A stratified compartmental model for the transmission of Sparicotyle chrysophrii (Platyhelminthes: Monogenea) in gilthead seabream (Sparus aurata) fish farms†.

The rapid development of intensive fish farming has been associated with the spreading of infectious diseases, pathogens and parasites. One such parasite is Sparicotyle chrysophrii (Platyhelminthes: Monogenea), which commonly infects cultured gilthead seabream (Sparus aurata)-a vital species in Mediterranean aquaculture. The parasite attaches to fish gills and can cause epizootics in sea cages with relevant consequences for fish health and associated economic losses for fish farmers. In this study, a novel stratified compartmental epidemiological model of S. chrysophrii transmission was developed and analysed. The model accounts for the temporal progression of the number of juvenile and adult parasites attached to each fish, as well as the abundance of eggs and oncomiracidia. We applied the model to data collected in a seabream farm, where the fish population and the number of adult parasites attached to fish gills were closely monitored in six different cages for 10 months. The model successfully replicated the temporal dynamics of the distribution of the parasite abundance within fish hosts and simulated the effects of environmental factors, such as water temperature, on the transmission dynamics. The findings highlight the potential of modelling tools for farming management, aiding in the prevention and control of S. chrysophrii infections in Mediterranean aquaculture.

On the delay between water temperature and invertebrate community response to warming climate.

We evaluated the effect of global warming on invertebrate communities at high altitudes using data from the Careser system. We procured data on air temperature, which was obtained over 50 years at altitudes above 2600 m a.s.l., and data on water temperature, which was available for approximately 30 years. We sampled thrice in the past 20 years (2001, 2014, 2018) at three sampling sites (CR0-metakryal, CR1-hypokryal, CR2-glacio-rhithral) of the Careser glacier-fed stream and its main non-glacial tributary (CR1bis-krenal). Warmer climates were observed in the last decade compared to the 1980s, with a mean maximum summer air temperature (mTmax) increase of 1.7 °C at 2642 m a.s.l. and 1.8 °C at 2858 m a.s.l. Compared to air temperatures, the rise in water temperature was delayed by approximately 20 years; water mTmax started to increase in 2003, reaching 8.1 °C at 2642 m a.s.l. and 2.4 °C at 2858 m a.s.l in the year 2020. The invertebrate community exhibited a delayed response approximately 13 years from the water warming; there was a sequential increase in the number of taxa, Shannon diversity, and after 17 years, functional diversity. In the kryal sites, taxonomical and functional diversity changed more consistently than in the glacio-rhithral site in the same period, due to the arrival of taxa that were previously absent upstream and bearers of entirely new traits. Progressive taxonomical homogenisation was evident with decreasing glacial influence, mainly between glacio-rhithral and krenal sites. The numbers of Diamesa steinboecki, an insect that was adapted to the cold, declined in summer (water mTmax >6 °C and air mTmax >12 °C). This study highlights the mode and time of response of stream invertebrate communities to global warming in alpine streams and provides guidelines for analysing changes in the stream invertebrate communities of other glacial systems in alpine regions.

Permafrost dynamics and the risk of anthrax transmission: a modelling study.

A recent outbreak of anthrax disease, severely affecting reindeer herds in Siberia, has been reportedly associated to the presence of infected carcasses or spores released from the active layer over permafrost, which is thawing and thickening at increasing rates, thus underlying the re-emerging nature of this pathogen in the Arctic region because of warming temperatures. Anthrax is a global zoonotic and epizootic disease, with a high case-fatality ratio in infected animals. Its transmission is mediated by environmental contamination through highly resistant spores which can persist in the soil for several decades. Here we develop and analyze a new epidemiological model for anthrax transmission that is specifically tailored to the Arctic environmental conditions. The model describes transmission dynamics including also herding practices (e.g. seasonal grazing) and the role of the active layer over permafrost acting as a long-term storage of spores that could be viable for disease transmission during thawing periods. Model dynamics are investigated through linear stability analysis, Floquet theory for periodically forced systems, and a series of simulations with realistic forcings. Results show how the temporal variability of grazing and active layer thawing may influence the dynamics of anthrax disease and, specifically, favor sustained pathogen transmission. Particularly warm years, favoring deep active layers, are shown to be associated with an increase risk of anthrax outbreaks, and may also foster infections in the following years. Our results enable preliminary insights into measures (e.g. changes in herding practice) that may be adopted to decrease the risk of infection and lay the basis to possibly establish optimal procedures for preventing transmission; furthermore, they elicit the need of further investigations and observation campaigns focused on anthrax dynamics in the Arctic environment.

Analysis of 52 pesticides in fresh fish muscle by QuEChERS extraction followed by LC-MS/MS determination.

Pesticide pollution in water has been well described; however, little is known on pesticide accumulation by aquatic organisms, and to date, most studies in this line have been focused on persistent organochlorine pesticides. For this reason, a method based on QuEChERS extraction and subsequent liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis has been developed and validated for the determination of 52 medium to highly polar pesticides in fresh fish muscle. Target pesticides were selected on the basis of use and occurrence in surface waters. Quantification is carried out following an isotope dilution approach. The method developed is satisfactory in terms of accuracy (relative recoveries between 71 and 120%), precision (relative standard deviations below 21%) and sensitivity (limits of determination in the pg/g or low ng/g f.w. range for most compounds). The application of the validated methodology to fish specimens collected from the Adige River (Italy) revealed the presence of trace levels of diazinon, dichlorvos and diuron, and measurable levels of metolachlor, quinoxyfen, irgarol, terbutryn, and acetamiprid, but in all cases at concentrations below the default maximum residue level of 10 ng/g established for pesticides not specifically regulated in fish intended for human consumption. Metolachlor and quinoxyfen were both the most ubiquitous and abundant pesticides, in agreement with their high potential for bioaccumulation. Both are toxic to aquatic organisms, and therefore, their potential effects on aquatic ecosystems should be further explored.

Contamination sources and distribution patterns of pharmaceuticals and personal care products in Alpine rivers strongly affected by tourism.

Knowledge regarding the impact of tourism on the emergence of pharmaceuticals and personal care products (PPCPs) in Alpine river waters is limited and scarce. Therefore, a study on the occurrence patterns and spatiotemporal variability of 105 PPCPs in an Alpine river basin located in the Trentino-Alto Adige region (North-Eastern Italy) has been conducted. We observed that the total concentration of analyzed PPCPs was generally higher in all sampling sites during winter than in the summer. The analysis of tourist data revealed that during both sampling campaigns the number of tourists was lower in the downstream sites in comparison with the upstream area of the basin (Val di Sole). Particularly, sampling sites located near important tourist resorts have shown the highest abundance of the PPCPs during winter, being analgesics/anti-inflammatories, antihypertensives and antibiotics the most abundant pharmaceutically active compounds (PhACs). Diclofenac showed the highest concentration amongst PhACs, reaching concentrations up to 675ngL-1 in the sampling site situated downstream of the Tonale wastewater treatment plant (WWTP). Antihypertensives were found at concentrations >300ngL-1, while antibiotics were quantified up to 196ngL-1, respectively. Amongst personal care products (PCPs), the most abundant compound was octyl-dimethyl-p-aminobenzoic acid (ODPABA) with concentrations reaching up to 748ngL-1 in the sampling site situated within the Rotaliana district. In general, concentrations and detection frequencies were higher in water than in the sediment samples. The most frequently detected PhACs in sediments from both sampling campaigns were antibiotics, while amongst PCPs in sediments, octocrylene (OC) showed the highest concentration in both sampling campaigns. As a result, this study highlights the potential impact of tourism on the water quality of the Alpine aquatic ecosystems.

Evaluation of genotoxic potential throughout the upper and middle stretches of Adige river basin.

In this study a comprehensive genotoxicological survey throughout the upper and middle stretches of Adige river basin is presented. The study was carried out at 7 sites located along the Adige main course and one the most significant tributaries, the Noce creek, both presenting different levels of pollution pressure. To give an insight into the nature of the genotoxic activity we employed the battery of prokaryotic and eukaryotic assays. Mutagenicity in water samples was evaluated by SOS/umuC test in Salmonella typhimurium TA1535/pSK1002. The level of DNA damage as a biomarker of exposure (comet assay) and biomarker of effect (micronucleus assay) and the level of oxidative stress as well (Fpg - modified comet assay) were studied in blood cells of Salmo cenerinus Nardo, 1847 and Salmo marmoratus Cuvier, 1829. Within the applied bioassays, comet assay showed the highest potential for discriminating the sampling sites which are under lesser extent of pressure (sampling sites 1-Barnes at Bresimo and 4-Noce downstream S. Giustina) from the sites under high pressure (sampling sites 5-Noce at Mezzolombardo and 6/7-Adige upstream and downstream municipality of Trento). Significant correlation between the standard and Fpg - modified comet assay indicated that oxidative stress could be a major contributor to observed DNA damage in collected specimens.

A review of hydrological and chemical stressors in the Adige catchment and its ecological status.

Quantifying the effects of multiple stressors on Alpine freshwater ecosystems is challenging, due to the lack of tailored field campaigns for the contemporaneous measurement of hydrological, chemical and ecological parameters. Conducting exhaustive field campaigns is costly and hence most of the activities so far have been performed addressing specific environmental issues. An accurate analysis of existing information is therefore useful and necessary, to identify stressors that may act in synergy and to design new field campaigns. We present an extended review of available studies and datasets concerning the hydrological, chemical and ecological status of the Adige, which is the second longest river and the third largest river basin in Italy. The most relevant stressors are discussed in the light of the information extracted from a large number of studies. The detailed analysis of these studies identified that hydrological alterations caused by hydropower production are the main source of stress for the freshwater ecosystems in the Adige catchment. However, concurrent effects with other stressors, such as the release of pollutants from waste water treatment plants or from agricultural and industrial activities, have not been explored at depth, so far. A wealth of available studies address a single stressor separately without exploring their concurrent effect. It is concluded that a combination of extended experimental field campaigns, focusing on the coupled effects of multiple stressors, and modeling activities is highly needed in order to quantify the impact of the multifaceted human pressures on freshwater ecosystems in the Adige river.