Use of the Zebra Mussel Dreissena polymorpha (Mollusca, Bivalvia) as a Bioindicator of Microplastics Pollution in Freshwater Ecosystems: A Case Study from Lake Iseo (North Italy)

The monitoring of microplastics pollution in freshwater environments trails behind its practice in marine ecosystems. We evaluated the use of the invasive zebra mussel (Dreissena polymorpha) as a potential bioindicator of microplastic litter in freshwater lakes. Samples were collected from three sites (Lovere, Costa Volpino, Castro) at the northern end of Lake Iseo (one of the major subalpine lakes in north Italy) and compared for water physicochemical parameters, biometrical features of zebra mussels, and microplastics items/specimens (color, shape, size, and chemical composition). We hypothesized that since a wastewater treatment plant (WWTP) on the Oglio River discharges into this area of the lake, the microplastics in D. polymorpha could be measured and compared in samples from the three sites at different distances from the WTP. There was no difference in the physicochemical water parameters and biometric features between the samples from the three sites, whereas there was a significant difference in items/specimen between the sites in decreasing order (mean \ub1 standard deviation): Costa Volpino (0.23 \ub1 0.43) > Lovere (0.07 \ub1 0.25) > Castro (0.03 \ub1 0.18). The chi-square test showed a significant difference in shape, color, and chemical composition frequency in the samples from the three sites. The chemical composition of the microplastics was polyethylene terephthalate (45%), nylon (20%), polypropylene (20%), polyamide resin (10%), and polyvinyl chloride (5%). Our data show that the amount of microplastics the zebra mussel accumulated was greater the closer the sampling site to the WWTP. Our findings suggest that the zebra mussel may provide a useful tool to monitor microplastics pollution in lakes

First Report of Clinostomum complanatum (Trematoda: Digenea) in European Perch (Perca fluviatilis) from an Italian Subalpine Lake: A Risk for Public Health?

Clinostomum complanatum, a digenean trematode of the Clinostomidae family, is a fish-borne zoonotic parasite responsible for Halzoun syndrome in humans and is transmitted through the consumption of raw or undercooked freshwater fish. Of the total of 112 specimens of European perch (Perca fluviatilis) sampled from a subalpine lake (Lake Endine) in North Italy in 2019, 21 (18.75%) tested positive for encysted metacercariae in the fillet. This study reports the first isolation of C. complanatum in P. fluviatilis and highlights the possible zoonotic risk for consumers, since P. fluviatilis is a food fish used in the traditional local cuisine

The Old and the New on Viral Diseases in Sturgeon

Although sturgeon production by aquaculture has increased worldwide, a major factor limiting its expansion are infectious diseases, although few data about viral diseases are available however. This review provides a rapid overview of viral agents detected and described to date. Following a general introduction on viral diseases are four sections arranged by virus classification: sturgeon nucleocytoplasmic large DNA viruses, herpesviruses, white sturgeon adenovirus 1, and other viruses. Molecular diagnosis is currently the best tool to detect viral diseases, since cell culture isolation is not yet applicable for the detection of most sturgeon viruses

Liver Lipid Accumulation in European Bullhead (Cottus cobio) from a High-Mountain Lake: An Adaptive Strategy to Survive the Adverse Winter Season

The hypothesis that liver lipid accumulation in fish is an adaptive strategy to survive the winter in the high-altitude environment was assessed in this study. During summer 2019, specimens of Cottus gobio were sampled in 15 watercourses of Friuli Venezia-Giulia Region (Italy) to verify if hepatic steatosis is or not normally present in the species. To do this, hepatic vacuolization was assessed by histology using a semiquantitative score. Furthermore, C. gobio were also captured during the ice-free season at Dimon Lake (1872 m a.s.l.) and But Stream (520 m a.s.l.) to compare the trend in lipid accumulation: water temperature, hepatosomatic index (HSI), gonadosomatic index (GSI), Fulton\u2019s condition factor (K), and lipid area percentage (lipid %) were measured monthly. Findings revealed that liver steatosis is rather common in C. gobio. However, the trend in lipid accumulation of this species diered between Dimon Lake and But Stream. Based on the HSI and the GSI, the reproductive cycles diered in fish from the two environments (April\u2013May in But Stream; May\u2013June in Dimon Lake). While K values remained unchanged in the But Stream specimens, significant changes were recorded for Dimon specimens. The increase in lipid % from July to August in the Dimon Lake specimens coincided with greater food availability. With the rapid drop in lake water temperature in October, the lipid % decreased due to slower metabolic rate and lipid utilization from liver stores. There was a slight decrease in lipid % in the But Stream specimens, indicating that lipids were not being accumulated. Introduced years ago, the Dimon Lake bullhead population has since adapted to the winter conditions at high elevation

Northward Spread of the Parrotfish Sparisoma cretense (Teleostei: Scaridae) in the Mediterranean Sea: An Update on Current Distribution with Two New Records from Sardinia

The parrotfish Sparisoma cretense, a marine species native to the eastern and southern coastal areas of the Mediterranean, has extended its distribution northward. Here, we provide an update on its distribution based on currently published data and two new records from the coastline of Sardinia, Italy (central-western Mediterranean). The survey methods were scuba diving and spearfishing: one specimen of S. cretense was caught along the Argentiera coastline (northwest Mediterranean) and the others were photographed in the Gulf of Orosei, Osalla Bay (central-eastern Mediterranean). A literature update, together with new records, documents the distribution of this species in the northernmost areas of the Mediterranean. Probably a result of global warming, the ongoing northward expansion of S. cretense highlights the need for sampling campaigns to obtain timely updates on population and distribution of this thermophilic species

Reply to Pavlik et al. Clinical Relevance and Environmental Prevalence of <i>Mycobacterium fortuitum</i> Group Members. Comment on “Mugetti et al. Gene Sequencing and Phylogenetic Analysis: Powerful Tools for an Improved Diagnosis of Fish Mycobacteriosis Caused by <i>Mycobacterium fortuitum</i> Group Members. <i>Microorganisms</i> 2021, <i>9</i>, 797”

We appreciate the valuable comment of Pavlik et al. [...

First Occurrence of Eustrongylides spp. (Nematoda: Dioctophymatidae) in a Subalpine Lake in Northwest Italy: New Data on Distribution and Host Range

The genus Eustrongylides includes nematodes that infect fish species and fish-eating birds inhabiting freshwater ecosystems. Nematodes belonging to the genus Eustrongylides are potentially pathogenic for humans; infection occurs after the consumption of raw or undercooked fish. In the two-year period 2019\u20132020, a total of 292 fish belonging to eight species were examined for the occurrence of Eustrongylides spp. from Lake San Michele, a small subalpine lake in northwest Italy. The prevalence of infestation was 18.3% in Lepomis gibbosus, 16.7% in Micropterus salmoides, and 10% in Perca fluviatilis. The other five fish species (Ameiurus melas, Ictalurus punctatus, Squalius cephalus, Carassius carassius, and Scardinius erythrophthalmus) were all negative for parasite presence. There were no significant differences in prevalence between the three fish species (Fisher\u2019s exact test; p = 0.744). The mean intensity of infestation ranged from 1 (M. salmoides and P. fluviatilis) to 1.15 (L. gibbosus), and the mean abundance ranged from 0.1 (P. fluviatilis) to 0.28 (L. gibbosus). There were significant differences in the infestation site between the four muscle quadrants (anterior ventral, anterior dorsal, posterior ventral, and posterior dorsal) and the visceral cavity (Kruskal\u2013Wallis test; p = 0.0008). The study findings advance our knowledge about the distribution and host range of this parasite in Italy