HAS THE RECOLONIZATION OF THE PO PLAIN BEGUN? UPDATES REGARDING THE PRESENCE OF THE EURASIAN OTTER (Lutra lutra) IN NORTH-EASTERN ITALY

Widespread in Italy in the early 1900s, the Eurasian otter subsequently underwent a dramatic decline that led to its local extinction in many administrative regions, with the exception of a small residual nucleus in southern Italy. For a few years now, the Austrian and Slovenian populations adjacent to north-eastern Italy have been increasing sharply, leading to a recolonization of the area by the species. During 2020, in Friuli Venezia Giulia, surveys of signs of presence were carried out in 48 grid cells (10 x 10 km) to update information on the species’ local distribution. The following monitoring methods were used: monitoring beneath bridges combined with transects along water courses. 17 grid cells tested positive for the presence of the species, and currently, the otter appears widely distributed in Friuli Venezia Giulia along the main waterways of the Eastern Alps and Prealps, and in some areas overlooking the plain of the Tagliamento and the transborder Isonzo-Soča basin, both included in the Po plain. These constitute the first observations of the species for more than 50 years. Compared to previous studies, 13 new grid cells involving the presence of otters were identified, including in lowland areas, suggesting a progressive expansion from the mountain ranges towards the Po-Venetian Plain. This represents, a spur to expand research and implement new studies to improve levels of knowledge about and the consequent protection of the species. Finally, the integration of transects along riverbanks to monitoring beneath bridges, allowed us both to collect numerous observation and to compare our results with previous studies

Energy Densities of Brown Trout (Salmo trutta) and Its Main Prey Items in an Alpine Stream of the Slizza Basin (Northwest Italy)

ABSTRACT In the present study, energy densities of 80 adult brown trout (Salmo trutta), seasonally sampled in an alpine stream in the eastern Alps and energy densities of their main prey items, were determined. The energy density (J/g wet mass) and dry weight content (%) of fish were highly correlated (p<0.00 1) and averaged 5, 611.6 ± 857.9 J/g wet mass and 25.3 ± 2.1% dry weight, respectively. Energy density values were significantly higher in fish sampled in spring than in other seasons. No major changes in the energy content were observed due to age or sex. Macroinvertebrates. particularly Ephemeroptera and Diptera, were the major food source of brown trout in the sampled area. Their gross energy content varied within a wide range of values (1, 654–5, 110 J/g wet weight), depending on the taxa and family or genus within a given taxon

Assessment of Biological and Sanitary Condition of Alien Fish from a High-Mountain Lake (Cottian Alps)

This study aimed to assess the biological and sanitary conditions of alien fish in a high-mountain lake (Balma Lake) located in the Cottian Alps. A single fish sampling session (August 2018) using gillnets collected 90 specimens of brook trout (Salvelinus fontinalis). Sex and age were determined (59 females and 31 males, age class 0+ to 4+). Regression analysis showed no difference in total weight and total length between males and females (ANCOVA: F = 0.453; p = 0.954). The mean condition factor (Kmean) decreased with increasing age for males and females. Terrestrial insects were the main prey found in the fish stomachs. The parasitological exam was negative, and the bacteriological exam was positive for Carnobacterium maltaromaticum and C. divergens in 33% of specimens. The total mercury, cadmium, and lead concentration in muscle tissue was within the maximum limit established by the European Commission for human consumption. The brook trout population was found to be well structured; these findings may help local administrations in the implementation of eradication measures

The unusual isolation of carnobacteria in eyes of healthy salmonids in high‑mountain lakes

Carnobacteria are common bacteria in cold and temperate environments; they are also reported during fsh mortality events. In a previous study, carnobacteria were isolated from the eyes of healthy wild salmonids from a high-mountain lake. To better understand these fndings, salmonids were captured from three high-mountain lakes (Lower and Upper Balma Lake, Rouen Lake; northwest Italy) during August 2019 and subjected to bacteriological and histological examination. Although all were healthy, 8.7% (Lower Balma Lake), 24% (Upper Balma Lake), and 32.6% (Rouen Lake) were positive for carnobacteria colonization of the eyes. A Trojan-horse efect was hypothesized to explain carnobacteria isolation in the eye. This immune-escaping macrophage-mediated mechanism has been identifed in other Gram-positive bacteria. Biochemical, molecular, and phylogenetic analysis were carried out on isolated bacteria (Carnobacterium maltaromaticum and C. divergens). Based on previous references for carnobacteria isolated from fsh, C. maltaromaticum strains were tested for the pisA precursor gene of the bacteriocin piscicolin 126. Carnobacterium maltaromaticum strains were found to display genotypic heterogeneity and a low percentage of pisA positive amplifcation. Features of geomorphology, geographic isolation, and microbiota common to the three lakes are thought to be possibly related to our fndings. Moreover, terrestrial insects collected from the lake shoreline and the stomach contents were screened for the presence of carnobacteria. The salmonids in these high-mountain environments feed mainly on terrestrial insects, which are considered possible vectors for carnobacteria that might catabolize the exoskeleton chitin. All insects tested negative for carnobacteria, but as a small number of samples were analyzed, their role as possible vectors of infection cannot be excluded. Further studies are needed to corroborate our research hypothesis

Relationship between the prevalence of Dibothriocephalus latus(Cestoda: Diphyllobothriidea) and the load of Escherichia coli: New findings in a neglected fish-borne parasitic zoonosis

The sub-Alpine lakes of Switzerland, Italy and France have long been reported as an endemic area of diphyllobothriosis, a parasitic zoonosis aused by Dibothriocephalus latus. With this study, we explored the hypothesis for a relationship between the prevalence of D. latus in Perca fluviatilis and the Escherichia coli load in lake water. To do this, we identified eleven sampling sites in three areas (north, centre and south) of Lake Iseo (north Italy) to determine E. coli load and the prevalence of D. latus in P. fluviatilis. Prevalence and 95% confidence interval (CI) of D. latus infestation ranged from 0% (95% CI: 0.71–0.0) in Sarnico (southern area) to 20% (95% CI: 33.0–11.2) in Pisogne (northern area). There were significant differences in prevalence be-tween the sites (χ2= 31.12; p- value= .0006) and in E. coli load (Kruskal–Wallis test; p- value= .0005). There was decreasing gradient of E. coli load and prevalence of D. latus infestation from north to south. A significant positive correlation (r= .881; p- value= .003) was found between E. coli load and prevalence of D. latus. Also, linear regression showed a significant relationship between E. coli load and prevalence of infestation (R2= .775). Our findings offer an explanation for the link between E. coliload in water and D. latus prevalence. The potential factors in this link are the ef-ficiency of the local wastewater treatment plant, the bathymetric profile of the lake and the life cycle of D. latus, which is mainly affected by light and water temperature.KEYWORDSItaly, Lake Iseo, Perca fluviatilis, prevalence of infestation, wastewater treatment plant, the bathymetric profile of the lake and the life cycle of D. latus, which is mainly affected by light and water temperature

Indagini genetiche su Salmo [trutta] marmoratus (Cuvier, 1817) a supporto delle popolazioni naturali: risultati sulladistribuzione nel Friuli - Venezia Giulia

Atti del Convegno Salmonidi Alpini Gestione delle popolazioni autoctone e qualit\ue0 dei ripopolamenti, Rovereto 19 ottobre 200