Climate change impacts on marine water quality: The case study of the Northern Adriatic sea

Framework for multirisk climate scenarios across system receptors with application to the Metropolitan City of Venice

Climate change influences the frequency of extreme events that affect both human and natural systems. It requires systemic climate change adaptation to address the complexity of risks across multiple domains and tackle the uncertainties of future scenarios. This paper introduces a multirisk analysis of climate hazard, exposure, vulnerability, and risk severity, specifically designed to hotspot geographic locations and prioritize system receptors that are affected by climate-related extremes. The analysis is demonstrated for the Metropolitan City of Venice. Representative scenarios (RCP4.5 and RCP8.5) of climate threats (i.e., storm surges, pluvial flood, heat waves, and drought) are selected and represented by projections of Regional Climate Models for a 30-year period (2021-2050). A sample of results is as follows. First, an increase in the risk is largely due to drought, pluvial flood, and storm surge, depending on the areas of interest, with the overall situation worsening under the RCP8.5 scenario. Second, particular locations have colocated vulnerable receptors at higher risk, concentrated in the urban centers (e.g., housing, railways, roads) and along the coast (e.g., beaches, wetlands, primary sector). Third, risk communication of potential environmental and socio-economic losses via the multirisk maps is useful to stakeholders and public administration. Fourth, the multirisk maps recommend priorities for future investigation and risk management, such as collection of sensor data, elaboration of mitigations, and adaptation plans at hotspot locations.

Somatic Condition and Reproductive Potential as a Tandem in European Sardine: An Analysis with an Environmental Perspective in the Northern Adriatic (Gulf of Trieste)

The European sardine’s condition is reflected in its reproductive potential, and therefore, in its status as a fishery resource. These values depend on the stock’s distribution and resource availability, which is highly determined by environmental characteristics. Sardines from the productive Gulf of Trieste (in the North Adriatic), located in the northernmost section of the most septentrional Mediterranean sub-basin in which sardine exploitation has traditionally been intensive, were analysed. The reproductive cycle and gonadosomatic index (GSI) were studied. Tissue and mesenteric fat values, as well as vacuity (% V), relative condition (Kn), and hepatosomatic (HSI) indices were evaluated due to their potential relationships with reproductive performance. The results suggested opposite patterns between fat reserves and GSI, while Kn showed a relationship neither with GSI, nor with reproductive stage, which led us to conclude that it is more advisable to apply direct lipid indices to project their contribution to reproductive potential. Moreover, the females’ condition was generally better than that of the males, added to an advanced gonadal development during spring and summer, albeit males and females reached the spawning season together. Moreover, females’ GSIs were significantly higher during active spawning. Furthermore, correlation analyses showed that SST was related with the parameters evaluated, as well as the available portion of productivity for the fish (OPFish), which may explain the sardines’ better condition and GSIs than their chlorophyll concentration.

A Multi-Risk Methodology for the Assessment of Climate Change Impacts in Coastal Zones

Climate change threatens coastal areas, posing significant risks to natural and human systems, including coastal erosion and inundation. This paper presents a multi-risk approach integrating multiple climate-related hazards and exposure and vulnerability factors across different spatial units and temporal scales. The multi-hazard assessment employs an influence matrix to analyze the relationships among hazards (sea-level rise, coastal erosion, and storm surge) and their disjoint probability. The multi-vulnerability considers the susceptibility of the exposed receptors (wetlands, beaches, and urban areas) to different hazards based on multiple indicators (dunes, shoreline evolution, and urbanization rate). The methodology was applied in the North Adriatic coast, producing a ranking of multi-hazard risks by means of GIS maps and statistics. The results highlight that the higher multi-hazard score (meaning presence of all investigated hazards) is near the coastline while multi-vulnerability is relatively high in the whole case study, especially for beaches, wetlands, protected areas, and river mouths. The overall multi-risk score presents a trend similar to multi-hazard and shows that beaches is the receptor most affected by multiple risks (60% of surface in the higher multi-risk classes). Risk statistics were developed for coastal municipalities and local stakeholders to support the setting of adaptation priorities and coastal zone management plans.

Host-microbiota interactions shed light on mortality events in the striped venus clam Chamelea gallina

Mass mortalities due to disease outbreaks have recently affected a number of major taxa in marine ecosystems. Climate- and pollution-induced stress may compromise host immune defenses, increasing the risk of opportunistic diseases. Despite growing evidence that mass mortality events affecting marine species worldwide are strongly influenced by the interplay of numerous environmental factors, the reductionist approaches most frequently used to investigate these factors hindered the interpretation of these multifactorial pathologies. In this study, we propose a broader approach based on the combination of RNA-sequencing and 16S microbiota analyses to decipher the factors underlying mass mortality in the striped venus clam, Chamelea gallina, along the Adriatic coast. On one hand, gene expression profiling and functional analyses of microbial communities showed the over-expression of several genes and molecular pathways involved in xenobiotic metabolism, suggesting potential chemical contamination in mortality sites. On the other hand, the down-regulation of several genes involved in immune and stress response, and the over-representation of opportunistic pathogens such as Vibrio and Photobacterium spp. indicates that these microbial species may take advantage of compromised host immune pathways and defense mechanisms that are potentially affected by chemical exposure, resulting in periodic mortality events. We propose the application of our approach to interpret and anticipate the risks inherent in the combined effects of pollutants and microbes on marine animals in today's rapidly changing environment.