Suchergebnisse

AbstractThe broadly utilized biocide triclosan (TCS) is continuously discharged in water compartments worldwide, where it is detected at concentrations of ng-µg/L. Given its lipophilicity and bioaccumulation, TCS is considered potentially harmful to human and environmental health and also as a potential endocrine disruptor (ED) in different species. In aquatic organisms, TCS can induce a variety of effects: however, little information is available on its possible impact on invertebrate development. Early larval stages of the marine bivalve Mytilus galloprovincialis have been shown to be sensitive to environmental concentrations of a number of emerging contaminants, including EDs. In this work, the effects of TCS were first evaluated in the 48 h larval assay in a wide concentration range (0.001–1,000 μg/L). TCS significantly affected normal development of D-veligers (LOEC = 0.1 μg/L; EC50 = 236.1 μg/L). At selected concentrations, the mechanism of action of TCS was investigated. TCS modulated transcription of different genes involved in shell mineralization, endocrine signaling, ceramide metabolism, and biotransformation, depending on larval stage (24 and 48 h post-fertilization-hpf) and concentration (1 and 10 μg/L). At 48 hpf and 10 μg/L TCS, calcein staining revealed alterations in CaCO3 deposition, and polarized light microscopy showed the absence of shell birefringence due to the mineralized phase. Observations by scanning electron microscopy highlighted a variety of defects in shell formation from concentrations as low as 0.1 μg/L. The results indicate that TCS, at environmental exposure levels, can act as a developmental disruptor in early mussel larvae mainly by interfering with the processes of biomineralization.

Infectious agents such as the bacteria Vibrio aestuarianus or Ostreid herpesvirus 1 have been repeatedly associated with dramatic disease outbreaks of Crassostrea gigas beds in Europe. Beside roles played by these pathogens, microbial infections in C. gigas may derive from the contribution of a larger number of microorganisms than previously thought, according to an emerging view supporting the polymicrobial nature of bivalve diseases. In this study, the microbial communities associated with a large number of C. gigas samples collected during recurrent mortality episodes at different European sites were investigated by real‐time PCR and 16SrRNA gene‐based microbial profiling. A new target enrichment next‐generation sequencing protocol for selective capturing of 884 phylogenetic and virulence markers of the potential microbial pathogenic community in oyster tissue was developed allowing high taxonomic resolution analysis of the bivalve pathobiota. Comparative analysis of contrasting C. gigas samples conducted using these methods revealed that oyster experiencing mortality outbreaks displayed signs of microbiota disruption associated with the presence of previously undetected potential pathogenic microbial species mostly belonging to genus Vibrio and Arcobacter. The role of these species and their consortia should be targeted by future studies aiming to shed light on mechanisms underlying polymicrobial infections in C. gigas. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under the EU project H2020 VIVALDI Grant No. 678589. We thank all the producers and people helping with sampling collection at the farming sites. We also thank the Ifremer ECOSCOPA network for producing and maintaining the oysters in the Bay of Brest. ; SI

AbstractThe European Interreg Italy–France 2014–2020 Maritime Project SPlasH! (Stop to Plastics in H2O!) focused on the study of microplastics (MPs) in the marine port environment to evaluate their presence, abundance, and mechanisms of diffusion to the open sea. In the framework of this project, a worldwide review of 74 studies was carried out, providing an overview of MP investigation techniques, focusing on sampling strategies, laboratory methodologies, and identification of MPs collected in seawater, and specifically evaluating their applicability to the marine port environment. Nets were the most commonly used device for MP surface sampling, but their use can be difficult in narrow spaces within the port basins, and they must be coupled to discrete sampling devices to cover all port basins. In the laboratory, density separation (NaCl, ZnCl2, NaI, sodium lauryl sulfate (SLS)), filtration (polycarbonate, polyamide, glass, cellulose, ANOPORE inorganic membrane filters), sieving, visual sorting, and digestion methods (acidic, enzymatic, alkaline, oxidative) were used to separate MPs from seawater. Digestion becomes essential with water samples with great inorganic and organic loads as deriving from a port. Although many studies are based only on visual MP identification under a microscope, analytical identification techniques unequivocally determine the particle nature and the identity of the plastic polymers and are necessary to validate the visual sorting of MPs. Fourier-transform infrared spectroscopy (FTIR) is the most used analytical identification technique.