Northwestern Adriatic Sea Research Articles

P21-38 Heavy metals in the blue crabs (Callinectes sapidus) collected in coastal lagoons and shallow marine waters of Northwestern Adriatic Sea

P21-38 Heavy metals in the blue crabs (Callinectes sapidus) collected in coastal lagoons and shallow marine waters of Northwestern Adriatic Sea

Molecular monitoring of Dinophysis species assemblage in mussel farms in the Northwestern Adriatic Sea

Several Dinophysis species can produce potent lipophilic toxins that pose a risk to human health when contaminated seafood is consumed, especially filter-feeding bivalve mussels. In the mussel farms of the Northwestern Adriatic Sea, seawater and seafood are regularly monitored for the presence of Dinophysis species and their associated toxins, but the current methodological approaches, such as light microscopy determinations, require a long time to make results available to local authorities. A molecular qPCR-based assay can be used to quantify various toxic Dinophysis species in a shorter timeframe. However, this approach is not currently employed in official testing activities. In this study, field samples were collected monthly or bi-weekly over one year from various mussel farms along the Northwestern Adriatic coast. The abundance of Dinophysis species in the seawater was determined using both traditional microscopy and qPCR assays. In addition, the concentration of lipophilic toxins for DSP in mussel flesh was quantified using LC-MS/MS focusing on the okadaic acid group. Dinophysis spp. site-specific single cells were isolated and analysed by qPCR yielding a mean rDNA copy number per cell of 1.21 × 104 ± 1.81 × 103. The qPCR assay gave an efficiency of 98 % and detected up to 10 copies of the rDNA target gene. The qPCR and light microscopy determinations in environmental samples showed a significant positive correlation (Spearman rs = 0.57, p-value < 0.001) with a ratio of 2.24 between the two quantification methods, indicating that light microscopy estimates were generally 44.6 % lower than those obtained by the qPCR assay. The qPCR approach showed several advantages such as rapidity, sensitivity and efficiency over conventional microscopy analysis, showing its potential future role in phytoplankton monitoring under the Official Controls Regulations for shellfish.

Variability of hydrographic and biogeochemical properties in the North-western Adriatic coastal waters in relation to river discharge and climate changes

The dynamics of hydrographic and biogeochemical properties in a Northwestern coastal area of the Adriatic Sea were investigated. The time series data from continuous observation (2007–2022) allowed the investigation of annual trends and seasonal cycles along a coastal transect influenced by local river discharge. Various statistical models were used to investigate water temperature, salinity, chlorophyll a, dissolved organic, inorganic and particulate nutrients, precipitation and river discharge. It was found that the local river discharge regime played an essential role in interannual, and seasonal biogeochemical dynamics associated with global climate change in the Mediterranean region. A significant trend towards oligotrophic conditions was detected, as evidenced by the downward trend in the river mouth and on the sea of chlorophyll a (−0.2 μg L−1 in the sea), dissolved organic and inorganic nitrogen and phosphorus (i.e., −0.43 μM yr−1 of DON in the sea and −6.67 of DIN μM yr−1 in the river mouth or −0.07 μM yr−1 of DOP and −0.02 μM yr−1 of DIP in the river mouth) and silicate (−2.47 μM yr−1 in the river mouth) concentrations. Salinity showed a long-term increase in the sea (0.08 yr−1), corresponding to a significant decrease in water discharge from the local river (−0.27 m3 s−1 yr−1) and precipitation (−0.06 mm yr−1). The dissolved organic and inorganic nutrients highlighted a different seasonal accumulation under the river runoff regime. The nutrient enrichment was predominantly driven by river contribution. Data analysis showed that the coastal biogeochemical properties dynamics were mostly influenced by river discharge and precipitation regimes, which in turn are driven by climate change variability in the North-western Adriatic Sea.

First Report of Pinnatoxin-G (PnTX-G) in a Marine-Coastal Area of the Adriatic Sea Associated with the Presence of the Dinoflagellate Vulcanodinium rugosum.

This study reports the first detection of the marine neurotoxin pinnatoxin-G (PnTX-G) in clams collected in the northwestern Adriatic Sea (Italy). It also represents the first report of the potential toxin-producing dinoflagellate, Vulcanodinium rugosum, in Italian seas. This result, from the coasts of the Emilia-Romagna Region, indicates a successful colonization process, reflecting conditions in France where V. rugosum was initially documented. In this case, the concentration of PnTXs was very low, making further sampling necessary to fully understand the extent of the phenomenon. Discussions on the need to obtain more data to support a proper risk assessment and the need to implement a monitoring program that includes emerging marine biotoxins are also included.

Signature of the anthropogenic impacts on the epipelagic microbiome of the North-Western Adriatic Sea (Mediterranean Sea)

IntroductionIn our paper, we explored the impact of different anthropogenic stressors, namely, mussel farming, methane extraction platforms, and summer mass tourism, on the epipelagic microbiomes of the North-Western Adriatic Sea.MethodsBy 16S rRNA gene sequencing, we provided the epipelagic microbiome layout from selected sites corresponding to each of the considered impacts. As an unimpacted reference, we used already published 16S rRNA sequencing data.ResultsAccording to our findings, each one of the anthropogenic stressors resulted in a peculiar increase of specific epipelagic microbial components, including copiotrophic R-strategists and host-restricted bacteria, as well as some pathobiome components, the latter being detected exclusively in impacted sites. Particularly, potentially harmful pathogenic species such as Legionella impletisoli and Staphylococcus epidermidis have been detected in proximity to the mussel farms, and Escherichia coli and Campylobacter ureolyticus were present close to the methane extraction platform and at the summer mass tourism site, respectively. Particularly, C. ureolyticus is an emerging human gastrointestinal pathogen, capable of destroying intestinal microvilli.DiscussionIn addition to providing evidence supporting the existence of recognizable and impact-driven fingerprints on the epipelagic marine microbiome peculiar to the different anthropogenic stressors, our findings also raise concern about the ecological relevance of the observed changes, in terms of possible loss of ecosystem services and also for the potential release of pathogenic microorganisms in the environment.

Offshore distribution of yelkouan shearwaters in the north-western Adriatic Sea

: The yelkouan shearwater Puffinus yelkouan is endemic to the Mediterranean and Black Seas, and classified as Vulnerable in the IUCN Red List. Information on the species’ distribution and habitat use in the eastern Mediterranean is scant, and only a few studies were based on direct visual observations in offshore waters. Here, we provide information on 1) the occurrence of yelkouan shearwaters within a 3000 km2 study area off the region of Veneto, Italy, in the northwestern Adriatic Sea, based on visual surveys conducted from small boats between April and October 2018–2022 (effort: 169 days, 23,836 km), and 2) the geographic, bathymetric and oceanographic variables likely to drive the species’ offshore distribution. Yelkouan shearwaters (238 sightings, 916 individuals) were observed in waters 9–33 m deep, between 2 and 24 km from the coast. Individual counts ranged between 1 and 100, with 95% of the encounters having less than 10 individuals. An Explainable Boosting Machine model – a machine learning technique based on generalized additive models – selected chlorophyll a as the most important variable to explain the species’ occurrence, followed by distance from the coast, and bottom depth. The model indicated a higher occurrence in waters with chlorophyll a less than ~2.3 mg/m3 , farther than ~15 km from the coast, and deeper than ~22 m. The effects of SST, salinity, and day of the year were less clear. This study provides insight into the offshore distribution of yelkouan shearwaters, within one of the Mediterranean areas most exposed to cumulative human threats

Microbiome variation at the clam-sediment interface may explain changes in local productivity of Chamelea gallina in the North Adriatic sea

BackgroundThe clam Chamelea gallina is an ecologically and economically important marine species in the Northwestern Adriatic Sea, which currently suffers from occasional, and still unexplained, widespread mortality events. In order to provide some glimpses in this direction, this study explores the connections between microbiome variations at the clam-sediment interface and the nutritional status of clams collected at four Italian production sites along the Emilia Romagna coast, with different mortality incidence, higher in the Northern sites and lower in the Southern sites.ResultsAccording to our findings, each production site showed a peculiar microbiome arrangement at the clam-sediment interface, with features that clearly differentiate the Northern and Southern sites, with the latter also being associated with a better nutritional status of the animal. Interestingly, the C. gallina digestive gland microbiome from the Southern sites was enriched in some health-promoting microbiome components, capable of supplying the host with essential nutrients and defensive molecules. Furthermore, in experiments conducted under controlled conditions in aquaria, we provided preliminary evidence of the prebiotic action of sediments from the Southern sites, allowing to boost the acquisition of previously identified health-promoting components of the digestive gland microbiome by clams from the Northern sites.ConclusionsTaken together, our findings may help define innovative microbiome-based management strategies for the preservation of the productivity of C. gallina clams in the Adriatic Sea, through the identification and maintenance of a probiotic niche at the animal-sediment interface.

Trophic Partitioning among Three Mesopredatory Shark Species Inhabiting the Northwestern Adriatic Sea

While the general diet of Mediterranean elasmobranchs has been widely studied, little is known about food partitioning and competition among sympatric species, despite these being important forces structuring marine communities. Using stomach content and stable isotope analyses, we investigated diet and trophic levels and evaluated the diet overlap and partitioning of Scyliorhinus canicula, Mustelus mustelus, and M. punctulatus in the northwestern Adriatic Sea. These shark species were confirmed as opportunistic mesopredators, but significant differences in their diets emerged. The two bentho-demersal Mustelus species had a larger trophic overlap with S. canicula than between each other. Given the pronounced morphological similarity of these two Mustelus species, this is likely a strategy to limit competition. The strictly benthic S. canicula showed a more varied diet compared to the other species. Stable isotope analysis highlighted that despite the smaller size and overlapping diets, S. canicula occupied a slightly higher trophic level. A better characterization of the trophic role of these species in the food web of the basin can be obtained from these data. At an ecosystem level, this information is essential to evaluate the possible consequences of the decline or recovery of the population of these exploited species.

Potential zoonotic agents in sea turtles: Chlamydia species and Listeria monocytogenes

Abstract Background Sea turtles are well recognized sentinels of marine environment as well as carrier of pathogens and contaminants. Chlamydial species have been described in reptiles, but scarce data regarding sea turtles are available in literature (Pace et al., 2022). Hitherto, only one case of listeriosis has been described in marine reptiles (Di Renzo et al., 2022). This study reports the detection of Chlamydia species and Listeria monocytogenes in loggerhead sea turtles (Caretta caretta), suggesting the role of these animals as carriers of potential zoonotic agents. Methods In 2022, a total of 11 sea turtles found stranded along Emilia-Romagna coast, Northwestern Adriatic Sea, were subjected to post mortem investigation. Cloacal swabs were collected from 10 of the investigated animals and screened for Chlamydiaceae family by qPCR targeting 23S rRNA gene, followed by confirmation via 16S rRNA fragment sequencing. For positive samples, Chlamydia species identification was performed by species-specific qPCR for C. abortus, C. pneumoniae, C. pecorum, C. psittaci. One subject showed internal organs disseminated with multiple nodular lesions that were sampled for histopathology analyses, alongside microbiological examination. The cultured isolates were identified by MALDI-TOF (MALDI Biotyper; Bruker Daltonics Inc). Results In six out of 10 cloacal swabs Chlamydiaceae DNA was demonstrated by qPCR and confirmed by sequencing of 16S rRNA, but species identification was not achieved. In the turtle with nodular lesions, histopathology revealed the presence of granulomas: the Ziehl-Neelsen stain was negative for acid-fast organisms. L. monocytogenes was isolated from heart and liver and listeriosis was diagnosed. Conclusions The results highlight how sea turtles can be carriers, symptomatic or not, of pathogens relevant for public health. Given the zoonotic potential of these microorganisms, particular precautions are recommended especially for professionals handling these animals. Key messages • Sea turtles can play an active role as carriers of possibly pathogenetic microorganisms. • Further studies of molecular identification of Chlamydia spp. from sea turtles are needed in atypical strains.

Saxitoxin hazard! Detection of toxic algae in molluscs breeding areas in North-Western Adriatic Sea

Abstract Background Saxitoxin (SXT) can cause the paralytic shellfish poisoning (PSP) with severe impacts on both human health and marine ecosystems. Dinoflagellates are the major marine producers of STX and other variety of secondary toxic metabolites that can gather in molluscs becoming a risk for consumers’ poisoning. The aim of this work was to investigate the presence of the main algal species producing SXT in an area intended for molluscs breeding. Methods During 2020-2023, 40 seawater samples were collected from two macro-areas in the Adriatic Sea (North-Western) at different distances from the coast. After water filtration, DNA was extracted (DNeasy PLANT Mini Kit) and analysed with Real Time PCR for Alexandrium minutum and Gymnodinium catenatum detection. The possible ability to produce SXT was confirmed by sxt4A gene detection. Molecular results were compared with the microscopy gold-standard method. Results A. minutum was detected in 62.5% (CI 95% 0.47-0.75) of the samples, with 84% (CI 95% 0.65-0.94) of them possibly producing SXT. G. catenatum was found in 95% (CI 95% 0.83-0.99) of samples, with 73.7% (CI 95% 0.58-0.85) of them presenting STX gene. By microscopy, only Alexandrium spp. were identified without successful species identification. No other saxitoxin-producing genera or species were observed. Conclusions Our results underlined that A. minutum and G. catenatum can play an important role in the production of SXT, confirming their harmful presence in the areas intended for molluscs breeding. Microscopic identification can lead to an underestimation of the presence of potentially toxic algal species, stressing the relevance of improving molecular tools also in this field. These findings highlighted the importance of reporting and monitoring toxic algae presence, given the saxitoxin impact for food safety, and its significance for public health. Key messages • Saxitoxin-producing algae detection through molecular methods in molluscs breeding areas may represent an early warning useful to improve food safety and human health. • Harmful algal monitoring can improve water management in a One Health perspective.

RNA/DNA ratios as estimate of metabolic and functional traits in diatom species from the northwestern Adriatic Sea

Abstract Different phytoplankton biomass estimations can provide information about abundance variation, but they are not able to describe the metabolic activity of species or groups within assemblages. Conversely, molecular traits are key for the metabolic dynamics in pelagic ecosystems. To investigate if the RNA/DNA and taxon-specific 18S ribosomal RNA (rRNA)/ribosomal DNA (rDNA) ratios could be used to assess and be indicators of metabolic activity in marine phytoplankton species, two Adriatic diatom species, Chaetoceros socialis and Skeletonema marinoi, were studied. Significant correlations between abundance, chlorophyll a, carbon content and proteins were found in individual and co-cultured growth experiments (from rs = 0.570 to rs = 0.986, P &amp;lt; 0.001). The biomass trend followed a logistic curve without providing additional information regarding diatom metabolic activity. In both experiments, the RNA/DNA and taxon-specific 18S rRNA/rDNA ratios of C. socialis and S. marinoi showed maximum values at the beginning of the growth phase, i.e as 23.2 ± 1.5 and 15.3 ± 0.8, and 16.2 ± 1.6 and 30.1 ± 5.4 after 2 and 6 days, respectively, in individual cultures, with a subsequent significant decrease in these values for both species in individual and co-culture experiments. Our results showed that these molecular rRNA/rDNA ratios expressed an activation of metabolism before the abundance increases, even in the presence of interspecific interaction between C. socialis and S. marinoi.

Balaenophilus manatorum in Debilitated and Bycatch-Derived Loggerhead Sea Turtles Caretta caretta from Northwestern Adriatic Sea.

Balenophilus manatorum (Copepoda: Harpaticoida) is one of the few components of the epibiontic fauna of Caretta caretta that show a "true" parasitic association with their host. From rrosive to ulcerative cutaneous lesions may seldom appear as a consequence of the copepod feeding on keratin on turtles' skin. Debilitating Turtle Syndrome (DTS) is the final outcome of a chronic insufficient assumption of nutrients, generally occurring with the impairment of immune functions and high epibiota burdens. In this survey, the presence of B. manatorum in C. caretta from the Northwestern Adriatic Sea was investigated and the relation between infection indices and the co-occurrence of DTS was studied. Clinical examination was performed at the time of rescue, including routine hematological assessment; external parasites were isolated mechanically from turtles' skin and morphologically identified through observation with an optic microscope and SEM. Ten turtles were classified as affected by DTS, all of them being small juveniles with typical clinical and clinicopathological presentation. A higher prevalence, abundance, and density of infection were found in turtles affected by the syndrome. The presence of massive skin coverage by the burrowing barnacle Pletylepas hexastylos prevented a proper evaluation of the pathology associated with B. manatorum in turtles affected by DTS. In any event, eventual skin damages caused by the parasite may represent a port of entry for secondary infections in such immunocompromised animals. Therefore, infection by B. manatorum should not go overlooked in debilitated turtles and should be opportunely treated.

Seasonal dynamics of the microbiome-host response to pharmaceuticals and pesticides in Mytilus galloprovincialis farmed in the Northwestern Adriatic Sea

Marine mussels, especially Mytilus galloprovincialis, are well-established sentinel species, being naturally resistant to the exposure to multiple xenobiotics of natural and anthropogenic origin. Even if the response to multiple xenobiotic exposure is well known at the host level, the role of the mussel-associated microbiome in the animal response to environmental pollution is poorly explored, despite its potential in xenobiotic detoxification and its important role in host development, protection, and adaptation. Here, we characterized the microbiome-host integrative response of M. galloprovincialis in a real-world setting, involving exposure to a complex pattern of emerging pollutants, as occurs in the Northwestern Adriatic Sea. A total of 387 mussel individuals from 3 commercial farms, spanning about 200 km along the Northwestern Adriatic coast, and in 3 different seasons, were collected. Multiresidue analysis (for quantitative xenobiotic determination), transcriptomics (for host physiological response), and metagenomics (for host-associated microbial taxonomical and functional features) analyses were performed on the digestive glands. According to our findings, M. galloprovincialis responds to the presence of the complex pattern of multiple emerging pollutants – including the antibiotics sulfamethoxazole, erythromycin, and tetracycline, the herbicides atrazine and metolachlor, and the insecticide N,N-diethyl-m-toluamide – integrating host defense mechanisms, e.g., through upregulation of transcripts involved in animal metabolic activity, and microbiome-mediated detoxification functions, including microbial functionalities involved in multidrug or tetracycline resistance. Overall, our data highlight the importance of the mussel-associated microbiome as a strategic player for the orchestration of resistance to the multixenobiotic exposure at the holobiont level, providing strategic functionalities for the detoxification of multiple xenobiotic substances, as occurring in real world exposure settings. Complementing the host with microbiome-dependent xenobiotic degradative and resistance genes, the M. galloprovincialis digestive gland associated microbiome can have an important role in the detoxification of emerging pollutants in a context of high anthropogenic pressure, supporting the relevance of mussel systems as potential animal-based bioremediation tool.

Screening, classification, capacity estimation and reservoir modelling of potential CO2 geological storage sites in the NW Adriatic Sea, Italy

In Italy, the central-northern Apennines and Adriatic Sea domains have been identified as potential CO2 storage areas. Although capacity estimates have been undertaken at a regional scale, more detailed research is required to reduce uncertainty. The present study helps address this gap by conducting a detailed screening of a representative area in the north-western Adriatic Sea for suitable CCS sites, using an extensive dataset composed of both public and private seismic and borehole data. Work included selecting suitable sites based on proposed selection criteria, calculating their theoretical and effective storage capacities applying a probabilistic approach, and then performing dynamic flow modelling on one of the selected sites that is representative of fractured carbonate reservoirs. Based on the screening results, a total of 21 out of 38 structures were selected as having the required characteristics suitable for CO2 storage. As expected, the clastic rock reservoirs have the greatest potential capacity, although some fractured carbonate reservoirs did yield important volumes due to their dual porosity / permeability characteristics. Modelling of one such site highlighted the complex interplay between primary and secondary porosity / permeability on plume migration and capacity estimation. Our results highlight the need to integrate analytical calculations with dynamic simulations for more detailed, site-specific studies to improve the estimates of CO2 storage capacity.

Understanding the Role of Macroalgal Complexity and Allelochemicals Production in Invasive and Non-Invasive Macroalgae in the North-Western Adriatic Sea: Effect on the Associated Communities

Highly diverse microphyto and meiobenthic communities are associated with large-sized marine macroalgae. Both morphological traits and allelochemical responses of macroalgae affect the composition of these communities, but the relative importance of these factors remains incompletely understood. In this study we investigated the microphytobenthic and meiobenthic communities associated with some native macroalgae and a non-indigenous species (Sargassum muticum) of the north-western Adriatic Sea. These seaweeds were sampled in two coastal sites subjected to different impacts. The possible effects of the structural complexity of the macroalgae and the potential role of allelochemicals (specifically polyunsaturated aldehydes, PUAs) on the associated communities were examined using univariate and multivariate analyses. The results indicate that distinct assemblages were associated with the macroalgae collected at the two different sites. Differences in microphytobenthic communities could be ascribed to differences in the macroalgal morphological traits and in their PUAs production. Conversely, variation of the meiobenthic community seemed to be related mainly to differences in the macroalgal communities at the two sites. This apparent inconsistency between the two analyzed communities suggests that microphytobenthos and meiofauna were differently shaped by the environmental habitat provided by macroalgae in the two sites, that are subjected to different environmental conditions and human activities. Overall, these results indicate that interactions between organisms belonging to different trophic groups (e.g., microphytobenthos and meiofauna) should be investigated in detail to better understand the global role of macroalgae as habitat formers on coastal ecosystems, especially in the case of large-sized introduced species.

A phytoplankton time series in the Northwestern Adriatic Sea: Structure and dynamics of the assemblages in a coastal ecosystem

Phytoplankton assemblage structure was analyzed based on time series data (2008–2019) together with environmental variables in two coastal sites in the Northwestern Adriatic Sea. The main component of phytoplankton assemblage was the diatom group. Distinct seasonal and inter annual variations in the presence of taxa were observed within the phytoplankton assemblage over the study period. Mainly four taxa showed a non-random pattern in the binary time series, such as three diatoms Skeletonema marinoi, Thalassionema nitzschioides and Dactyliosolen fragilissimus, and undetermined Dinophyceae. S. marinoi was more frequent in winter and early spring, whereas T. nitzschioides showed an opposite pattern, being more frequent in late spring and summer. In both cases, deviation from randomness was caused by a clear and almost stationary annual cycle. On the contrary, deviation from randomness depended on the long-term trend of D. fragilissimus time series, as this diatom showed an increasing frequency of occurrence since 2016. A clear phytoplankton assemblage structure affected by seasonal and environmental factors was observed. This was very evident for representative specie (i.e., S. marinoi associated with colder and rich nutrient waters or Heterocapsa niei and T. nitzschioides associated with high temperature and low nutrient conditions) and other species associated with various environmental parameters. Furthermore, the analysis of the association among phytoplankton taxa showed a partial and varied pattern. Our results highlight that phytoplankton time series showed changes in assemblage structure exhibiting a regular 12-month period affected by environmental factors. The long time series observations are important to understand the phytoplankton assemblage structure in relation to environmental changes and human pressures, crucial to achieving the Good Environmental Status in compliance to environmental directives.

Microbiome network in the pelagic and benthic offshore systems of the northern Adriatic Sea (Mediterranean Sea)

Because of their recognized global importance, there is now the urgent need to map diversity and distribution patterns of marine microbial communities. Even if available studies provided some advances in the understanding the biogeographical patterns of marine microbiomes at the global scale, their degree of plasticity at the local scale it is still underexplored, and functional implications still need to be dissected. In this scenario here we provide a synoptical study on the microbiomes of the water column and surface sediments from 19 sites in a 130 km2 area located 13.5 km afar from the coast in the North-Western Adriatic Sea (Italy), providing the finest-scale mapping of marine microbiomes in the Mediterranean Sea. Pelagic and benthic microbiomes in the study area showed sector specific-patterns and distinct assemblage structures, corresponding to specific variations in the microbiome network structure. While maintaining a balanced structure in terms of potential ecosystem services (e.g., hydrocarbon degradation and nutrient cycling), sector-specific patterns of over-abundant modules—and taxa—were defined, with the South sector (the closest to the coast) characterized by microbial groups of terrestrial origins, both in the pelagic and the benthic realms. By the granular assessment of the marine microbiome changes at the local scale, we have been able to describe, to our knowledge at the first time, the integration of terrestrial microorganisms in the marine microbiome networks, as a possible natural process characterizing eutrophic coastal area. This raises the question about the biological threshold for terrestrial microorganisms to be admitted in the marine microbiome networks, without altering the ecological balance.

Detection of Human and Fish Viruses in Marine Gastropods.

Simple SummaryMollusca is one of the largest phyla in the animal kingdom that includes more than 100,000 existing species living in aquatic and terrestrial habitats. Within this phylum, marine molluscs are considered an important resource for fisheries, and gastropods represent 2% of marine molluscs fished worldwide. Similar to bivalves, gastropods are susceptible to environmental contamination, and they are able to accumulate microorganisms. However, despite their economic importance, only few studies have focused on the monitoring of viral contamination in their tissues and their possible role as carriers. In this study, the presence of human pathogenic viruses such as hepatitis A virus, but not noroviruses, different to the situation in bivalve molluscs, was found in gastropods. This finding suggests a low risk of food-borne viral infections for gastropod consumers. Furthermore, one of the most impactful pathogens for marine aquaculture, nervous necrosis virus (NNV), was detected in gastropods. However, the animal tissues examined did not show any histological changes, suggesting the absence of a pathogenic effect of NNV in the analyzed gastropods.Marine gastropods represent a major food source for higher trophic levels and an important source of animal protein for humans. Like bivalve molluscs, gastropods can accumulate several types of contaminants; however, the bioaccumulation of microorganisms, particularly viruses, has been poorly investigated in these animals. This study focused on gastropods (Tritia mutabilis, Bolinus brandaris and Rapana venosa) collected during the fishing season from 2017 to 2021 in the north-western Adriatic Sea, and on clams (Ruditapes philippinarum) harvested in the same geographical area, in order to evaluate the presence of human and fish viruses in their tissues. A virological investigation was carried out on the digestive gland using molecular methods. The presence of hepatitis A virus was detected in one sample, whereas noroviruses were not present in the investigated specimens. Regarding fish viruses, it was possible to detect the presence of nervous necrosis virus (NNV) in 26.5% of the analyzed gastropods; however, the histological examination did not show any pathological changes in the nervous tissue in both NNV-positive and -negative batches. As a whole, the investigated gastropods showed the ability to bioaccumulate viruses; however, lower contamination by human viruses compared to bivalve molluscs was pointed out, posing a minor concern to human health.

Carbon accumulation and storage in a temperate coastal lagoon under the influence of recent climate change (Northwestern Adriatic Sea)

Pialassa Baiona is a shallow temperate coastal lagoon influenced by a variety of factors, including regional climate change and local anthropogenic disturbances. To better understand how these factors influenced modern organic carbon (OC) sources and accumulation rates, we measured OC as well as stable carbon isotopes (δ13C) in 210Pb-dated sediments within a vegetated saltmarsh habitat and a human impacted habitat. Relative Sea Level (RSL) at the nearby tide gauge station data and four different Sea Surface Temperature (SST) data sets were analyzed starting from 1900 to assess the potential effect of sea ingression and warming on the coastal lagoon sedimentary processes. The source contribution calculated from the MixSIAR Bayesian model revealed a mixed composition of sedimentary OC, dominated by an increase in marine-derived OC after the 1950s, matching with a decrease from autochthonous saltmarsh vegetation (Juncus spp.) in the saltmarsh habitat, and from riverine/estuarine-derived OC in the impacted habitat. RSL rise in the area (8.7 ± 0.5 mm yr−1 in the period 1900–2014) has been mainly driven by the land subsidence, especially during the central decades of the last century, enhancing the sea ingression into the lagoon. RSL rise influenced changes in sedimentary OC sources and accumulation at different level within the two habitats from the 1950s onward; conversely, no direct effect of SST was detected.

Long-term dynamics of annual and seasonal physical and biogeochemical properties: Role of minor river discharges in the North-western Adriatic coast

Dynamics of the physical and biogeochemical properties in a temperate coastal area in the north-western Adriatic Sea were analyzed. Multi-year (1997–2019) continuous observations allowed assessing their trends at two sites directly influenced by the discharges of two minor rivers as well as by human activities and climate change. Statistical models were applied to investigate the temporal variability and trends of seawater temperature, salinity, chlorophyll a, nutrients, river discharges and precipitations. The analysis highlighted a role for the minor river inputs and for ecological processes on interannual and seasonal biogeochemical dynamics. We found a significant trend toward more oligotrophic conditions; in particular, chlorophyll a exhibited a long-term decline (−1.38% year−1 and - 1.5% year−1 at the two Foglia and Metauro river transects, respectively) that was largely determined by low phosphate and nitrate seawater concentrations as a result of a significant reduction in the phosphate and nitrate loadings of the two minor rivers (respectively mean values of −4.65% year−1 and -2.65% year−1). In contrast, salinity showed a long-term decrease of −0.24% year−1 and -0.19% year−1 at Foglia and Metauro, respectively, corresponding to a significant increase of the freshwater discharges of the two minor rivers (+1.86% and +1.57% year−1 at Foglia and Metauro, respectively) possibly due to precipitations. Data analysis highlighted the conditions of temperate coastal areas affected by freshwater discharges. Nutrient load management and climate conditions such as precipitation regimes appear to be the main factors driving physical and biogeochemical dynamics in the north-western Adriatic Sea.