, hydrological features and anthropogenic sources in determining the water quality and the dynamics of the ecosystem. Long-term trends were in line with the picture of the general enhancement of the chemical status of the lagoon observed in the last decades. Further improvements might be achieved dealing with the issues of the untreated effluent discharge in the canals of the urban centre and the agriculture fertilisers coming from the drainage basin and transported by the freshwater tributaries. The collection of such temporal data series has revealed the effectiveness to detect both short and long-term changes in the water quality. The maintenance of such temporal data series will be a useful tool for evaluating future changes arising from the climate change.
The reuse of dredged sediments in ports and lagoons is a big issue as it should not affect the quality and the equilibrium of ecosystems. In the lagoon of Venice, sediment management is of crucial ...importance as sediments are often utilized to built-up structures necessary to limit erosion. However, the impact of sediment reuse on organisms inhabiting this delicate area is poorly known. The Manila clam is a filter-feeding species of high economic and ecological value for the Venice lagoon experiencing a drastic decline in the last decades. In order to define the molecular mechanisms behind sediment toxicity, we exposed clams to sediments sampled from different sites within one of the Venice lagoon navigable canals close to the industrial area. Moreover, we investigated the impacts of dredged sediments on clam's microbial communities. Concentrations of the trace elements and organic chemicals showed increasing concentrations from the city of Venice to sites close to the industrial area of Porto Marghera, where PCDD/Fs and PCBs concentrations were up to 120 times higher than the southern lagoon. While bioaccumulation of organic contaminants of industrial origin reflected sediments' chemical concentrations, metal bioaccumulation was not consistent with metal concentrations measured in sediments probably due to the activation of ABC transporters. At the transcriptional level, we found a persistent activation of the mTORC1 signalling pathway, which is central in the coordination of cellular responses to chemical stress. Microbiota characterization showed the over-representation of potential opportunistic pathogens following exposure to the most contaminated sediments, leading to host immune response activation. Despite the limited acquisition of new microbial species from sediments, the latter play an important role in shaping Manila clam microbial communities. Sediment management in the Venice lagoon will increase in the next years to maintain and create new canals as well as to allow the operation of the new mobile gates at the three Venice lagoon inlets. Our data reveal important transcriptional and microbial changes of Manila clams after exposure to sediments, therefore reuse of dredged sediments represents a potential risk for the conservation of this species and possibly for other organisms inhabiting the Venice lagoon.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Chronic exposure to pollutants affects natural populations, creating specific molecular and biochemical signatures. In the present study, we tested the hypothesis that chronic exposure to pollutants ...might have substantial effects on the Manila clam hologenome long after removal from contaminated sites. To reach this goal, a highly integrative approach was implemented, combining transcriptome, genetic and microbiota analyses with the evaluation of biochemical and histological profiles of the edible Manila clam Ruditapes philippinarum, as it was transplanted for 6 months from the polluted area of Porto Marghera (PM) to the clean area of Chioggia (Venice lagoon, Italy). One month post‐transplantation, PM clams showed several modifications to its resident microbiota, including an overrepresentation of the opportunistic pathogen Arcobacter spp. This may be related to the upregulation of several immune genes in the PM clams, potentially representing a host response to the increased abundance of deleterious bacteria. Six months after transplantation, PM clams demonstrated a lower ability to respond to environmental/physiological stressors related to the summer season, and the hepatopancreas‐associated microbiota still showed different compositions among PM and CH clams. This study confirms that different stressors have predictable effects in clams at different biological levels and demonstrates that chronic exposure to pollutants leads to long‐lasting effects on the animal hologenome. In addition, no genetic differentiation between samples from the two areas was detected, confirming that PM and CH clams belong to a single population. Overall, the obtained responses were largely reversible and potentially related to phenotypic plasticity rather than genetic adaptation. The results here presented will be functional for the assessment of the environmental risk imposed by chemicals on an economically important bivalve species.
A comprehensive dataset on dissolved trace element concentrations spanning a decade (2008-2017), collected during monitoring campaigns, is the result of an investigation meant to evaluate spatial ...variability and temporal evolution in the Venice Lagoon waters. The concentration levels at the different sites unfold that the lagoon is not homogeneous but a system of various parts having different characteristics affected by various pollutant sources, meanwhile the analysis for trend performed both at each site and at the entire lagoon as a whole revealed that arsenic and heavy metals showed little variations or decreasing trends, with the exception of iron that may have had an overall increase in concentrations.
Atmospheric deposition data on trace elements from ten bulk sampler stations in the Venice Lagoon, covering a period spanning from 2007 to 2017, are presented and discussed. Results have been ...statistically analysed and used to estimate fall-out loads on the Lagoon. The Venice Lagoon is not only exposed to long-range transport of contaminants but it is also affected by local urban and industrial emissions. A sharp drop off of the Cd load since 2011 has been observed tied up with decreasing flux recorded at the station in the nearby glass-making district, where decreasing trends have also been detected for other elements. Decreasing long-term trends have been observed for Ni and Sb loads while Zn load has shown a small increase.
Contaminated soil with high mobility of potentially toxic elements (PTEs) can threaten the environment and human health. Precisely quantifying trends in PTEs accumulation in the soil under changing ...pH conditions is essential to minimize potential exposure. However, this has long been a hard-to-monitor subject experimentally due to the relatively low content of PTEs and the lack of detailed knowledge of the minerals that control PTEs' leaching. Here we profoundly investigate the critical role of soil mineralogy in PTEs release and predict the leaching behavior of PTEs by exploiting the modeling approach. The investigated sample comes from a brownfield site devoted to fertilizers production. Hematite, jarosite, and gypsum are the major mineralogical phases, with zinc sulfate, anglesite, kintoreite, and Pb-bearing jarosite being identified as the dominant Pb and Zn phases. pH-dependent leaching tests in combination with geochemical modeling were used to reveal the potential leaching mechanisms and contaminants solubility-controlling phases at pH ranging from 1 to 12. The experimental and modeling results both demonstrated that Pb and Zn have an amphoteric leaching behavior, with the lowest leached concentrations at the neutral/alkaline region around pH values from 8.0 to 10.0. The calculated saturation indexes suggest that Pb retention is controlled by anglesite, cerussite, and hydrocerussite, while Zn retention is attributed to zinc carbonates and hydroxides. Further, jarosite and ferrihydrite may play a role in Pb and Zn retention. In comparison, the sulfate release increases with pH values, which is governed by the equilibrium of jarosite, gypsum, and anglesite. The overall results highlight the value of converging experimental-geochemical modeling approaches to gain a deeper understanding of PTEs' release and retention, which is difficult to reveal through experiments alone. These advances may be pivotal in the sustainable management and design of remediation strategies.
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•Assessing PTEs’ leaching behavior through bulk mineralogical characterization.•Geochemical modeling predicts the leaching behavior under a broad pH range.•pH and mineralogy synergistically impact the leaching of Pb and Zn•Remediation strategies can be elaborated by combining geochemical models and experiments.
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.
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•In recent years recurrent bivalve mass mortalities considerably increased around the world.•Criticalities affecting clam stocks in different sites within the Venice lagoon have been characterized.•Microbiota and gene expression profiling allowed the identification of seasonal- and site-specific environmental stressors.•Identification of molecular mechanisms adopted by Manila clam to cope with stressors
The assessment of marine environmental health is a complex but fundamental task both for ecosystem conservation and food safety related to the human consumption of marine products. Manila clams ...inhabiting the Venice Lagoon constitute an excellent case study for evaluating the effects of complex mixtures of industrial and urban effluents on aquatic organisms. Clams were collected in different seasons at four locations within the Venice Lagoon. The sampling sites were characterized by a range of pollutant concentrations and included Porto Marghera, a highly polluted industrial area where clam harvesting for human consumption is strictly forbidden. Pooled soft tissues were subjected to mass spectroscopy analysis to measure the concentrations of PCDDs/PCDFs/PCBs‐DL, PCBs, PBDEs, HCB and PAHs, and pooled digestive gland samples were used for gene expression profiling. While seasonal variation was found to be responsible for the largest proportion of transcriptional changes, significance analysis of microarrays quantitative correlation analysis identified 162 transcripts that were correlated with at least one class of chemicals measured in the samples from the four different sampling sites. Prediction Analysis of Microarrays (PAM) identified a minimal set of seven genes that correctly assigned samples collected in the restricted polluted area (Porto Marghera), independent of the season in which they were collected. An integrated approach combining transcriptomics and chemical analyses of the Manila clam provided a global picture of how Manila clams respond to complex mixtures of xenobiotics and their interplay with other biotic and abiotic factors. We were also able to identify gene expression signatures for different classes of chemicals and a set of robust biomarkers of exposure to these chemicals.
Porto Marghera is an industrial district located in the Venice Lagoon (Italy). The century-long industrial activity has left a heavy environmental burden. Data records (2004-2016) of trace metals, ...arsenic and suspended solids in the waters of the industrial canals of Porto Marghera were analyzed for trends. Decreasing trends were detected for Cu, Zn, Cr and Pb, as well as suspended solids. No significant trends for As and Cd were evident. A positive trend of Fe was detected in one sampling site.
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