Camilla Della Torre

Freshwater mussels (Unionida) are key to the health of many freshwater systems through the ecosystem functions and services they provide, yet their populations are declining across the globe. To address these declines with appropriate conservation actions, it is necessary to apply informative tools for measuring and monitoring mussel health. To do this, a suite of biomarker methods has been applied to mussels. However, baseline biomarker measurements are often not available, no framework exists for the translation of these methods from research into routine mussel health monitoring and they are impractical for giving rapid measurements in the field due to the extensive time, expertise, cost and/or lab processing they require. Here, we developed a tool (the mussel Stress Tester, STer) to measure mussel valve closure strength as a proxy for condition. The STer is a specially designed pair of tongs with prongs that can bend when opening a mussel. The tongs give a numerical reading of this prong displacement (the STer value), which is indicative of the mussel's valve closure strength. During a field trial, we showed that measurements with the mussel STer were repeatable. We demonstrated the tool's applicability for assessing mussel condition by showing that STer value was positively associated with acetylcholinesterase activity, a well‐established bioindicator assay for stress. Taking measurements with the mussel STer requires little user training, minimal costs and only a few seconds per mussel. Thus, the STer can be applied rapidly in the field to provide estimations of mussel condition, which could be integrated into wider health assessments to inform appropriate conservation action. Additional work is required to assess whether use of the STer, and associated removal and handling of mussels, causes any long‐term harm to individuals. Even so, we envision the widespread application of this tool in rapid mussel health monitoring in the future.

This study presents the first evaluation of plastic particle contamination along a complete drinking water supply chain within the distribution system of Milan, Northern Italy. Fourteen grab water samples were collected from various points, including groundwater extraction, post-treatment stages, a public fountain, and ten household taps. Plastic particles were identified using µFTIR spectroscopy and characterized by polymer type, shape, size, and color. Overall, low concentrations of plastic particles were detected, ranging from 0.3 ± 0.5 particles/L in the accumulation tank to an average of 1.9 ± 1.4 particles/L in household tap water, with no significant increase observed along the supply chain. The entire data set was dominated by cellulose particles (76%), as plastics accounted for only 8%. Microplastics (1 µm–1 mm) were the most commonly detected (90%), while the remaining 10% were large microplastics (1–5 mm). Qualitatively, polyester fibers were the most prevalent particles identified. However, greater variability and higher concentrations were found in private residence samples, suggesting that internal plumbing systems may be a primary source of contamination. Estimated human exposure through this supply system, based on a current theoretical model, was minimal compared to global benchmarks. These findings highlight the necessity of integrating private distribution infrastructure into future regulatory frameworks to assist stakeholders in making informed decisions to mitigate potential plastic contamination.

Many taxa around the globe are threatened by often unexplained mass mortality events (MMEs), which can decimate populations and compromise key ecosystem functions. One example of a highly threatened taxon facing frequent MMEs is freshwater mussels (Unionida). There has been a recent increase in interest in understanding the causes of freshwater mussel MMEs, but standardised methodologies for how best to respond to them to facilitate diagnoses are unavailable. When an MME is observed, swift and appropriate sample collection is imperative owing to the transient nature of these phenomena. Here we provide structured guidance that will facilitate rapid and appropriate sampling of MMEs, using freshwater mussels as an example. We set out standardised procedures for sample collection, preparation and preservation. The procedures we outline will improve our capacity for diagnostic investigations of MMEs and other mortality events, not only in freshwater mussels but also across many other taxa. This, in turn, can inform appropriate management responses.

Oceans’ absorption of human‐related CO ₂ emissions leads to a process called ocean acidification (OA), consisting of the decrease of the seawater pH with negative consequences for many marine organisms. In this study, we investigate the microbial community of two species of polychaetes found in naturally acidified CO ₂ vents: the nereid Platynereis massiliensis complex and the syllid Syllis prolifera . Animals were collected in the CO ₂ vents of Castello Aragonese (Gulf of Naples, Ischia, Italy) in three zones at decreasing pH. For the analysis of the microbiome, the V3‐V4 hypervariable region of the 16S ribosomal RNA gene of 40 worm samples was sequenced on an Illumina MiSeq platform. No difference in the microbial alpha diversity of both species was highlighted. On the contrary, the microbial composition of worms collected in the site at normal pH was different from that of the individuals obtained from the sites at lower pH. This effect was evident also in samples from the site with a slight, but relevant, degree of acidification. Amplicon sequence variants showing a significant variation among the groups of samples collected from different pH zones were reported for both polychaetes, but no common trend of variation was observed. The present study deepens our knowledge about the composition of polychaete microbiome in marine naturally acidified sites. Our results stress the importance of future investigations about the connection between the variation of environmental and polychaete microbial communities induced by OA and about the effect of these variations on polychaete key biological and ecological traits.