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Freshwater mussels (Mollusca: Unionidae) play a crucial role in freshwater river environments where they live in multi-species aggregations and often serve as long-lived benthic ecosystem engineers. Many of these species are imperiled and it is imperative that we understand their basic needs to aid in the reestablishment and maintenance of mussel beds in rivers. In an effort to expand our knowledge of the diet of these organisms, five species of mussel were introduced into enclosed systems in two experiments. In the first, mussels were incubated in water from the Clinch River (Virginia, USA) and in the second, water from a manmade pond at the Commonwealth of Virginia's Aquatic Wildlife Conservation Center in Marion, VA. Quantitative PCR and eDNA metabarcoding were used to determine which planktonic microbes were present before and after the introduction of mussels into each experimental system. It was found that all five species preferentially consumed microeukaryotes over bacteria. Most microeukaryotic taxa, including Stramenopiles and Chlorophytes were quickly consumed by all five mussel species. We also found that they consumed fungi but not as quickly as the microalgae, and that one species of mussel, Ortmanniana pectorosa, consumed bacteria but only after preferred food sources were depleted. Our results provide evidence that siphon feeding Unionid mussels can select preferred microbes from mixed plankton, and mussel species exhibit dietary niche differentiation. [ABSTRACT FROM AUTHOR]

Understanding past coastal variability is valuable for contextualizing modern changes in coastal settings, yet existing Holocene paleoceanographic records for the North American Pacific Coast commonly originate from offshore marine sediments and may not represent the dynamic coastal environment. A potential archive of eastern Pacific Coast environmental variability is the intertidal mussel species Mytilus californianus. Archaeologists have collected copious stable isotopic (δ18O and δ13C) data from M. californianus shells to study human history at California's Channel Islands. When analyzed together, these isotopic data provide windows into 9000 years of Holocene isotopic variability and M. californianus life history. Here we synthesize over 6000 δ18O and δ13C data points from 13 published studies to investigate M. californianus shell isotopic variability across ontogenetic, geographic, seasonal, and millennial scales. Our analyses show that M. californianus may grow and record environmental information more irregularly than expected due to the competing influences of calcification, ontogeny, metabolism, and habitat. Stable isotope profiles with five or more subsamples per shell recorded environmental information ranging from seasonal to millennial scales, depending on the number of shells analyzed and the resolution of isotopic subsampling. Individual shell profiles contained seasonal cycles and an accurate inferred annual temperature range of ~ 5°C, although ontogenetic growth reduction obscured seasonal signals as organisms aged. Collectively, the mussel shell record reflected millennial-scale climate variability and an overall 0.52‰ depletion in δ18Oshell from 8800 BP to the present. The archive also revealed local-scale oceanographic variability in the form of a warmer coastal mainland δ18Oshell signal (-0.32‰) compared to a cooler offshore islands δ18Oshell signal (0.33‰). While M. californianus is a promising coastal archive, we emphasize the need for high-resolution subsampling from multiple individuals to disentangle impacts of calcification, metabolism, ontogeny, and habitat and more accurately infer environmental and biological patterns recorded by an intertidal species. [ABSTRACT FROM AUTHOR]

Successful aquatic biological invasions are often dependent on human vectors. The Chinese pond mussel Sinanodonta woodiana is a fast-growing, high-filtering, and highly fecund unionid bivalve that has expanded rapidly throughout Europe in the last several decades. Human-mediated vectors such as fish aquaculture and pet shop trade are believed to be primary drivers of the mussel's spread, but the specific dispersal pathways of S. woodiana remain unclear. We analyzed eleven microsatellites in 245 S. woodiana individuals from seven wild populations and three pet shops to assess genetic relatedness potential sources, and dispersal pathways of S. woodiana in Bavaria, Germany. Wild populations shared a single mitochondrial haplotype present in all European populations and shop-sourced individuals were genetically similar to wild populations. Only one wild population was structurally different than all other populations, which may be explained by its dispersal trajectory. Our results provide the first genetically informed insights into S. woodiana dispersal in the context of human activity. We underscore the value of genetic tools in invasive species management, which can uncover patterns of dispersal even on local scales. [ABSTRACT FROM AUTHOR]

Rare earth elements (REE) are essential components of many electronic devices that could end-up in solid waste disposal sites and inadvertently released in the environment. The purpose of this study was to examine the toxicity of two heavy REEs, erbium (Er) and lutetium (Lu), in freshwater mussels Dreissena polymorpha. Mussels were exposed to 14 days to increasing concentration (10, 50, 250, and 1250 µg/L) of either Er and Lu at 15 °C and analyzed for gene expression in catalase (CAT), superoxide dismutase (SOD), metallothionein (MT), cytochrome c oxidase (CO1), and cyclin D for cell cycle. In addition, lipid peroxidation (LPO), DNA damage (DNAd), and arachidonate cyclooxygenase were also determined. The data revealed that mussels accumulated Er and Lu similarly and both REEs induced changes in mitochondrial COI activity. Er increased cell division, MT, and LPO, while Lu increased DNAd and decreased cell division. Tissue levels of Er were related to changes in MT (r = 0.7), LPO (r = 0.42), CO1 (r = 0.69), and CycD (r = 0.31). Lu tissue levels were related to changes in CO1 (r = 0.73), CycD (r = − 0.61), CAT (r = 0.31), DNAd (r = 0.43), and SOD (r = 0.34). Although the lethal threshold was similar between Er and Lu, the threshold response for LPO revealed that Er produced toxicity at concentrations 25 times lower than Lu suggesting that Er was more harmful than Lu in mussels. In conclusions, the data supports that the toxicity pattern differed between Er and Lu although they are accumulated in the same fashion. [ABSTRACT FROM AUTHOR]

The research included 120 specimens of Pinna nobilis cultivated at a commercial park for oyster (Ostrea edulis) and black mussel (Mytilus galloprovincialis) cultivation. Research was carried out from 2012 to 2016, prior to the start of the mass extinction of fan mussel in the Mediterranean During the study period, the average sea temperature at a depth of 3 m was 14.87 ± 4.22 °C, ranging from 7.83 to 24.90 °C. The age of the specimens at the beginning of sexual maturity was approximately three years. The average length of the specimens throughout the study was 293.01 ± 16.58 mm. Gonad status was monitored monthly by sampling. The gender ratio in the study was 46 females (38.4%), 50 males (41.6%), and 24 undetermined individuals (20%). In our study, the results showed that males mature slightly earlier than females. The main spawning season occurred during the warmer part of the year when seawater exceeded 18 °C, starting in May and lasting until November. During the study, the GSI varied as expected and peaked in June (12.1), increasing from May to September. [ABSTRACT FROM AUTHOR]

The assessment of site suitability is a crucial step for informing future successful species reintroductions. It ensures that translocated species have the highest chance of survival in their new environment while minimising ecological risks. However, it can be challenging when risk factors are unknown, especially when working with sessile species that cannot easily relocate to more favourable conditions. Under these scenarios, rapid (1-2 week-long), small-scale (< 1 m²) experimental translocations can help reduce uncertainty and improve restoration outcomes. This study conducted small-scale experimental translocations of green-lipped mussels, Perna canaliculus, to 11 shallow coastal sites spread across Tık? apa Moana/the Hauraki Gulf, Aotearoa/New Zealand to investigate the relationship between predator abundance, environmental factors, and mussel loss to help refine existing site selection criteria. The total number of known mussel predators counted from timelapse images was used as a proxy for potential predator pressure. Translocated mussel survival ranged from 10 - 99% and was best predicted by current speed, wind direction, predator abundance, water clarity, and depth (adjusted R² = 0.505). Predator abundance was best explained by site location (p = 0.001) and had weak correlations among environmental parameters (Rho = 0.067). These results suggest that small, short-term (1-2 week) experimental translocations can help to refine site selection criteria and reduce uncertainty in the site-selection process for larger-scale shellfish reintroduction efforts with unknown and/or hard-tocontrol risk factors. [ABSTRACT FROM AUTHOR]

Gamete traits can vary widely among species, populations and individuals, influencing fertilisation dynamics and overall reproductive fitness. Sexual selection can play an important role in determining the evolution of gamete traits with local environmental conditions determining the strength and direction of sexual selection. Here, we test for signatures of post‐mating selection on gamete traits in relation to population density, and possible interactive effects of population density and sperm concentration on sperm motility and fertilisation rates among natural populations of mussels. Our study shows that males from high‐density populations produce smaller sperm compared with males from low‐density populations, but we detected no effect of population density on egg size. Our results also reveal that females from low‐density populations tended to exhibit lower fertilisation rates across a range of sperm concentrations, although this became less important as sperm concentration increased. Variances in fertilisation success were higher for females than males and the effect of gamete compatibility between males and females increases as sperm concentrations increase. These results suggest that local population density can influence gamete traits and fertilisation dynamics but also highlight the importance of phenotypic plasticity in governing sperm–egg interactions in a highly dynamic selective environment. [ABSTRACT FROM AUTHOR]

Predators affect their prey through consumptive and non-consumptive effects (NCEs). Regarding marine NCEs, predator chemical cues (e.g., exudates) can trigger various anti-predator responses in prey that can vary in magnitude according to the intensity of the perceived cues. Specimens of the mussel Perumytilus purpuratus were exposed to seawater that held different densities of the predatory snail Acanthina monodon as a proxy for predator cue intensity. The response of mussels was quantified in terms of valve gape size (VGS), clearance rate (CR), and oxygen consumption rate (OCR). The results showed that mussels reduced VGS, CR, and OCR as a function of the intensity of the predator exudates to which they were exposed. These results suggest that mussels are not only able to detect predators through their chemical exudates but can also detect the intensity of the predatory signal and thus respond physiologically (CR, OCR) and behaviorally (VGS) in accordance to the potential predation risk. These responses may have cascading effects at the community level, given that mussels are foundation species. [ABSTRACT FROM AUTHOR]

The overproduction and mismanagement of plastics has led to the accumulation of these materials in the environment, particularly in the marine ecosystem. Once in the environment, plastics break down and can acquire microscopic or even nanoscopic sizes. Given their sizes, microplastics (MPs) and nanoplastics (NPs) are hard to detect and remove from the aquatic environment, eventually interacting with marine organisms. This research mainly aimed to achieve the aggregation of micro- and nanoplastics (MNPs) to ease their removal from the marine environment. To this end, the size and stability of polystyrene (PS) MNPs were measured in synthetic seawater with the different components of the technology (ionic liquid and chitosan). The MPs were purchased in their plain form, while the NPs displayed amines on their surface (PS NP-NH2). The results showed that this technology promoted a significant aggregation of the PS NP-NH2, whereas, for the PS MPs, no conclusive results were found, indicating that the surface charge plays an essential role in the MNP aggregation process. Moreover, to investigate the toxicological potential of MNPs, a mussel species (M. galloprovincialis) was exposed to different concentrations of MPs and NPs, separately, with and without the technology. In this context, mussels were sampled after 7, 14, and 21 days of exposure, and the gills and digestive glands were collected for analysis of oxidative stress biomarkers and histological observations. In general, the results indicate that MNPs trigger the production of reactive oxygen species (ROS) in mussels and induce oxidative stress, making gills the most affected organ. Yet, when the technology was applied in moderate concentrations, NPs showed adverse effects in mussels. The histological analysis showed no evidence of MNPs in the gill's tissues. [ABSTRACT FROM AUTHOR]

Bisphenols and phthalates are wide classes of endocrine disrupting chemicals (EDCs) extensively used as additives in plastic products. In this study, a fast and reliable analytical method based on matrix solid-phase dispersion (MSPD) coupled with LC-MS/MS was developed and optimized for simultaneous determination of 8 bisphenols and 7 phthalates in raw mussel extract. The LC-MS/MS method was tested for linearity (R2), inter- and intra-day repeatability, limit of detection and quantification, both for matrix-free and matrix-matched solutions. The MSPD method was optimized in terms of ratio between sample and sorbent, and the type and quantity of the eluents in order to maximize the recoveries and to minimize matrix effects. The obtained recoveries (values between 75% and 113%), limits of detection (values between 0.048 and 0.36 µg kg−1), limits of quantification (values between 0.16 and 1.28 µg kg−1), repeatability (RSD% between 1.30% and 8.41%) and linearity (R2 > 0.998) were satisfactory and suitable for the determination of target micropollutants in food samples. In addition, the low solvent consumption and fast execution make this method ideal for routinely determinations of bisphenols and phthalates in mussels. [ABSTRACT FROM AUTHOR]

Hexachlorobenzene （HCHs）, dichlorodiphenyltrichloroethane（DDTs） and poly-chlorinated biphenyls （PCBs） were determined in water, soil and mussel samples using GC-MS/MS, in order to investigate the concentrations, composition and distribution characteristics of legacy persistent organic pollutants （POPs） in different medium in the mussel mariculture area of the Huaniao Island, Yangtze estuary. The results showed that legacy POPs were widely detected in the samples, and the concentrations of HCHs, DDTs and PCBs ranged from 10. 8 to 49. 1, 169 to 900 and 10. 4 to 34. 4 ng/g（lipid weight） in mussel, 0. 22 to 1. 76, 0. 07 to 0. 29 ng/L and 9. 45-51. 8 pg/L in water, and 0. 18 to 10. 4, 2. 62 to 69. 6 and 0. 40 to 0. 69 ng/g（dry weight） in soil, respectively. DDTs were the main pollution compounds in mussel. The composition of target compounds in water and soil samples from the mariculture area reflected their exposure to residual pollutant emissions, with a dominance of highly chlorinated PCBs and DDT degradation products in mussels, which was associated with bioaccumulation characteristics. There were many significant positive correlations among HCHs, DDTs and PCBs in soils, as well as in mussels, reflecting the possible existence of similar sources of contaminants. The relationship between mussel tissues and non-biological medium can be seen in the principal component analysis. Health risk assessment showed that population ingestion of local mussels posed little risk of exposure and carcinogenic potential. This study can provide a basis for understanding the fate of legacy POPs among the different medium in the mussel mariculture area and the risk of mussel consumption by the population. [ABSTRACT FROM AUTHOR]

This study surveyed freshwater mussels (family Unionidae) in 116 lakes and reservoirs east of the Missouri River in South Dakota, USA, during 2017. Using two-person–hour/site timed searches, evidence of a total of 1789 mussels, including 1053 live mussels, was obtained from 50 waters. Nine species, from two different orders, were found in lakes and reservoirs throughout five of the six major river drainages east of the Missouri River. The native species observed included Giant Floater Pyganodon grandis, Fatmucket Lampsilis siliquoidea, Threeridge Amblema plicata, White Heelsplitter Lasmigona complanata, Wabash Pigtoe Fusconaia flava, Deertoe Truncilla truncata, and Pink Heelsplitter Potamilus alatus. Giant Floater was the most widespread and abundant species observed, representing 63.3% of the live mussels sampled. Two non-native species, Zebra Mussel Dreissena polymorpha and Chinese Basket Clam Corbicula fluminea, were also documented from three water bodies in the lower Missouri River drainage. Overall, mussel abundance was negatively correlated with lake water conductivity and positively correlated with turbidity. No significant correlations were observed between species abundance and water temperature, pH, dissolved oxygen, or substrate particle size. [ABSTRACT FROM AUTHOR]

The ASTM International standard test method for freshwater mussels (E2455‐13) recommends 4‐week toxicity testing with juveniles to evaluate chronic effects on survival and growth. However, concerns remain that the method may not adequately address the sensitivity of mussels to longer term exposures (>4 weeks), particularly in relation to potential reproductive impairments. No standard method directly evaluates toxicant effects on mussel reproduction. The objectives of the present study were to (1) evaluate toxicity endpoints related to reproduction in fatmucket (Lampsilis siliquoidea) using two common reference toxicants, potassium chloride (KCl) and nickel (Ni); (2) evaluate the survival and growth of juvenile fatmucket in standard 4‐week and longer term (12‐week) KCl and Ni tests following a method refined from the standard method; and (3) compare the sensitivity of the reproductive endpoints with the endpoints obtained from the juvenile mussel tests. Reproductive toxicity tests were conducted by first exposing female fatmucket brooding mature larvae (glochidia) to five test concentrations of KCl and Ni for 6 weeks. Subsamples of the glochidia were then removed from the adults to determine three reproductive endpoints: (1) the viability of brooded glochidia; (2) the viability of free glochidia in a 24‐h exposure to the same toxicant concentrations as their mother; and (3) the success of glochidia parasitism on host fish. Mean viability of brooded glochidia was significantly reduced in the high KCl concentration (26 mg K/L) relative to the control, with a 20% effect concentration (EC20) of 14 mg K/L, but there were no significant differences between the control and any Ni treatment (EC20 > 95 µg Ni/L). The EC20s for viability of free glochidia after the additional 24‐h exposure and parasitism success were similar to the EC20s of brooded glochidia. The EC20s based on the most sensitive biomass endpoint in the 4‐week juvenile tests were 15 mg K/L and 91 µg Ni/L, similar to or greater than the EC20s from the reproductive KCl and Ni tests, respectively. When exposure duration in the juvenile tests was extended from 4 to 12 weeks, the EC20s decreased by more than 50% in the KCl test but by only 8% in the Ni test. Overall, these results indicate that a standard 4‐week test with juvenile mussels can prove effective for estimating effects in chronic exposures with different life stages although a longer term 12‐week exposure with juvenile mussels may reveal higher sensitivity of mussels to some toxicants, such as KCl. Environ Toxicol Chem 2024;43:1097–1111. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Site selection is one of the biggest challenges affecting coastal restoration success, and can be particularly difficult in the intertidal zone, where species are often living close to their physiological thermal limits. Climate change is causing atmospheric and marine heat waves, with the summer of 2023 having the highest ever recorded global average temperatures. This changing climate, along with other intertidal stressors, increases the difficulty for managers to choose restoration locations in the intertidal zone. In this study, green‐lipped mussels (Perna canaliculus) were transplanted into the intertidal zone in a series of 12 plots (9 m2) to examine the in situ influence of temperature on mussel survival over a 6‐month period. The plots were deployed at varying intertidal heights with differing periods of aerial exposure and temperature. Six months post‐deployment the plots had highly variable mussel survival with a range of 0–95%. Results showed that temperature, specifically hours exceeding 25°C, had a negative relationship with mussel survival, and reducing aerial exposure reduces the number of hours exposed to temperatures above 25°C in the summer months. This study demonstrates the utility of deploying temperature loggers by restoration practitioners prior to restoration trials to determine localized variances in temperature and exposure that may aid in site selection in the intertidal zone. In a warming world, our findings illustrate the importance of understanding the potentially critical fine‐scale interplay between temperature and exposure time in intertidal shellfish restoration. [ABSTRACT FROM AUTHOR]

Background: Rosacea is a prevalent chronic dermatological condition marked by facial inflammation and erythema, significantly compromising the quality of life for affected individuals. Current treatment methods for rosacea are not considered ideal because of the complex etiology of the disease. Mussel adhesive protein (MAP) is a glycoprotein derived from the foot gland of mussels. The protein exhibits anti‐inflammatory properties, relieves skin itching, and promotes wound healing. Aims: We aimed to explore the feasibility of using MAP administered via microneedle delivery for treating rosacea and the potential molecular mechanism involved. Materials and Methods: The therapeutic effect and mechanism of MAP microneedle delivery in an LL‐37‐induced rosacea‐like mouse model were observed using morphological and histological methods. Twenty‐seven patients with erythematotelangiectatic rosacea (ETR) underwent treatment once every 1 month, with three treatments constituting one treatment course. The therapeutic effect was evaluated by comparing the clinical images taken at baseline, after the first treatment course, and after the second treatment course. The red value, CEA, and GFSS score were also calculated. Results: In response to the microneedle delivery of MAP, innate immunity, inflammatory infiltration, and abnormal neurovascular regulation improved significantly in rosacea‐like mice. In the clinical experiments, the microneedle delivery of MAP significantly improved the symptoms of erythema, flushing, and telangiectasia in patients with ETR, and no obvious adverse reactions were observed. Conclusions: MAP delivered by microneedling is effective and safe for treating ETR. [ABSTRACT FROM AUTHOR]

This study presents the use of a low-temperature hydrothermal method for extracting calcium sources from green mussel shell (P. Viridis) wastes and converting them into synthetic nanosized hydroxyapatite (HA). In this study, raw mussel shells were washed, pulverised, and sieved to start producing a fine calcium carbonate-rich powder. XRD quantitative analysis confirmed that the powder contains 97.6 wt. % aragonite. This powder was then calcined for 5 h at 900 °C to remove water, salt, and mud, yielding a calcium-rich feedstock with major minerals of calcite (68.7 wt.%), portlandite (24.7 wt.%), and minor aragonite (6.5 wt.%). The calcined powders were dissolved in aqueous stock solutions of HNO3 and NH4OH before hydrothermally reacting with phosphoric acid [(NH4)2HPO4], yielding pure, nanoscale (16-18 nm) carbonated HA crystals, according to XRD, FT-IR, and SEM analyses. The use of a low-temperature hydrothermal method for a feedstock powder produced by the calcination of low-cost mussel shell wastes would be a valuable processing approach for the industry's development of large-scale hydroxyapatite nanoparticle production. [ABSTRACT FROM AUTHOR]

In the present research, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was optimized and validated for the determination of 14 selected PCB congeners in mussel (Mytilus galloprovincialis) and fish samples (Sparus aurata). The optimization included the selection of different QuEChERS procedures, extraction solvent, sample weight, and suitable sorbents for the clean-up step to achieve high sensitivity and minimal matrix interferences simultaneously. The identification and quantification of the selected PCBs were carried out using GC–MS. The method was validated providing in all cases excellent linearity (r2 above 0.99). Recoveries were estimated at three different fortification levels (10, 50, and 100 ng g−1) and ranged from 72.5 to 109.5% and 72.1 to 88.4% for mussel and fish samples, respectively. In addition, for both matrices, the LOQs ranged from 1 to 2.5 ng g−1. The matrix effect was in all cases < 29%, while the expanded uncertainty U%, which was estimated at all the fortification levels, was found below 53% in all cases. Eventually, the optimized and validated method was applied to mussel and fish samples acquired from aquacultures in NW Greece, revealing the absence of the selected congeners in all cases. [ABSTRACT FROM AUTHOR]

Microplastics, as plastic fragments less than 5 millimeters (mm), are a global environmental concern that can provide a primary risk related to food contamination. Shellfish are marine organisms that are commonly subjected to microplastic contamination. The objectives of this study were to investigate microplastic contamination in spotted babylon (Babylonia areolata) and green mussels (Perna viridis) from supermarkets, local markets, and wholesale shops in Lampang province, Thailand. The results showed that spotted babylon and green mussels from the wholesale shop had the highest number of contaminated microplastics, with 1.67 ± 2.89 and 0.67 ± 0.58 particles/g wet weight, respectively. The average number of microplastics in the spotted babylon and green mussels were 0.89 ± 0.69 and 0.44 ± 0.19 particles/g wet weight, respectively. However, the number of microplastics was not significantly different among supermarkets, local markets, and wholesale shops (p > 0.05), and there was no significant difference between spotted babylon and green mussels (p > 0.05). The average length of microplastic particles found in spotted babylon and green mussels was 0.13 ± 0.14 and 0.12 ± 0.07 mm, respectively. The predominant fragment shape of microplastics found in spotted babylon and green mussels were 100.00% and 66.67%, respectively. The dominant colors of the microplastics found in spotted babylon and green mussels were blue (50.00%) and black (66.67%), respectively. The major microplastics detected were polypropylene (PP) in spotted babylon; PP and polyethylene terephthalate in green mussels. These polymers are commonly used in protective packaging and containers. Therefore, the findings of this study recommended microplastic prevention policies, especially regarding fishing and aquaculture sources. These policies could include monitoring the concentrations of microplastics in both wild and farmed seafood, encouraging circular design for fishing, evaluating the hazards and effects of microplastics on consumers, marking and tracking fishing gear to discourage discarding and facilitating the recovery of missing gear, and requiring the reporting of lost fishing and aquaculture gear to public authorities. [ABSTRACT FROM AUTHOR]

Research on the microbiota associated with marine invertebrates is important for understanding host physiology and the relationship between the host and the environment. In this study, the microbiota of the green mussel Perna viridis was characterized at the tissue scale using 16S rRNA gene high-throughput sequencing and compared with the microbiota of the surrounding environment. Different mussel tissues were sampled, along with two environmental samples (the mussel's attachment substratum and seawater). The results showed that the phyla Proteobacteria, Bacteroidetes, and Spirochaetae were dominant in mussel tissues. The bacterial community composition at the family level varied among the tissues of P. viridis. Although the microbiota of P. viridis clearly differed from that of the surrounding seawater, the composition and diversity of the microbial community of the foot and outer shell surface were similar to those of the substratum, indicating their close relationship with the substratum. KEGG prediction analysis indicated that the bacteria harbored by P. viridis were enriched in the degradation of aromatic compounds, osmoregulation, and carbohydrate oxidation and fermentation, processes that may be important in P. viridis physiology. Our study provides new insights into the tissue-scale characteristics of mussel microbiomes and the intricate connection between mussels and their environment. [ABSTRACT FROM AUTHOR]

Mussel periostracum, a nonliving multifunctional gel that covers the rigid inorganic shells of mussels, provides protection against mechanical impacts, biofouling, and corrosion in harsh ocean environments. The inner part of the periostracum, which emerges from biological tissues, functions as a natural interface between tissue and inorganic materials. The periostracum shows significant potential for application in implantable devices that provide interfaces; however, this system remains unexplored. In this study, we revealed that the inner periostracum performs graded mechanical functions and efficiently dissipates energy to accommodate differences in stiffness and stress types on both sides. On the tissue end, the lightly pigmented periostracum exhibits extensibility and energy dissipation under repetitive tension. This process was facilitated by the slipping and reassembly of β-strands in the discovered major proteins, which we named periostracin proteins. On the shell end, the highly pigmented, mineralized, and porous segment of the periostracum provided stiffness and cushioned against compressive stresses exerted by the shell valves during closure. These findings offer a novel possibilities for the design of interfaces that bridge human tissue and devices. The interfaces linking biological tissues and man-made devices is challenging due to mechanical mismatch, biofouling, and water content. Soft materials such as hydrogels have emerged in diverse applications, however, their unresolved problem is the loss of functions in a short period. This report explores natural connective tissue, called periostracum, which is perfectly bridged between biological tissue and inorganic nonliving shell with high durability for long-lasting functions. Its hierarchically designed strategy provides a novel blueprint to design durable soft materials for the interfacing device into tissue. [ABSTRACT FROM AUTHOR]

Horse mussel beds are listed as a Priority Marine Feature (PMF) in Scotland for their influence in the creation of diverse benthic communities and provision of ecosystem services. In Scotland, horse mussel beds are also recognised for their importance in marine carbon sequestration. Unfortunately, there is a paucity of data on horse mussel bed carbon stocks and sediment thickness. There are also significant financial and logistical barriers with which to address these data gaps. This study investigates the robustness of Sub-Bottom Profiling (SBP) as a costeffective method to quantify horse mussel sediment thickness across a landscape. Integrating SBP and Drop-Down Video (DDV) data, this study also details an integrated approach to investigate the links between horse mussel habitat condition and sediment thickness. With the addition of abiotic data, this study uses Structural Equation Modelling (SEM) to elucidate key relationships between abiotic factors, biotic variables, and sediment thickness. There is a significant positive correlation of horse mussel habitat condition and sediment thickness. Average horse mussel total sediment thickness, across all measures of habitat condition, was 1.37m. These findings substantially increase previous estimates of horse mussel sediment thickness, and potential value to climate change mitigation through blue carbon frameworks. This study highlights the importance of both abiotic and biotic factors on marine carbon sediment quantification. [ABSTRACT FROM AUTHOR]

Underwater adhesives with injectable, organic solvent‐free, strong, fast adhesion, and hemostatic properties have become an urgent need in biomedical field. Herein, a novel polyurethane underwater adhesive (PUWA) inspired by mussels is developed utilizing the rapid post‐cure reaction of isocyanate esterification without organic solvents. The PUWA is created through the injectable two component curing process of component A (biocompatible polyurethane prepolymer) and component B (dopamine modified lysine derivatives: chain extender‐LDA and crosslinker‐L3DA). The two‐component adhesive cures quickly and firmly underwater, with an impressive bonding strength of 40 kPa on pork skin and excellent burst pressure of 394 mmHg. Moreover, the PUWA exhibits robust adhesion strength in hostile environments with acid, alkali and saline solutions. Combined with excellent biocompatibility and hemostatic performance, the PUWA demonstrates effectively sealing wounds and promoting healing. With the ability to bond diverse substrates rapidly and strongly, the PUWA holds significant potential for application in both biomedical and industrial fields. [ABSTRACT FROM AUTHOR]

Ocean warming caused by global climate change influences the function, diversity, and community dynamics of commensal microorganisms, including the hemolymph and the gut microbiota in mussels. However, the microbiota in hard-shelled mussel (Mytilus coruscus) larvae and the effect of temperature on the microbial community structure have yet to be studied. Herein, we investigated the core microbiota of M. coruscus larvae and the impact of acute (4 h) and gradual (4 days) exposure to a rise in seawater temperature from 21 to 25 °C. Eleven core genera were identified in M. coruscus larvae by 16S rDNA gene sequencing: Alteromonas, Brevundimonas, Delftia, Microbacterium, Neptuniibacter, Neptunomonas, Pseudoalteromonas, Rhodococcus, Stenotrophomonas, Tenacibaculum, and Thalassotalea. The microbiota of larvae in the short exposure treatment was similar to the control. However, the abundance of Delftia, Neptunomonas, Pseudoalteromonadaceae, Rhodococcus, and Stenotrophomonas decreased significantly in the longexposure larvae. In contrast, at the genus level, the abundance of Tenacibaculum increased significantly. Diversity and multivariate analyses confirmed that the microbiota patterns were linked to seawater warming over the long term. Microbiota diversity did not change significantly, regardless of whether the seawater temperature increased quickly or slowly; however, we observed a significant increase in the microbiota species abundance at higher temperatures. Among the altered bacterial genera, Delftia, Neptunomonas, and Rhodococcus function in the degradation of organic compounds; Pseudoalteromonas is closely associated with mussel attachment and metamorphosis, and Tenacibaculum is an opportunistic pathogen that can cause marine mollusk death. The results suggest that marine heat waves caused by climate change may reduce the ability of symbiotic bacteria to degrade environmental toxins, will affect mussel larvae metamorphosis, and increase the abundance of opportunistic pathogens, thereby increasing the risk of disease and death of mussel larvae. [ABSTRACT FROM AUTHOR]

Widespread persistent contaminants are a global environmental problem. In the Baltic Sea, wildlife contamination was first noticed in the 1960s, prompting the Swedish Environmental Protection Agency to establish a comprehensive Swedish National Monitoring Programme for Contaminants in Marine Biota (MCoM) in 1978 run by the Swedish Museum of Natural History. Eight species have been analysed, four fish species (Atlantic herring, Atlantic cod, European perch, viviparous eelpout), one bivalve species (blue mussel), and egg from three bird species (common guillemot, common tern, Eurasian oystercatcher). Here, we present a dataset containing MCoM data from its start until 2021. It includes 36 sets of time-series, each analysed for more than 100 contaminants. The longest time-series is for common guillemot and starts in 1968. We describe the structure of MCoM including historic changes to the number of stations, sample treatment, analytical methods, instruments, and laboratories. The MCoM data is available at the Bolin Centre repository and on GitHub through our R package mcomDb. The latter will be updated yearly with new MCoM records. [ABSTRACT FROM AUTHOR]

Mytilus edulis is a commercially and ecologically important species found along the east coast of the United States. Ecologically, M. edulis improves water quality through filtration feeding and provides habitat formation and coastal protection through reef formation. Like many marine calcifiers, ocean warming, and acidification are a growing threat to these organisms—impacting their morphology and function. Museum collections are useful in assessing long-term environmental impacts on organisms in a natural multi-stressor environment, where acclimation and adaptation can be considered. Using the American Museum of Natural History collections ranging from the early 1900s until now, we show that shell porosity changes through time. Shells collected today are significantly more porous than shells collected in the 1960s and, at some sites, than shells collected from the early 1900s. The disparity between porosity changes matches well with the warming that occurred over the last 130 years in the north Atlantic suggesting that warming is causing porosity changes. However, more work is required to discern local environmental impacts and to fully identify porosity drivers. Since, porosity is known to affect structural integrity, porosity increasing through time could have negative consequences for mussel reef structural integrity and hence habitat formation and storm defenses. [ABSTRACT FROM AUTHOR]

Simple Summary: Antibiotics are emerging contaminants found in several matrices of environmental, animal, and human origin. This high occurrence constitutes a major global threat, which is also responsible for the development of antimicrobial resistance. Therefore, it is vitally important to develop new, simple, and reliable methods by which to quantify them in several matrices. In this work, the mussel matrix was chosen as the sentinel organism; a new analytical method for the determination of two commonly used macrolides in mussels harvested along the Sardinian coasts was developed. None of the tested macrolides were found in the sampling sites at concentrations quantifiable by the developed method. These results can be useful for competent authorities evaluating the food safety of mussels (as concerns the studied antibiotics) and pollution derived from these drugs in the marine environment. Contaminants of emerging concern (CECs) are compounds found in several environmental compartments whose ubiquitous presence can cause toxicity for the entire ecosystem. Several personal care products, including antibiotics, have entered this group of compounds, constituting a major global threat. It is essential to develop simple and reliable methods by which to quantify these contaminants in several matrices. In this work, mussels were chosen as sentinel organisms to assess environmental pollution and the safety of bivalve mollusk consumption according to the "One Health perspective". A liquid chromatographic tandem mass spectrometry method (LC-MS/MS) was developed for the quantification of two macrolides, erythromycin (ERY) and azithromycin (AZI), in mussels. This new method was validated according to international guidelines, showing high selectivity, good recoveries (>60% for both of them), sensitivity, and precision. The method was successfully applied for ERY and AZI research in mussels farmed along the Sardinian coasts (Italy), demonstrating itself to be useful for routine analysis by competent authorities. The tested macrolides were not determined in the analyzed sites at concentrations above the limits of detection (LODs). These results demonstrate the food safety of mussels (as concerns the studied antibiotics) and a negligible amount of pollution derived from these drugs in the studied area. [ABSTRACT FROM AUTHOR]

The New Zealand Greenshell™ mussel (Perna canaliculus) is endemic to New Zealand and contributes to the success of the country's aquaculture industry. However, summer mortality and potential disease outbreak events are having an increasing effect on the growth of this industry. The cause of these mortalities remains unknown, and histopathological studies of the pathogen and parasites in mussels are still incomplete. In the present study, a histological approach was used to identify pathogens and parasites, as well as immunological tissue responses in unhealthy- and healthy-looking P. canaliculus during a summer mortality event in 2018. A highly significant association between health conditions and the presence of Perkinsus olseni in mussels was observed. A higher prevalence of P. olseni, Apicomplexan-X (APX), and bacterial (rods and cocci) infections were noted in the unhealthy-looking mussels than in the healthy-looking mussels. In an assessment of stains, hematoxylin and eosin (H&E) staining appeared to be the best method for general pathological and anatomical characterization, while Giemsa provided the clearest visual definition of bacteria. In this aspect, it was comparable to Ziehl–Neelsen (ZN) in apparent sensitivity. Although Gram and ZN staining revealed bacterial cells marginally better than with H&E, their differential staining could not be assessed as no Gram-positive or acid-fast bacteria were seen, and no mussel-positive controls were available for comparison. This study also provides an illustrated guide to some significant mussel health indicators. [ABSTRACT FROM AUTHOR]

Ascidian biofouling generates significant challenges to bivalve aquaculture. Their rapid spread across almost every available surface leads to increased maintenance costs and reduced yields in shellfish farming. In addition, ascidians may introduce pathogens or toxins, further compromising the health and marketability of bivalve stocks and thereby necessitating strict management strategies to manage these impacts. The aim of this study was the evaluation of different management practices for eliminating ascidian fouling and the identification of the best method for Mytilus galloprovincialis (Lamarck, 1819) aquaculture farms. The effects of different anti-fouling treatments as well as their interactive outcomes were examined by conducting two experiments. Various experimental procedures were applied, including the temporally differential washing of mussels, air exposure and immersion in 50 ppt and 70 ppt salinity solutions, as well as the combination of these applications. All treatments reduced the number of ascidian colonies on mussel socks but at varying proportions. Immersing mussel socks in a 70 ppt salinity solution followed by air exposure for 1 day was the most efficient method and led to a 93% eradication. [ABSTRACT FROM AUTHOR]

Biodiesel represents a promising solution for sustainable energy needs, offering an eco-friendly alternative to conventional fossil fuels. In this research, we investigate the use of a catalyst derived from mussel shells to facilitate biodiesel production from Jatropha curcas oil. Our findings from X-ray Fluorescence (XRF) analysis emphasize the importance of carefully selecting calcination temperatures for mussel shell-based catalysts, with 1100 °C identified as optimal for maximizing CaO content. We identify a reaction time of 6 h as potentially optimal, with a reaction temperature of approximately 110 °C yielding the desired methyl ester composition. Notably, a methanol-to-oil ratio of 18:1 is the most favorable condition, and the optimal methyl ester composition is achieved at a calcined catalyst temperature of 900 °C. We also assess the stability of the catalyst, demonstrating its potential for reuse up to five times. Additionally, a thorough analysis of J. curcas Methyl Ester (JCME) biodiesel properties confirmed compliance with industry standards, with variations attributed to the unique characteristics of JCME. Comparing homogeneous (NaOH) and heterogeneous (CaO) catalysts highlights the potential of environmentally sourced heterogeneous catalysts to replace their homogeneous counterparts while maintaining efficiency. Our study presents a novel approach to sustainable biodiesel production, outlining optimal conditions and catalyst stability and highlighting additional benefits compared with NaOH catalysts. Therefore, utilizing mussel shell waste for catalyst synthesis can efficiently eliminate waste and produce cost-effective catalysts. [ABSTRACT FROM AUTHOR]

Aims This study investigated phenotypic and genotypic antimicrobial resistance profiles of Vibrio strains identified from Mytilus galloprovincialis farmed for human consumption in the Adriatic Sea Central Italy. Methods and results A total of 475 mussels (M. galloprovincialis) were involved in the present study, and culture-dependent microbiological methods permitted to identify a total of 50 Vibrio strains that were tested for antibiotic susceptibility followed by the genetic determinant detections. Antibiograms showed resistance against ampicillin (36.0%), amoxicillin-clavulanic acid (30.0%), gentamycin (14.0%), and imipenem (18.0%). Biomolecular assays amplified a total of 264 antibiotic resistance genes harbored by both susceptible and resistant Vibrio species. Among resistance genes, aac C2 (62.0%) and aad A (58.0%) for aminoglycosides, bla TEM (54.0%) for beta-lactams, qnr S (24.0%) for quinolones, tet D (66.0%) for tetracyclines, and van B (60.0%) for glycopeptides were mainly amplified by PCR assays. Conclusions Vibrio genus is involved in the antibiotic resistance phenomenon diffusion in the aquatic environments, as demonstrated by the harboring of many genetic determinants representing a kind of genetic " dark world ". [ABSTRACT FROM AUTHOR]

The size at first maturity of the bivalve Mytilus platensis d'Orbigny, 1842 was estimated in the intertidal population of Villa Gesell (37°15′S; 56°57′W), Buenos Aires, Argentina. We hypothesize a variation in population maturity associated with shell length (SL) and differences between females and males. Individuals were analyzed histologically, sexed (females and males), and classified as mature and immature. We carried out a kernel density estimation to allow us to visualize the distribution of the classifications based on the SL and used a generalized linear model to study the size at first sexual maturity for the population and between sexes. Our results showed immature specimens with reduced development in acini and expanded connective tissue. Mature males and females showed the acini expanded and filled with vitellogenic oocytes and spermatozoa, respectively. The size at first sexual maturity at which 50% of the population was mature (SL50) was 11.80 mm SL for all population, while SL50 was 11.42 mm in females and 10.83 mm in males. We determined significant interaction between SL and sex (P < 0.05). We conclude that the knowledge of the reproductive aspects in intertidal populations is essential for the development of a potential fishing resource. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis (OA) can cause disability and reduce quality of life (QoL). Objectives: This study aimed to determine whether GreenShell mussel (GSM) powder (PERNAULTRA) consumption was more effective than placebo at improving physical performance and subjective measures of symptoms and function in adults with early signs of knee OA. Methods: The Researching Osteoarthritis and GSM study was a 6-mo randomized, double-blind, placebo-controlled trial in adults aged 55-80 y, screened for signs of OA (n = 120, 65.9 ± 6.43 y, 63% female). Participants consumed either 3 g of powdered whole GSM or placebo (pea protein) daily. Baseline and end data collection included 30-s chair stand, stair test, 40-m fast-paced walk test, Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire categorized into 5 subscales [pain (P), symptoms except pain (S), function in activities of daily living (ADL), function in sports/recreation (SP), and QoL], a measure of Intermittent and Constant Osteoarthritis Pain, and visual analog scale of pain and symptoms. Results: Visual analog scale symptoms showed a significantly greater reduction in percentage change for GSM than that for placebo [-28.1 (-59.2, 43.2) compared with 0.00 (-28.6, 100); P = 0.03]. Further, a trend for improvement in percentage change for GSM compared with placebo was seen in 40m fast-paced walk [2.51 (-3.55, 8.12) compared with 0.20 (-6.58, 4.92); P = 0.09], KOOS-SP [11.4 (-4.48, 27.0) compared with 0.00 (-11.1, 17.7); P = 0.09], and Intermittent and Constant Osteoarthritis Pain intermittent pain scale [-27.7 (-77.3, 0.00) compared with -14.6 (-50.0, 36.4); P = 0.08]. In those with body mass index (BMI; in kg/m²) <25, GSM consumption significantly improved KOOS-S compared with placebo [6.35 (3.49, 12.7) compared with 0.00 (-4.65, 4.49); P = 0.03] and showed a trend for improvement in KOOS-ADL [3.29 (1.01, 8.79) compared with 1.01 (-5.75, 4.30); P = 0.07]. Those with BMI of >25, consuming GSM showed a trend for improvement in KOOS-SP [13.6 (-4.76, 33.3) compared with 0.00 (-12.5, 20.0); P = 0.07]. Conclusions: This research suggests consumption of GSM has potential to alleviate symptoms and improve functionality in OA. [ABSTRACT FROM AUTHOR]

Xenograft bone granules are bone graft materials that are widely used to reconstruct bone tissue in clinical practice, and their clinical success requires aggregation with a biocompatible binder. While the catechol mussel bioadhesive has been used as a key universal biomedical glue moiety, the thiols in mussel adhesive proteins have recently been shown to play key roles in mussel wet adhesion. Here, pentaerythritol tris(3-mercaptopropionate)-di-catechol (PETMP-di-catechol), a catechol- and thiol-containing binder molecule that mimics mussel adhesive proteins, was used to aggregate xenograft bone granules and reconstruct bone tissue. The PETMP-di-catechol-aggregated xenograft bone granules were most resistive to compression stress when both the catechol and thiol moieties in PETMP-di-catechol were chemically oxidized with sodium periodate. The xenograft bone granules aggregated with the oxidized PETMP-di-catechol exhibited enhanced osteogenic cellular behavior in vitro and in vivo in a rat calvarial defect model, compared to the control group treated with catechol-conjugated chitosan, a catechol-containing polymer binder devoid of thiol moieties. Hence, the thiol-containing catechol-functionalized binder exhibits improved bone tissue reconstruction properties by mimicking mussel wet adhesion. In addition, our study suggests that PETMP-di-catechol is a potential biocompatible bone binder for use in clinical settings. [ABSTRACT FROM AUTHOR]

Blastocystis sp. is the most common single-celled eukaryote colonizing the human gastrointestinal tract worldwide. Because of the proven zoonotic potential of this protozoan, sustained research is therefore focused on identifying various reservoirs of transmission to humans, and in particular animal sources. Numerous groups of animals are considered to be such reservoirs due to their handling or consumption. However, some of them, including mollusks, remain underexplored. Therefore, a molecular epidemiological survey conducted in wild mussels was carried out in Northern France (Hauts-de-France region) to evaluate the frequency and subtypes (STs) distribution of Blastocystis sp. in these bivalve mollusks. For this purpose, 100 mussels (Mytilus edulis) were randomly collected in two sampling sites (Wimereux and Dannes) located in the vicinity of Boulogne-sur-Mer. The gills and gastrointestinal tract of each mussel were screened for the presence of Blastocystis sp. by real-time polymerase chain reaction (qPCR) assay followed by direct sequencing of positive PCR products and subtyping through phylogenetic analysis. In parallel, sequences of potential representative Blastocystis sp. isolates that were previously obtained from temporal surveys of seawater samples at marine stations offshore of Wimereux were integrated in the present analysis. By taking into account the qPCR results from all mussels, the overall prevalence of the parasite was shown to reach 62.0%. In total, more than 55% of the positive samples presented mixed infections. In the remaining mussel samples with a single sequence, various STs including ST3, ST7, ST14, ST23, ST26 and ST44 were reported with varying frequencies. Such distribution of STs coupled with the absence of a predominant ST specific to these bivalves strongly suggested that mussels might not be natural hosts of Blastocystis sp. and might rather be carriers of parasite isolates from both human and animal (bovid and birds) waste. These data from mussels together with the molecular identification of isolates from marine stations were subsequently discussed along with the local geographical context in order to clarify the circulation of this protozoan in this area. The identification of human and animal STs of Blastocystis sp. in mussels emphasized the active circulation of this protozoan in mollusks and suggested a significant environmental contamination of fecal origin. This study has provided new insights into the host/carrier range and transmission of Blastocystis sp. and emphasized its potential as an effective sentinel species for water quality and environmental contamination. [ABSTRACT FROM AUTHOR]

The invasive alien false mussels Mytilopsis leucophaeata cochleata and Dreissena polymorpha (Dreissenidae) have established populations in the North Sea canal in the Netherlands that connects the harbours of Amsterdam with the North Sea. The favourable and unfavourable salinity ranges of both species were earlier studied in long-term outdoor mesocosm experiments. Their occurrence in salinity gradients in estuaries or canals connecting seaways to freshwater harbours provides information on their salinity tolerance under field conditions. By the combination of laboratory experiments and field data using the same source population a high predictability can be expected for establishment of the gradients facilitated by constructions. The reliability of experimentally derived salinity-tolerance limits for both dreissenid species was tested using data on their distribution in a salinity gradient of the littoral zone along the North Sea canal. The mussels used for the survival experiments in mesocosms were also collected from this canal. Favourable salinity ranges for adult survival in the mesocosms were 0.2 – 17.5 for M. leucophaeata cochleata and 0.2 – 6.0 for D. polymorpha. Unfavourable salinities were outside these ranges and led to high and fast mortality of these species. Mytilopsis leucophaeata cochleata was present over nearly the whole length of the North Sea canal with the highest densities close to the sea sluices where also the highest salinities and water temperatures were measured. Their densities in the canal decreased gradually at larger distances from the sea. Dreissena polymorpha co-exists with M. leucophaeata cochleata at the east end of the canal with low salinity due to the influence of freshwater of the river Rhine. The occurrence of D. polymorpha was restricted to a salinity below 4 and M. leucophaeata cochleata only occurred at a salinity above 1.5 (maximum value measured in the canal 9.2). Shorter salinity gradients with lower salinity ranges provided additional information on the co-existence of both species. Co-existence was observed at a salinity range of 1.5–3.3 (own data), 1.0–3.5 (Van Couwelaar and Van Dijk 1989), both in the North Sea canal, and 0.2–2.8, in the Canal through Voorne (Janssen and Janssen-Kruit 1967). These data correspond with studies of both species by Walton (1996) in the Hudson River (salinity range 0–3). Found salinity ranges in the North Sea canal for both species match with the tolerance results obtained by mesocosm experiments. A new invading dreissenid mussel Dreissena rostriformis bugensis and a mytilid Ischadium recurvum occur in the North Sea canal since 2006 and 2012, respectively. Competition between recent and earlier invaders is likely when salinity tolerances are similar. It has already been observed that D. rostriformis bugensis outcompetes D. polymorpha under freshwater conditions (Bij de Vaate et al. 2014; Matthews et al. 2014). Ischadium recurvum has the potential to colonize large parts of the canal and to be a strong competitor of M. leucophaeata cochleata (Goud et al. 2019). Since January 2022, the new ‘Zeesluis IJmuiden’ with the biggest locks in the world is in use, affecting the probability of population establishment of new introduced and invasive alien mussel species. [ABSTRACT FROM AUTHOR]

Foundation species are spatially dominant species that increase habitat complexity and provide substrate and shelter for many smaller species. Through a mensurative field experiment, we tested the hypothesis that functional aspects of the associated communities are related to structural and functional properties of the foundation species. Specifically, we contrasted invertebrate communities living in mussel (Mytilus) and seaweed (Chondrus) stands from the same rocky intertidal environments in Atlantic Canada. Both stands reach similar heights above the substrate, but they differ structurally (rigid mussel shells vs. flexible seaweed fronds) and functionally (mussels generate biowaste while seaweeds offer food for herbivores). Our data supported the hypothesis in various ways. Detritivory (mostly by oligochaetes) was more prevalent in mussel stands, while herbivory was more prevalent in seaweed stands. Predators were mostly mites and, consequently, they were more prevalent in mussel stands, as mites eat oligochaetes. Functional traits related to body and mobility types were also related to properties of the foundation species. Overall, we conclude that structural and functional properties of foundation species can predict functional aspects of the associated communities. This concept may help to develop effective restoration strategies after the loss of foundation species due to anthropogenic factors. [ABSTRACT FROM AUTHOR]

Microplastics are plastic waste degraded by sunlight into small particles < 5 mm in size. Batik mussels (Paphia undulata) have filter feeder properties, few detoxification enzymes, and are sedentary animals; therefore, they are very likely to be contaminated with microplastics. This study aimed to determine the abundance of microplastics and the level of community consumption of batik mussels (Paphia undulata) in the waters of Banyuurip and Ujungpangkah, Gresik Regency, East Java. The research stage consisted of primary and secondary data collection. Mussle samples were collected using purposive sampling at two locations: Banyuurip and Ujungpangkah. For complementary data, direct interviews were conducted with communities in the field. Data analysis was carried out descriptively based on the data obtained. The results of this study showed that there were 3 forms of microplastics found in this research, there are fiber, fragments, and filaments the dominant form is fiber with a total of 100 particles/head. Fiber is caused by the activities of fishermen and is a form that easily accumulates during the digestion of biota. Blue was the dominant color found in all locations. The microplastic particles ranged in size from 0.083 to 4.619 mm. The highest abundance of microplastics was found at location 2 with 0.78 particles/head. The results of interviews with 30 respondents indicated that the local community consumed batik mussels at a weekly frequency of 15 people, with an average consumption of < 50 g/day for 18 people and > 50 g/day for 12 people. [ABSTRACT FROM AUTHOR]

Endocrine-disrupting chemicals (EDCs) represent a global threat to human health and the environment. In vertebrates, lipophilic EDCs primarily act by mimicking endogenous hormones, thus interfering with the transcriptional activity of nuclear receptors (NRs). The demonstration of the direct translation of these mechanisms into perturbation of NR-mediated physiological functions in invertebrates, however, has rarely proven successful, as the modes of action of EDCs in vertebrates and invertebrates seem to be distinct. In the present work, we investigated the members of the NR superfamily in a bivalve mollusk, the Mediterranean mussel Mytilus galloprovincialis. In addition to annotating the M. galloprovincialis NR complement, we assessed the potential developmental functions and susceptibility to EDC challenge during early development by gene expression analyses. Our results indicate that a majority of mussel NRs are dynamically expressed during early development, including receptors characterized by a potential susceptibility to EDCs. This study thus indicates that NRs are major regulators of early mussel development and that NR-mediated endocrine disruption in the mussel could be occurring at a larger scale and at earlier stages of the life cycle than previously anticipated. Altogether, these findings will have significant repercussions for our understanding of the stability of natural mussel populations. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'. [ABSTRACT FROM AUTHOR]

Simple Summary: Biological invasion, particularly by the invasive mussel Mytella strigata (Hanley, 1843), has led to a significant decline in the population of native Perna viridis (Linnaeus, 1758) in western Pacific regions. This study compared the intestinal microbiota, metabolome, and key digestive enzymes of these two competing mussels to elucidate their differences from intestinal microbiota and metabolic points. The analysis revealed differences in the abundance of Bacteroidota related to carbohydrate degradation, as well as enriched metabolites and higher carbohydrase activities in M. strigata compared to P. viridis. These findings suggested that these differences might contribute to the adaptation of M. strigata to its new environment, providing valuable insights into the competition between these species for food resources. Biological invasion is a primary direct driver of biodiversity loss. Recently, owing to exploitation competition with an invasive mussel, Mytella strigata (Hanley, 1843), there has been a drastic decrease in the population of native Perna viridis (Linnaeus, 1758) in several western Pacific regions. In the present study, intestinal microbiota, metabolome, and key digestive enzyme activities were compared between the two competing mussels, M. strigata and P. viridis, to elucidate the differences in intestinal microbiota and metabolic points. We observed that Proteobacteria, Firmicutes, and Bacteroidota were the three predominant bacterial phyla in the two species. The relative abundance of Bacteroidota related to carbohydrate-degrading ability was significantly higher in M. strigata than in P. viridis. Compared to P. viridis, different metabolites including maltose and trehalose were enriched in M. strigata. Lastly, higher carbohydrases activities of alpha-amylase, cellulase, and xylanase were observed in M. strigata than in P. viridis. These differences might play an important role in the adaptation process of M. strigata to the new environment. This study provides important basic knowledge for investigating the competition between M. strigata and P. viridis in terms of food resources utilization. [ABSTRACT FROM AUTHOR]

High performance bio-based materials are an important part of future sustainable technology, and engineered proteins provide excellent possibilities as functional polymers. Adhesives are widely needed for composite materials and biomimetic structures. In biological adhesives, two features have emerged as especially interesting—the role of coacervation and the presence of 3,4-dihydroxyphenylalanine (DOPA). To study these, protein engineering is used to construct a hybrid silk-mussel foot protein (mfp) adhesive. Tyr residues in the purified mfp are oxidized to DOPA and an encoded Spy Catcher-Tag system allowed easy click-chemistry to couple silk and mfp and to study the parts separately. The combined silk-mfp protein have a strong tendency to coacervate. DOPA affected the properties of coacervates and increased adhesion by several ways of measuring. In lap shear testing, the combined mfp-silk protein is superior to any of the components studied separately. Coacervation is suggested to contribute to the adhesion of silk-mfp, and shows several features suggested to lead to the strength and toughness of natural adhesives. In the lap shear system, coacervation have a stronger overall effect on adhesion than the presence of DOPA. The results show that protein design provides a route toward high performance biosynthetic polymers and future sustainable materials. [ABSTRACT FROM AUTHOR]

Due to the prevalence of plastic pollution in coastal ecosystems, aquatic organisms are at high risk for accumulating microplastics (MPs). Filter-feeding bivalves, such as mussels and oysters, may be exposed to, and subsequently accumulate, MPs due to the high volume of water they pass through their bodies. This study assessed the levels of MPs within Atlantic ribbed mussels (Geukensia demissa), a common filter feeder found along the United States Atlantic Coast, from 12 sites within Rehoboth Bay, Indian River Bay, and Little Assawoman Bay, collectively known as the Delaware Inland Bays. Composited mussels from each site were digested using potassium hydroxide and filtered. Microplastics were physically identified, sorted based on color, and counted using a digital microscope. Microplastics, almost entirely dominated by synthetic microfibers, were found in all mussels well above laboratory blanks. Across all sites, 40% of microfibers were black, and 27% of fibers were clear. The composite concentrations of MPs ranged from 0.25 to 2.06 particles/g wet tissue, with a mean of 0.08 ± 0.06. In general, higher concentrations were found in mussels collected at sites that were adjacent to more urbanized land use versus those from rural sites. At two sites, individual mussels, in addition to composites, were analyzed and had MP concentrations ranging from 11 to 69 particles/mussel. This study represents the first evaluation of MPs in this ecologically important coastal species and suggests its viability as a biomonitoring species for microplastic pollution. [ABSTRACT FROM AUTHOR]

Intertidal mussels (Mytilus spp.) and their benthic invertebrate predators were monitored annually for 25 years at 10 sites within Lough Hyne Marine Reserve in southwest Ireland. Mussel abundance was relatively low in the early 1990s but increased substantially after the cold winter of 1995/1996. High mussel abundance was maintained until 2014 after which there was an abrupt decline leading to low levels in 2015–2019, when populations were dominated by older size-classes. Recruitment on benthic rock surfaces in 2018 and 2019 was low in contrast to that on an isolated mooring rope in deep water, suggesting mortality of recruits (e.g. from predation or benthic hypoxia). The generalist predatory starfish, Marthasterias glacialis , increased substantially during the study, with population peaks in 2005 and 2009 that mirrored the peaks of mussel populations. Predatory dogwhelks were not abundant at the monitoring sites and were never seen associated with mussels. Predators or other physical factors may have reduced recruitment, but the decline of the mussel population probably reflected increasing age and removal by wave action combined with consistently sparse recruitment. [ABSTRACT FROM AUTHOR]

Information on crayfish–habitat relationships in agricultural headwater streams in the midwestern United States is limited and needed for the development of conservation strategies for crayfishes in these streams. In this research we asked: which physical, chemical, and biological variables are the best predictors of crayfish assemblage structure in agricultural headwater streams? We sampled crayfishes, fishes, and mussels and obtained watershed, climatic, riparian habitat, instream habitat, and water chemistry data from 17 agricultural headwater stream sites in Indiana, Michigan, and Ohio, USA, in 2014 and 2015. Mixed-effects model analyses, Akaike Information Criterion corrected for small sample size tests, average model coefficients, and variable importance values indicated that mean water velocity, % darters, predator fish length, watershed size, total precipitation, riparian width, and riparian woody vegetation density were the best predictors of crayfish assemblage structure. Our results suggest that conservation and restoration strategies that improve instream habitat, biotic, and riparian habitat variables will benefit native crayfishes in agricultural headwater streams in the midwestern United States. [ABSTRACT FROM AUTHOR]

Simple Summary: Perumytilus purpuratus is a mussel species that is broadly distributed along the latitudinal gradient from the Southern Pacific to the Atlantic Ocean. Along its distribution, P. purpuratus has been historically considered as one species. However, in the last decade, evidence has supported the hypothesis of two geographically divergent lineages. Within this context, we explore the evolutionary history of this inter-oceanic mussel, linking both sperm acrosome variability and molecular analyses of males at the geographic macroscale. In general, our results were in agreement with the genetic divergence that was previously reported, and showing two north and south lineage. Furthermore, our comprehensive sampling effort enabled us to precisely determine both the latitudinal positions of morpho-genetic break, which was identified at 37° S on the Pacific coast, and a probable hybridization zone at 38° S. In addition, we found new southern sperm variants, longer than previously reported. Overall, our results support the hypothesis of historical events and postglacial recolonization as causal phenomena for the observed divergences. Finally, we consider that, despite uncertainties in the taxonomy of P. purpuratus, the morpho-genetic divergence between the north and south P. purpuratus lineages indicates that they do not constitute the same Evolutionary Significant Unit and, therefore, they should be considered as separate entities. In recent years, advances in analyses of the sperm morphology and genetics of Perumytilus purpuratus have allowed to two evolutionary scenarios for this mussel to be suggested: (1) the scenario of cryptic species and (2) the scenario of incipient or in progress speciation. For a better understanding of the evolutionary history of P. purpuratus, we performed extensive sampling along a latitudinal gradient of ca. 7180 km of coastline—from the Southern Pacific Ocean to the Atlantic Ocean—and we delved deeper into the sperm morphology of P. purpuratus, exploring its association with the phylogeny and population genetics to determine whether the variability in sperm traits between the northern and southern regions was a signal of cryptic or incipient species. Overall, our results showed that sperm sizes were strongly correlated with the genetic structure in males of P. purpuratus. We identified at 37° S on the Pacific coast a coincident break of both sperm size and genetic disruption that can be explained by historical events and postglacial recolonization as causal phenomena for the observed divergences. Furthermore, evidence of genetic admixture between lineages was found at 38° S, suggesting the presence of an introgressive hybridization zone and incomplete reproductive isolation in an in fraganti or incipient speciation process. [ABSTRACT FROM AUTHOR]

Freshwater mussel populations are in sharp decline and are considered to be one of the most imperilled groups globally. Consequently, the number of captive breeding programmes has increased rapidly in recent years, coupled with subsequent reintroductions/population reinforcements to reverse these declines. The outcomes of mussel conservation translocations are seldom reported in the primary literature, hindering opportunities for learning and for population recovery at pace. Here, we describe the methods employed to carry out a successful conservation translocation of the freshwater pearl mussel (Margaritifera margaritifera) in a declining population in northwest England. Following a small-scale pilot release in 2017, four release sites were identified for a population reinforcement of over 1300 tagged mussels in 2021. Monitoring during 2022 showed high levels of retention of juveniles at three out of the four release sites, despite the occurrence of a significant flood event during October 2021. Subsequent releases of 1100 juveniles were carried out across the three successful sites in 2023. Ongoing and regular monitoring is essential in order to provide data on the longer-term fate of propagated juveniles in the wild. This will allow for adaptive management of release activities in this river. These data will be useful to design conservation translocation strategies for other imperilled pearl mussel populations in the UK and throughout Europe. [ABSTRACT FROM AUTHOR]

The effects of the climate crisis are affecting ecosystems at different scales and magnitudes. This paper focuses on a massive Mediterranean mussel die-off observed along the middle Italian Adriatic coast in the summer of 2022. We considered the possible environmental causes of this phenomenon and carried out a climatic analysis of the last decade. We performed field surveys in different locations along a 16 km coastal stretch from Martinsicuro (TE) in the south, to Grottammare (AP) in the north. The study area includes two marine Sites of Community Importance under the European Natura 2000 network. The die-off of the mussels was observed in practically all the natural mussel beds colonizing the study area. As sessile filter-feeding organisms inhabiting the intertidal zone, mussels are highly exposed to variations in environmental conditions such as temperature and nutrient load. We discuss the possible causes of this die-off, proposing that high temperature and the scarce availability of food acted simultaneously as stress factors, generating local unsustainable living conditions for this species. [ABSTRACT FROM AUTHOR]

The loose‐equilibrium concept (LEC) predicts that ecological assemblages change transiently but return towards an earlier or average structure. The LEC framework can help determine whether assemblages vary within expected ranges or are permanently altered following environmental change.Long‐lived, slow‐growing animals typically respond slowly to environmental change, and their assemblage dynamics may respond over decades, which transcends most ecological studies. Unionid mussels are valuable for studying dynamics of long‐lived animals because they can live >50 years and occur in dense, species‐rich assemblages (mussel beds). Mussel beds can persist for decades, but disturbance can affect species differently, resulting in variable trajectories according to differences in species composition within and among rivers.We used long‐term data sets (10–40 years) from seven rivers in the eastern United States to evaluate the magnitude, pace and directionality of mussel assemblage change within the context of the LEC.Site trajectories varied within and among streams and showed patterns consistent with either the LEC or directional change. In streams that conformed to the LEC, rank abundance of dominant species remained stable over time, but directional change in other streams was driven by changes in the rank abundance and composition of dominant species.Characteristics of mussel assemblage change varied widely, ranging from those conforming to the LEC to those showing strong directional change. Conservation approaches that attempt to maintain or create a desired assemblage condition should acknowledge this wide range of possible assemblage trajectories and that the environmental factors that influence those changes remain poorly understood. [ABSTRACT FROM AUTHOR]

Deep-sea mining activities can potentially release metals, which pose a toxicological threat to deep-sea ecosystems. Nevertheless, due to the remoteness and inaccessibility of the deep-sea biosphere, there is insufficient knowledge about the impact of metal exposure on its inhabitants. In this study, deep-sea mussel Gigantidas platifrons, a commonly used deep-sea toxicology model organism, was exposed to manganese (100, 1 000 µg/L) or iron (500, 5 000 µg/L) for 7 d, respectively. Manganese and iron were chosen for their high levels of occurrence within deep-sea deposits. Metal accumulation and a battery of biochemical biomarkers that related to antioxidative stress in superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA); immune function in alkaline phosphatase (AKP), acid phosphatase (ACP); and energy metabolism in pyruvate kinase (PK) and hexokinase (HK) were assessed in mussel gills. Results showed that deep-sea mussel G. platifrons exhibited high capacity to accumulate Mn/Fe. In addition, most tested biochemical parameters were altered by metal exposure, demonstrating that metals could induce oxidative stress, suppress the immune system, and affect energy metabolism of deep-sea mussels. The integrated biomarker response (IBR) approach indicated that the exposure to Mn/Fe had a negative impact on deep-sea mussels, and Mn demonstrated a more harmful impact on deep-sea mussels than Fe. Additionally, SOD and CAT biomarkers had the greatest impact on IBR values in Mn treatments, while ACP and HK were most influential for the low- and high-dose Fe groups, respectively. This study represents the first application of the IBR approach to evaluate the toxicity of metals on deep-sea fauna and serves as a crucial framework for risk assessment of deep-sea mining-associated metal exposure. [ABSTRACT FROM AUTHOR]

Transplantations of organisms in aquatic ecosystems play an important role in ecological restoration and commercial practices. However, success rates of these transplantations, especially when ecosystem engineers are involved, are often low. To enhance transplantation success, the promotion of self‐facilitation between transplants that mitigate environmental stressors is crucial. Besides, spatial patterns resulting from self‐facilitation can enhance ecosystem resilience. Using blue mussels as a model organism, we explored the possibility of increasing transplantation success in a subtidal ecosystem. We used biodegradable structures ("BioShell‐SMCs") to ameliorate self‐facilitating feedback mechanisms to overcome environmental stressors in the initial post‐transplantation phase, and to increase transplantation success by implementing large‐scale spatial configurations, mimicking natural mussel bed patterns. The structures are an innovation of traditional seed mussel collectors (SMCs) used in mussel cultivation. They consist of a biodegradable net based on a compound of aliphatic polyesters, filled with empty cockle shells around a coconut fiber rope. We tested whether different spatial configurations could increase transplantation success of mussel seed: low versus high density labyrinth pattern and banded pattern. The results of this experiment showed high losses (approximately 75%), with no significant variation between configurations. The lack of migration due to unexpected retention of the biodegradable net hindered the initiation of natural aggregations, resulting in increased competition among mussels. Besides, factors such as hydrodynamic dislodgement, burial and interannual variation likely contributed to the observed losses. While the BioShell‐SMC has not demonstrated large‐scale success, this research contributes to understanding the mechanisms that underlie successful transplantation strategies in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Dreissenid mussels (quagga and zebra mussels, Dreissena bugensis and polymorpha) continue to spread throughout inland waterbodies of North America. Although there are considerable management and mitigation efforts underway to prevent infestation of new waterbodies, there have been relatively few successful efforts to eradicate mussels once detected due to a lack of cost-effective treatments. Two potentially cost-effective molluscicidal agents, potassium chloride (KCl, also called muriate of potash) and copper (formulated as Earthtec QZ®), have successfully treated infested waters, but have varying efficacy under different water quality and temperature conditions, and to date have only been applied in moderate conductivity waters (defined here as < 400 µS/cm) common throughout North America. Natural resource managers need information on the efficacy of these chemicals in high conductivity waters more typical of riverine systems and arid climates, in addition to the range of water temperatures typically encountered in the field. We evaluated the doseresponse of quagga mussels to KCl and Earthtec QZ® in high conductivity water (≈ 700-1,400 µS/cm) across a range of temperatures (10, 18, 22 °C) to determine appropriate doses and treatment duration resulting in 100% mortality. Our data indicate that treatments in cool temperatures (i.e., 10 °C) may be challenging for eradication efforts in high conductivity waters because none of the KCl treatments and only one copper treatment resulted in 100% mortality within the experimental period. However, both KCl (> 200 ppm) and copper (120 and 180 ppb) were consistently able to induce 100% mortality in quagga mussels in warmer temperatures (i.e., = 18 °C) and thus may be good candidates for field scale application in high conductivity waters. The results of this study indicate that field-scale application should strongly consider environmental conditions during the period of application when selecting dosages and treatment duration. [ABSTRACT FROM AUTHOR]