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In this study, we investigated the impact of water temperature on pearl formation and the molecular mechanisms underlying this biomineralization process in the mussel Hyriopsis cumingii. In the laboratory experiment, recipient mussels received saibo grafts from donor mussels and then were cultivated at five temperatures (16, 20, 24, 28, and 32 °C) for 1 month. We found that speed of pearl formation varied with water temperature: there was no visible pearl granules at 16 and 20 °C, tawny pearl granules were collected at 24 °C and lustrous pearl granules were collected at 28 and 32 °C. The expressions of several nacreous layer matrix protein genes (hic22, hic24, HcTyr Hc-upsalin and Hcperlucin) at 28 °C and 32 °C were peaked on day 28, and the expressions of other nacreous layer matrix protein genes (hic52 and hic74) on day 28 were significant higher than day 14. In the natural environment, pearl deposition rate also increased as water temperature rose, and the optimum range for pearl growth in H. cumingii was between 28.3 and 30.3 °C. Expression of the prismatic layer-related matrix protein genes hic31 and both prismatic and nacreous layer-related matrix protein gene silkmapin was significantly high in winter, and expressions of the nacreous layer-related matrix protein genes (hic24, hic74, HcTyr, Hc-upsalin and Hcperlucin) were always higher during higher temperature seasons compared with winter. These results indicate that high water temperature can speed up pearl formation and further regulate matrix protein secretion to accelerate pearl nacre deposition.

Microplastic pollution is a growing global concern and a serious threat to aquatic life. Microplastics (MPs) have been found in the natural environment in the last few years. However, levels of microplastic pollution in aquaculture areas of Hainan Island have been less studied than in wild environments. Xincun bay (XC) and Gangmen bay (GM) are lagoons that are rich in fishery resources. Here, we investigated microplastic pollution in 8 surface seawater samples, 17 species of fish, and mussel samples from XC bay and GM bay, Hainan, China. The MPs were isolated from surface seawater, organisms and identified by microscopic, Raman spectroscopic and micro-Fourier Transform Infrared spectrometer methods. The mean abundance of MPs in seawater samples was 523 items/m3 and that of fish was 7.1 items/individual and the percentages of microplastics detected in the gastrointestinal tracts (GITs) and gill were 99% and 1%, respectively. MPs were also observed in the soft tissues of mussel samples with a mean abundance of 0.36 ± 0.81 items/individual. Most MPs were identified as polystyrene and their sizes ranged between 0.5 and 5 mm in both seawater and organism samples. Our results indicated that the uptake of microplastics by organisms was closely related to microplastic pollution in the aquaculture environment. Foam pollution is common in organisms and surface seawater in the aquaculture area of our study region, which provides a way for human exposure.

Understanding dreissenid mussel population dynamics and their impacts on lake ecosystems requires quantifying individual growth across a range of habitats. Most dreissenid mussel growth rates have been estimated in nutrient rich or nearshore environments, but mussels have continued to expand into deep, cold, low-nutrient habitats of the Great Lakes. We measured annual quagga mussel (Dreissena rostriformis bugensis) growth at 15 m, 45 m, and 90 m in Lake Ontario using caged mussels near Oswego, New York, USA from June 2018 to May 2019. Quagga mussel growth (starting size 12 mm) was greatest at 15 m (mean shell length increase = 10.2 mm), and was lower at 45 m (5.9 mm) and 90 m (0.7 mm). Caged mussels were obtained from near the 90-m site and those reared at 15 and 45 m developed thicker shells than those that were caged at 90 m. We observed relatively high colonization by quagga and, to a lesser degree, zebra mussels (Dreissena polymorpha) at 15 m, very few colonizers at 45 m, and none at 90 m. Higher growth potential, but low natural mussel densities observed at 15 m and 45 m suggest factors other than growth limit dreissenid abundance at these depths. The relatively slow dreissenid growth rates observed in offshore habitats are consistent with the gradual abundance increases documented in these zones across the Great Lakes and suggest new mussels that become established in these habitats may contribute to ecosystem effects for decades.

Enhancing the deposition of fragrance delivery systems contained in personal care products on target surfaces is crucial for increasing the longevity of scent, efficiently utilizing expensive functional compounds and limiting the generation of microplastics in domestic waste water. In this work, we designed and synthesized a new type of biomimetic macromolecules, chitosan-graft-L-lysine-L-DOPA (C-L-D), as a versatile biodegradable adhesion promoter to facilitate the deposition of biodegradable fragrance carriers on diverse surfaces including hair, cotton and skin. The C-L-D has hyperbranched chain architecture with many oligopeptide adhesive tentacles, each being a simple mimic of mussel adhesive proteins. It also exhibits unique amphiphilic characteristic. As a result, it could be facilely anchored on cargo-loaded poly(lactic-co glycolic acid) nanoparticle surface via self-assembly in the particle preparation process. The C-L-D-modified nanoparticles show significantly higher deposition efficiencies than polyvinyl alcohol- and chitosan-coated particles when deposited on the target surfaces in different aqueous media as the lysine and DOPA units are capable of providing multi-noncovalent interactions, including electrostatic, polar, hydrophobic interactions, and bidentate hydrogen bonds, with the target surfaces, and possibly also inducing oxidative cross-linking. A much higher retention rate of the C-L D-modified nanoparticles on cotton surface is also observed after washing with a soap solution, which could be attributed to the significant role played by bidentate hydrogen bonds. These findings suggest that C-L-D is a versatile biodegradable adhesion promoter and has the potential to be applied for various personal care applications and beyond. Agency for Science, Technology and Research (A*STAR) Accepted version This work was supported by Science and Engineering Research Council of the Agency for Science, Technology and Research (A*STAR) Singapore under AME domain IAF-PP Grant No. SERC A1786a0034.

In this study, we introduced an indigenous Korean muricid gastropod Reishia bronni (Dunker, 1860), a potential natural predator of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819), a well-known invasive alien species successfully settled down in Korea. From the survey on the Korean ports of the east coast between 2007 and 2011, we have observed the spread of R. bronni within the Mytilus galloprovincialis community. The observed decrease of the mussel density around the gastropod assemblage led us to the idea that R. bronni is the natural predator of M. galloprovincialis. To clarify such a predator-prey interaction between both species, we performed a field observation from two Korean ports in August 2012, keeping R. bronni and M. galloprovincialis individuals together into the cages for 18 days. Then, we counted the number of latter ones consumed and estimated the average time spent feeding per individual of R. bronni. We observed the positions of the drill holes made on the consumed shells by it. Our results showed that R. bronni is the active natural predator of M. galloprovincialis with the high feeding intensity and the unique foraging behavior targeting the lateral margin of the shell.

Uroporphyrinogen III synthetase (UROS) is an important enzyme involved in the structural formation of porphyrin, which is responsible for color intensity. A UROS homolog was isolated and characterized from the pearl mussel, Hyriopsis cumingii (HcUros). The HcUros cDNA was 858 bp in length with an open reading frame that encoded a 285 amino acid protein, which contained a conserved HemD domain. HcUros exhibited widespread tissue distribution, displaying particular enrichment in the mantle and haemolymph of purple mussels, compared to white mussels. In situ hybridization of HcUros in mantle tissue demonstrated that it was specifically expressed in the dorsal epithelial cells of the mantle pallia. Additionally, HcUros expression was upregulated following implantation of the pearl sac to produce pearls. The data suggest that HcUros contributes to shell pigmentation, and nacre formation and coloring in H. cumingii.

The biomineralization mechanism of mollusc shell has been studied for a long time, but there is a lack of understanding about the relationship between the shell formation in vitro and the signaling system in vivo. In this study, we cloned a novel shell matrix protein gene (hc-temptin), which only be characterized as a water-borne protein pheromone of molluscs in previous studies, from the freshwater mussel Hyriopsis cumingii. By bioinformatics analysis we found that temptin was a gene unique to the clade Lophotrochozoa, and it exists in all mollusc taxa except Cephalopoda. The current data supported the premise that temptin was generated in the early emergence of molluscs and that it maintained a high mutation rate to evolve relative independently. The specificity of hc-temptin expression in the mantle tissue suggests its potential to participate in biomineralization. Its sequence contained typical Ca2+ binding sites. Our experiments involving the pearl formation process, damaged shell repair process, and RNAi experiment showed that hc-temptin was a shell matrix protein that plays an important role in formation of the prismatic layer. The results of this study provided new insights about the origin of the temptin gene and its role in molluscs.

Considering the importance of hemocyte characterization for immunological studies, this work aimed to characterize the hemocyte types of Perna perna mussels combining transmission electron microscopy and flow cytometry with the classical optical microscopy. The results indicated four type of hemocytes: hyalinocytes, semigranulocytes, granulocytes and blast-like cells.

Freshwater drum (Aplodinotus grunniens) may be a predator of the invasive zebra mussel (Dreissena polymorpha), which established in Lake Winnipeg in 2013. In this study, the diets, trophic position, and growth of 51 freshwater drum collected in 2019 (six years post-zebra mussel invasion) were compared to 64 freshwater drum sampled in 2000. Benthic insect larvae were the dominant food items in both years. Although mollusks occur in high densities in Lake Winnipeg, they were only consumed by a few freshwater drum in either sample year. Zebra mussels were not a frequent prey item in 2019 as they were only consumed by four of the sampled freshwater drum. Stable isotope analysis of white muscle tissue yielded similar δ13C and δ15N values in both years and were consistent with a benthic, insectivorous diet. Length-at-age data derived from otoliths revealed that the 2019 population had at least an equal growth rate to the 2000 population. Weight-at-length data suggested that fish condition was greater in 2019 than in 2000, which coincided with increased benthic macroinvertebrate density in Lake Winnipeg. Based on these findings, Lake Winnipeg freshwater drum continue to feed predominantly on insect larvae and not zebra mussels.

Blooms of the dinoflagellate Alexandrium catenella, which produces Paralytic Shellfish Toxins (PST), generate serious socio-economic consequences for mariculture in Chile, especially for the production of Mytilus chilensis and other bivalves. Palliative strategies, such as the depuration of mussels in enriched water with chitosan offer encouraging prospects against the advance of contaminated areas and toxin persistence. Adult mussels were fed with A. catenella for 20 days and then were allowed to depurate using chitosan as facilitator, for the same period. Intoxicated mussels showed a reduction in feeding activity and rapid PST accumulation in 20 days (C = 451.5t + 1,673.6, R2 = 0.55 p = 0.008). Not enough evidence was found to indicate a positive effect of chitosan in mussel depuration after 20 days (C = −311.1t + 8,462.4, R2 = 0.8 p = 0.001). At the end of the study, toxicity was higher than 800 μg STX eq kg−1. C2 and GTX4 analogues were the most abundant in the dinoflagellate strain, while C2 and C1 were the most accumulated in mussels. The presence of C1 was notorious during depuration, as the persistence of GTX2,3. GTX5 was only detected in A. catenella, while STX was only present in mussels. Mussel sensitivity to the presence of the toxic dinoflagellate was observed in the present study. The biotransformation, selective elimination and epimerization processes were deduced from intoxication and depuration experiments.

The invasive zebra mussel, Dreissena polymorpha (ZM), established in Europe for a long time, has recently been joined and commonly outcompeted by a new invader, the quagga mussel, Dreissena rostriformis bugensis (QM). To identify factors contributing to this displacement, we studied behavioural differences between the species: aggregation, movement, and responses to conspecifics, congeners and their alarm cues. Compared to ZM, QM were more aggregated and less motile, crawling shorter distances for a shorter time at a slower speed. Conversely, QM exhibited more nonlocomotor movements. Both species aggregated and burrowed less and showed more nonlocomotor movements in response to conspecific and heterospecific alarm cues. They also moved shorter distances in the presence of conspecific alarm cues. ZM delayed their locomotion and nonlocomotor movements, whereas QM started locomotion earlier in the presence of both alarm cues. Mussel responses to living heterospecifics resembled those to alarm cues. In mixed-species aggregations, ZM attached to conspecifics more often than to QM shells, whereas QM were nonselective. To summarize, QM are less mobile, less selective regarding attachment site and more aggregated than ZM. This allows QM to perform better in mixed-species assemblages by spending less energy on relocation and overgrowing ZM to a higher extent than vice versa. Both species responded to heterospecific signals, which is helpful in mixed-species assemblages, particularly in novel areas occupied by these invasive species. Nevertheless, similar responses to alarm cues and living heterospecifics suggest a negative interaction between the congeners.

Contaminants of emerging concern (CECs) are prevalent in aquatic landscapes and may be a factor in population declines of aquatic and terrestrial fauna. Yet, there are limited data to assess the impacts of CECs to species. Understanding CEC impacts is particularly important for imperiled freshwater mussels which provide valuable ecosystem services. CEC exposure of freshwater mussels was characterized by evaluating sites with and without the federally endangered mussel (Villosa fabalis) in three subwatersheds of the Maumee River, Ohio, USA, a tributary of the Great Lakes Basin. Analyses of water, sediment, and tissue concentrations of two common mussels (Eurynia dilatata and Lampsilis cardium) indicated different CEC exposures across all 6 sites. Distinct CEC signatures were found across the three media types suggesting as mussels interact with water and sediment they may be experiencing different exposure concentrations and mixtures of CECs at different life stages. Of the 83 CECs which were detected, agricultural CECs dominated sediments, pharmaceuticals were common in tissues and water, and 16 of the 83 CECs were found co-occurring in mussel tissue, water, and sediment. There were no species differences in the CEC signatures indicating all mussels, including species of concern, may be experiencing similar exposure. Comparisons to known CEC standards indicate some exceedances in the Maumee watershed including locations of federally listed mussel species. This study provides evidence of the complexity of CEC mixes in a Great Lakes watershed and the need to understand how CECs impact declining aquatic fauna.

The effects of lecithin addition at different concentrations (0-2.0%) on the physicochemical and emulsifying properties of mussel water-soluble proteins (MWP) were investigated. In solution system, low lecithin concentration (0.5%-1.0%) induced the aggregation and increased turbidity of composite particles. Lecithin addition caused changes in secondary structure and induced partial unfolding of MWP. Hydrophobic interactions between MWP and lecithin may contribute to the exposure of chromophores and hydrophobic groups of MWP. The interfacial tension decreased with lecithin addition. However, at a high lecithin concentration (1.5%-2.0%), the degree of aggregation and state of unfolding alleviated due to competitive adsorption. In emulsion system, with the low concentration of lecithin addition (0.5%-1.0%), droplet size and surface charge of emulsion decreased. The emulsion activity index, emulsion stability index, percentage of adsorbed protein increased. Both creaming stability and viscoelastic properties improved. At an intermediate lecithin concentration (1.0%), the emulsion showed the highest physical stability, while further addition of lecithin caused a slight deterioration in emulsifying properties. Overall, these results indicated the possibility that the lecithin-MWP mixed emulsifiers can be used to obtain emulsions with desirable properties.

Nanosized calcium deficient carbonated apatite was synthesized from three different natural resources, namely chicken eggshells (calcite), cuttlefish bones (aragonite) and mussel shells (aragonite/calcite). The calcium precursors were ball-milled in (NH4)2HPO4 or H3PO4 – containing aqueous medium for different times and then dried at temperatures ranging from 20 °C to 150 °C. The formation of hydroxyapatite (HA) is shown to be strongly affected by such treatment, the amount of synthesized HA increasing with temperature. Aragonite from cuttlebones and the aragonitic fraction of mussels is found to be transformed more easily with respect to the calcite from eggshells. The reaction is also favored by an acidic milling media with respect to basic one. The feasibility of the synthesis process at nearly room temperature described in the present work has interesting potentialities in the retention of the organic portions of the original biological resource in the produced nanometric inorganic compound.

The present study aims to evaluate the effect of dietary fulvic acid supplementation on the accumulation of Pb and Cd and the growth performance of Nile tilapia Oreochromis niloticus fed with diets containing green mussel with high Cd and Pb content. Nile tilapia juveniles with a mean body weight of 8.9 ± 0.6 g were randomly distributed into 15 aquarium units (100 L, 17 fish per aquarium). Five experimental diets were formulated to contain 10% mussel meal with high Pb and Cd concentrations, and five levels of fulvic acid, i.e. 0, 100, 200, 400 and 800 mg kg−1 and fed to the fish to the satiation level for 60 days of culture. The consumption of diets containing Pb and Cd resulted in the accumulation of these heavy metals in the fish, however, fulvic acid dietary supplementation could reduce the accumulation of the heavy metals. Furthermore, the dietary supplementation of fulvic acid up to 400 mg kg−1 had significantly improved the fish growth performance and feed utilization. In conclusion, the dietary supplementation of fulvic acid of 200 mg kg−1 could be recommended to prevent Pb and Cd accumulation and to enhance the growth of Nile tilapia fed with diet containing heavy metals.

In this study, the removal of tetracycline from aqueous solutions with chitosan obtained from mussel shells was optimized and investigated using responce surface methodology. For this aim, the central composite design was used to optimize the four variable factors (sorbent dosage (0.4–1.0 g), time (20−60 min), temparature (10−30 °C) and initial TC concentration (50−100 mg/L)) for the removal of TC from aqueous solutions by chitosan obtained from mussel shells. According to the RSM analysis results, optimum conditions for maximum TC removal efficiency were determined as 90.5 mg/L for initial TC concentration, 35.9 min for time, 29.9 °C for temperature and 0.4 g for sorbent dosage. It was observed that the tetracycline was crystallized on mussel shells. According to the results of XRD after adsorption, the content of mussel shells were observed as 60% calcite, 5.6% overite, 9.4% aragonite and calcium hydroxide 25%, respectively. As a result, experiments showed that chitosan obtained from mussel shells were a good adsorbant for tetracycline removal from aqueous solutions.

Confronting the complexity of marine biofouling, no single ecofriendly technology has been reported for efficient anti-biofouling. Combination of multiple antifouling factors should be one of the strategies for strengthening the anti-biofouling performance. Here we synthesized quaternary ammonium modified SiO2 nanoparticles (QAS-SiO2) and incorporated them into self-polishing polymer (SP) to get the coatings combining self-renewal ability, micro-nano structured topography, and bactericidal function. The coatings acquired underwater superoleophobic surface after immersion in artificial seawater due to their micro-nano structured surface together with the hydrolyzed SP. In comparison with unmodified SiO2, QAS-SiO2 had better compatibility with SP and caused less increment of self-polishing rate. Synergistic antifouling effect was interestingly observed between self-renewal ability and bactericidal function in both the laboratory assay based on the adhesion of Shewanella loihicas and natural field trial. The micro-nano structured topography contributed to underwater superoleophobicity but did not exhibit its impact on antifouling performance. QAS-SiO2 can also slightly inhibit the adhesion of diatoms and reduce the settlement of plantigrades of the mussel. In addition, we also demonstrated the coatings with lower quantity of biofilm exhibited less settlement of plantigrades of mussel.

The critical problem associated with the underwater mussel adhesive catechol-based 3,4-dihydroxy-L-phenylalanine (DOPA) is its sensitivity to oxidation. To overcome this problem, mussels underwent etching in the presence of acidic pH conditions (

Climate change is expected to cause significant changes to rocky shore diversity. This study used outdoor mesocosms to test the predictions that warming and ocean acidification will alter the responses of native Trichomya hirsuta and introduced Mytilus galloprovincialis mussels, and their associated communities of infauna. Experiments consisted of orthogonal combinations of temperature (ambient 22 °C or elevated 25 °C), pCO2 (ambient 400 μatm or elevated 1000 μatm), mussel species (T. hirsuta or M. galloprovincialis), and mussel configuration (native, introduced, or both), with n = 3 replicates. Elevated pCO2 reduced the growth of T. hirsuta but not that of M. galloprovincialis, and warming and pCO2 influenced the infauna that colonised both species of mussels. There was a reduction in infaunal molluscs and an increase in polychaetes; there was, however, no effect on crustaceans. Results from this study suggest that climate-driven changes from one mussel species to another can significantly influence infaunal communities.

Little information is available on host-parasite relationships between bivalves and larval nematodes. Herein, we describe nematode larvae (likely stage 2) in the infraorder Ascaridomorpha infecting the foot, intestine, and mantle of a freshwater mussel (Alabama rainbow, Villosa nebulosa [Conrad, 1834]) and detail histopathological changes to infected tissues. A total of 43 live mussels from the South Fork of Terrapin Creek, Alabama, were collected between 2010 and 2014, with 14 sectioned for histopathology and 29 dissected. Of the 14 sectioned mussels, 5 appeared to be uninfected, and 7, 1, and 1 had histozoic infections observed in the foot and intestine, intestine only, and mantle edge and foot, respectively. Twenty-three of 29 (79%) of the mussels dissected were infected by live nematodes, and mean nematode abundance was 8.3 (CL = 5.23–13), with 2 mussels infected with >100 nematodes each. Thus, with a total of 32 of the 43 collected mussels observed with nematodes, overall infection prevalence was 74.4% (CL = 0.594–0.855). The 18S rDNA of this nematode was 99% similar to that of several ascaridids (species of Kathlaniidae Lane, 1914 and Quimperiidae Baylis, 1930) that mature in aquatic/semi-aquatic vertebrates; the recovered 18S phylogenetic tree indicated this nematode from V. nebulosa shares a recent common ancestor with Ichthyobronema hamulatum (Ascaridomorpha: Quimperiidae; GenBank Accession Number KY476351). Pathological changes to tissue associated with these infections comprised focal tissue damage, but a cellular response was not evident. The Alabama rainbow possibly represents an intermediate or paratenic host. Given these results, the nematode is likely not pathogenic under normal stream conditions; however, high intensity infections in the foot could inhibit pedal extension and retraction; which would have demonstrable health consequences to a freshwater mussel. Based on our review of the bivalve mollusc parasite literature, a collective biodiversity of 61 nematodes reportedly exhibit some degree of symbiosis (from commensal to parasitic) with 21 bivalves (28 nematode spp. from 17 marine bivalve spp.; 33 nematode spp. from 4 freshwater bivalve spp.); only four records exist of putatively parasitic nematodes from Unionida. The present study represents the first description of a nematode species that invades the tissues of a Unionidae species., Graphical abstract Image 1, Highlights • Pathological changes comprised focal tissue damage but a cellular response to the parasites was not evident. • Nematodes from infected tissues appear to be second stage larvae of Ascaridomorpha. • The small subunit rDNA sequence of this nematode was 99% similar to species of Kathlaniidae and Quimperiidae. • The nematode is likely not pathogenic under normal stream conditions.

Marine mussels have been used widely as biomonitors of coastal contamination in many countries. Due to the restrain of their geographical distributions, it is often necessary to employ more than one species of mussels within a large-scale biomonitoring program. In the present study, we compared the differences of copper (Cu) bioaccumulation in three species of marine mussels (green mussel Perna viridis , blue mussel Mytilus edulis , and hard-shelled mussel Mytilus coruscus ) widely distributing along the Chinese coastal waters, under identical Cu exposure conditions. Over the 21-days exposure to dissolved Cu, the green mussels and blue mussels exhibited comparable newly accumulated Cu concentrations, possibly due to their comparable Cu uptake rate constant k u (blue mussel, 0.573 L g −1 d −1 ; green mussel, 0.530 L g −1 d −1 ) and efflux rate constant k e (blue mussel, 0.053 d −1 ; green mussel, 0.065 d −1 ). In contrast, there was no net Cu accumulation in the hard-shell mussels, which may be accounted by the lower k u (0.394 L g −1 d −1 ) but higher k e (0.081 d −1 ) than the other two mussel species. Further subcellular distribution analyses showed that the cellular debris and metallothionein-like protein (MTLP) fraction were the key binding sites for Cu, and the MTLP fraction may act as a main contributor in Cu regulation and elimination in the blue mussels and hard-shell mussels. There was no strong evidence that the subcellular partitioning and dynamics of Cu in the mussels were responsible for the difference underlying the Cu accumulation in the three species of mussels. Our comparative study thereby suggested that it may be feasible to directly compare the Cu bioavailability in the green mussels and blue mussels based on their Cu biomonitoring data. Cu biomonitoring data from the hard-shell mussels may underestimate the actual Cu bioavailability of the sampling area given its much stronger regulation of Cu bioaccumulation as compared to the other two mussel species.

Freshwater bivalve shells may record inter-annual fluctuations in water chemistry, which in turn may archive variations in solute load due to pollution or discharge events. Here, using weekly surface water chemistry collected at two locations and shells of Lampsilis cardium grown in the surface water we investigate if the Mg/Ca, Mn/Ca, Sr/Ca, and Ba/Ca ratios measured at high resolution in the shells on an intra-annual time scale consistently reflect the chemistry of the surface water. Two relationships appear highly correlated, Sr/Cacarb and Sr/Cawater, and Mn/Cacarb and temperature. Ba/Cacarb correlated strongly with Ba/Cawater in one shell but temperature in another shell yielding inconclusive results. Mn/Cacarb and Mg/Cacarb were not strongly correlated with elemental ratios in the water, but Mn/Cacarb did show variable, weak to moderate correlation with pH. We found consistent partition coefficient (DMe) values between individual shell samples grown in the same water with mean DMg = 0.0006, DMn = 17, DBa = 0.13, and DSr = 0.176. Sr/Cacarb and Sr/Cawater exhibited the strongest, most consistent correlation with partitioning coefficients that were consistent with published values, suggesting Sr/Cacarb can be used as a proxy for Sr/Cawater in freshwater mussels.

Marine biofouling by the swiftly spreading invasive mussel (Musculista senhousia) has caused serious ecological and economic consequences in the global coastal waters. However, the fate of this highly invasive fouling species in a rapidly acidifying ocean remains unknown. Here, we demonstrated the impacts of ocean acidification within and across generations, to understand whether M. senhousia has the capacity to acclimate to changing ocean conditions. During the gonadal development, exposure of mussels to elevated pCO2 caused significant decreases of survival, growth performance and condition index, and shifted the whole-organism energy budget by inflating energy expenses to fuel compensatory processes, eventually impairing the success of spawning. Yet, rapid transgenerational acclimation occurred during the early life history stage and persisted into adulthood. Eggs spawned from CO2-exposed mussels were significantly bigger compared with those from non-CO2-exposed mussels, indicating increased maternal provisioning into eggs and hence conferring larvae resilience under harsh conditions. Larvae with a prior history of transgenerational exposure to elevated pCO2 developed faster and had a higher survival than those with no prior history of CO2 exposure. Transgenerational exposure significantly increased the number of larvae completing metamorphosis. While significant differences in shell growth were no longer observed during juvenile nursery and adult grow-out, transgenerationally exposed mussels displayed improved survival in comparison to non-transgenerationally exposed mussels. Metabolic plasticity arose following transgenerational acclimation, generating more energy available for fitness-related functions. Overall, the present study demonstrates the remarkable ability of M. senhousia to respond plastically and acclimate rapidly to changing ocean conditions.

This study investigates the combined effects of increased temperatures and copper on the early live stages of the Mediterranean mussel Mytilus galloprovincialis and the blue mussel Mytilus edulis as well as their hybrids. For this purpose, developmental abnormalities was measured after 48 h of exposure as well as a battery of oxidative stress markers such as, antioxidant enzyme activities, lipid peroxidation measured as malondialdehyde accumulation (MDA) and metallothionein contents (MT) and related gene expression pattern. Embryotoxicity and metal accumulation in tissues of mussel larvae exposed to a sublethal concentration of copper (10 μg/L) along with a slight temperature increase from 18 °C to22 °C were significantly increased after 48 h of exposure. Co-exposure to Cu and elevated temperatures significantly increased the antioxidant enzyme activities termed as, glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD) and being maintained at 22 °C only in pure M. galloprovincialis (PG) larvae and female galloprovincialis x male edulis hybrid larvae (HFG). A significant decrease in mRNA abundance of cat, sod, gst gene transcription levels was showed in the same species. Furthermore, metallothionein accumulation increased significantly in PG D-larvae exposed to copper at 22 °C. The same pattern was observed in term of gene expression of MTs cognates (mt-10 and mt-20). Significant increase of MDA levels in pure M. edulis (PE) larvae and their female M. edulis x male M. galloprovincialis hybrid larvae (HFE) combined with a low MTs content were observed. Overall, this study provides clues about the relatively higher resistance and resilience of M. galloprovincialis species compared to M. edulis species under environmental pollution and future climate change scenarios.

Background Mussel (Mytilus edulis) by-products consist of materials including byssus threads, shell and discarded whole mussels containing meat. Mussels are a rich source of lipids, proteins, carbohydrates, minerals and other bioactives. This nutrient rich waste can be effectively exploited for high value applications including as functional food and feed ingredients, feed supplements, enzymes and other fine chemicals. Scope and application The present review paper collates data on (i) the total global production of Mytilus edulis and fractionated by-products available for processing and (ii) potential treatment and extraction strategies used to obtain value-added products. The review also discusses other macromolecules besides proteins including lipids, carbohydrates and minerals and possible uses of these in food packaging, as food preservation agents or as bio-adhesives. Key finding and conclusions Mussel by-products represent a reserve of valuable components like bioactive proteins, polyunsaturated fatty acids, mineral compounds, pigments, enzymes and much more. Though researchers have explored various mussel fractions for target applications, a holistic approach using bioprocessing techniques needs to be employed at a commercial scale. Unless researchers, primary manufacturers and technologists develop an integrated approach to utilize mussel by-products, there will be negative environmental and economic impact. Sustainable by-products supply and scalable technologies will ensure successful bioconversion of by-products into high value end products.

Paralytic shellfish toxins (PSTs) are a group of the most harmful neurotoxins distributed worldwide. Marine organism samples, including mollusks, crustaceans and fish, collected from 11 sites around the coastal water of the South China Sea, were analyzed in terms of the PST and toxicity via high–performance liquid chromatography. The PST geographical distribution, detectable rate for PST and toxin content all increased slightly from 2006 to 2008 to 2015. High PST content with more than 2 nmol g−1 appeared in Shantou (ST), Shanwei (SW), Zhanjiang (ZJ), Beihai (BH), Xuwen (XW), Haikou (HK), Dongfang (DF), Wanning (WN) and Sanya (SY). Low PST content with less than 2 nmol g−1 appeared in Shenzhen (SZ) and Yangjiang (YJ). High PST toxicity over the safety limit 800 μg STXeq/kg appeared in ST, SW, ZJ, BH, DF, SY and XW. PST has significant seasonal characteristics and was mostly detected in spring, early summer (March–June) and autumn (September–November) in the coastal water of the South China Sea. PST was usually detected in some specific species of scallop, mussel, bloody clam, hard clam, razor clam, oyster, crab, shrimp and fish. Toxin profile variation of marine organism samples was influenced greatly by species, sampling time and site.

Analysis of ∼47,500 freshwater mussel shells, representing 34 taxa, recovered from late Holocene archaeological sites located along the Upper Mississippi River in southwestern Wisconsin affords the opportunity to address variation in exploitation of shellfish by Woodland Tradition foragers (ca. 2,000–900 B.P.) and Oneota Tradition agriculturalists (ca. 800–500 B.P.). Woodland foragers targeted dense beds from which large numbers of mussels could be harvested relatively quickly. It is hypothesized that meat from mussels was dried, packaged, and transported to interior, upland locations to help alleviate anticipated food-resource deficits in the winter. Oneota agriculturalists harvested mussels in modest numbers from variety of riverine contexts for food and preferentially collected thick to medium-thick shelled taxa to serve as a source of temper in pottery manufacture.

Reversing the effects of secondary salinization, and its impacts on aquatic biodiversity, is a growing global challenge, and particularly prevalent in Mediterranean-climate regions. Remnant freshwater tributaries in salinized landscapes provide significant biodiversity values, including discrete areas of refuge, dilution of salinized reaches, and potential source populations for recolonisation. The importance of these areas for aquatic fauna is widely accepted but rarely evaluated in the field. This study explored how spatial distribution of southwestern Australia's only freshwater mussel species, Westralunio carteri, has responded to the ongoing salinity trend in the Kent River catchment. Our results showed that salinity in the river has begun to reverse following improved catchment management, and also detected the first evidence of an associated recovery of the freshwater mussel population. Mussels in the mainstem were limited to sites around and downstream of a permanently flowing freshwater tributary, suggesting that dilution from this source provides a refuge in the lower reach. At two of those sites, all individuals were

Microplastics have been found to adhere to the surface of specific tissues or organs other than being ingested by the organisms. To further test the hypothesis that microplastics might get into specific body parts of organisms, mussel byssus was chosen as a target subject in the present study. In the field investigation, microplastics were found in mussel byssus, and the abundance of microplastics was 0.85-1.02 items/individual mussel and 3.69-9.16 items/g byssus, but the location of microplastics in byssus was not easily determined. Therefore, we simulated environmental conditions in the laboratory for mussels to form fresh byssus in the presence of microplastics. Three types of man-made microplastics (Polystyrene beads, Polyamide fragments, and Polyester fibers) were found in newly formed byssus of mussels after exposure to these test materials. We observed that microplastics not only adhered to the surface but also fused into the byssus of mussels. Since byssus is important for the well-being of mussels, the incorporation of microplastics into the byssus might impair the function of byssus. To the authors' best knowledge, this is the first study to show that microplastics can contact and fuse with the byssus of mussels during their formation, suggesting possible alternations for mussels to grip and interact with microplastics in the aquatic environments.

Stable carbon isotope ratios (δ13C) of mussel soft tissues have been widely used to characterize baseline δ13C isoscapes and identify carbon sources at the base of coastal food webs. Extending soft tissue δ13C records back in time, however, is extremely challenging due to very limited sample availability. Here, we test if the stable carbon isotopic composition of periostracum (the outermost organic layer of the shell) in the Mediterranean mussel (Mytilus galloprovincialis) can be used as an environmental archive, similar to soft tissue records. In general, spatial and seasonal variations of periostracum δ13C values are comparable to those of soft tissues, but apparently the latter are more time-averaged and smoothed. Irrespective of such offset, there is a significant linear correlation between mussel periostracum and soft tissue δ13C values (R2 = 0.608, p

The invasion of exotic species in aquatic environments is one of the several disturbance factors responsible for altering the dynamics of fish communities. The golden mussel Limnoperna fortunei was first recorded in the upper Uruguay river, Brazil, in 2012 and, since then, it has been needed to discuss and evaluate how this invasive species interferes with the dynamics of the ten most abundant fishes of this region. Literature lacks works that investigate how to model and control the effect of such kind of invasion. This paper proposes a polynomial-nonlinear state-space representation to model the dynamics of the these fish communities, whose parameters are identified with the use of Least Squares procedures, considering in loci collected data from 2007 to 2016. This work also evaluates quantitatively, by relying on simulation results, how the (sudden) presence of the golden mussel medelled with the aquatic life of the upper Uruguay river. The obtained model allows some ambitious automatic control objectives. Using a Nonlinear Model Predictive Control (NMPC) approach, an automatic controller is designed to determine how much and how often the golden mussel should be removed from the water in order for the most affected species to once again exhibit sustainable life conditions, in terms of its K Condition Factor and abundance. The NMPC strategy is synthesized considering performance constraints and piecewise-constant control trajectories. By relying on simulation results, this work elucidates how an automatic controller could be implemented as management policies established by environmental agencies to gradually restore the fish ecological balance of the upper Uruguay river, previously unsettled by an exotic invasor.

During their lifecycle, many marine organisms rely on natural adhesives to attach to wet surfaces for movement and self-defence in aqueous tidal environments. Adhesive proteins from mussels are biocompatible and elicit only minimal immune responses in humans. Therefore these proteins have received increased attention for their potential applications in medicine, biomaterials and biotechnology. The Asian green mussel Perna viridis secretes several byssal plaque proteins, molecules that help anchor the mussel to surfaces. Among these proteins, protein-5β (Pvfp-5β) initiates interactions with the substrate, displacing interfacial water molecules before binding to the surface. Here, we established the first recombinant expression in Escherichia coli of Pvfp-5β. We characterized recombinant Pvfp-5β, finding that despite displaying a CD spectrum consistent with features of a random coil, the protein is correctly folded as indicated by MS and NMR analyses. Pvfp-5β folds as a β-sheet–rich protein as expected for an epidermal growth factor (EGF)-like module. We examined the effects of Pvfp-5β on cell viability and adhesion capacity in NIH-3T3 and HeLa cell lines, revealing that Pvfp-5β has no cytotoxic effects at the protein concentrations used and provides good cell-adhesion strength on both glass and plastic plates. Our findings suggest that the adhesive properties of recombinant Pvfp-5β make it an efficient surface coating material, potentially suitable for biomedical applications including regeneration of damaged tissues.

Freshwater mussels are widely used in the monitoring of pollution because they are filter-feeding, long-lived animals that tend to accumulate metals in their shells. The temporal scale of such studies can reach thousands of years, since the composition of shells preserves them against decay. This allows us to reconstruct past environmental conditions and to compare current environmental conditions to those prevalent thousands of years ago. Here we assessed metal concentrations (Ca, Cd, Cr, Cu, Fe, Hg, Ni, Pb and Zn) in recently harvested mussel shells and mussel shells found by archaeologists, and tested the hypothesis that levels of some metals are higher in today's shells, reflecting increasing anthropogenic impact. We observed lower metal concentrations (with the exception of Cd) in shells found by archaeologists (n = 35) than in recently harvested mussel shells (n = 14) (Unio crassus, Unio pictorum, Unio tumidus) in the same water bodies. There were no significant differences in metal levels among species in shells found by archaeologists, while in recently harvested mussels almost all metals for which we tested were found in their highest levels in Unio crassus. The results suggest that metal concentrations in prehistoric times were lower than today, which probably reflects human impact, rather than changes in the geochemical structure of rocks. The results also revealed that metal transfer between mussel shells and surrounding deposits does not occur. We therefore suggest that they might be successfully used as independent bioindicators.

Pseudoalteromonas is widely distributed in the marine environments and the biofilms formed by Pseudoalteromonas promote settlement of many species of invertebrates. Here, we show the complete genome of Pseudoalteromonas atlantica ECSMB14104, which was isolated from biofilms formed in the East China Sea and exhibited inducing activity on the Mytilus coruscus settlement. Complete genome of this strain containsa total of 3325 genes and the GC content of 41.02%. This genomic information is contributed to molecular mechanism of P. atlantica ECSMB14104 regulating mussel settlement.

The combined effects of seawater acidification and the non-steroidal anti-inflammatory drug diclofenac on haemocyte parameters of the mussel Mytilus galloprovincialis and the clam Ruditapes philippinarum were investigated for the first time. Animals were maintained for one week (T0) in natural pH condition (8.1) and two reduced pH values (pH −0.4 units and pH −0.7 units). Bivalves were then exposed for additional 14 days (T1 and T2) to the three experimental pH values in both the presence and absence of environmentally realistic concentrations of diclofenac (0.05 and 0.50 μg/L). To assess potential impairment in immunosurveillance, haemocyte parameters (total haemocyte count, haemocyte volume and diameter, Neutral Red uptake, haemocyte proliferation and lysozyme activity) were measured after 7, 14 and 21 days of exposure to differing pH value or pH/diclofenac combinations. In both species, pH affected the whole haemocyte data set at all sampling times, influencing most of the parameters measured at T0 and T1 in clams, and at T2 in mussels. Conversely, in both species diclofenac affected the overall haemocyte response at T2 only. However, in R. philippinarum a higher number of haemocyte parameters were significantly influenced even at T1. A significant interaction between pH and diclofenac was mainly evident in mussels, affecting haemocyte size and lysozyme activity at both T1 and T2. Overall, the results obtained demonstrated that the experimental conditions tested can alter markedly haemocyte parameters in marine bivalves.

The effect of water temperature on early-life development, growth and survival of the freshwater mussel, Hyriopsis bialata, was studied under controlled conditions. Gravid female mussels carrying gastrula embryos or early glochidia larvae were reared at 4 temperatures (25, 28, 31 and 34 °C) until they released mature glochidia; glochidia were then allowed to develop into juveniles. The highest survival rate of glochidia released from mussels carrying gastrula embryos was at 25 °C (91.4%), while survival for glochidia released from mussels carrying early glochidia larvae ranged from 83.2–91.3%. Average larval development time for gravid females carrying gastrula embryos or early glochidia larvae was between 5.0 and 9.2 days and 2.6–3.6 days, respectively. The survival of glochidia cultured to early juveniles in artificial medium was high in gravid mussels with gastrula embryos originally reared at 25 °C (93.9%) or 28 °C (93.6%), but was markedly decreased when originally reared at 31 °C (49.6%), while survival rates of those in gravid mussels with early glochidia larvae originally reared at 25, 28 or 31 °C were 92.3, 90.2 and 87.7%, respectively. The average transformation period from glochidia to early juvenile was 8–11 days, regardless of the temperature. Juveniles were reared for 1 month, and survival and length were measured. For glochidia released from gravid females with gastrula embryos, survival (85.7%) and length (0.49 ± 0.05 mm) were highest when originally reared at 25 °C, and both measures were significantly decreased at 28 and 31 °C. For glochidia released from gravid females carrying early glochidia larvae, survival (82.2%) and length (0.45 ± 0.06 mm) were highest when originally reared at 28 °C and lower when reared at 25 or 31 °C. Our results indicate that the optimal water temperature for culturing gravid female mussels carrying gastrula embryos or early glochidia larvae was 25 and 28 °C, respectively. These temperatures allowed high juvenile survival and growth.

In the last decade different approaches have been applied for water remediation purposes, including the use of nanoparticles (NPs) to remove metals and metalloids from water. Although studies have been done on the toxic impacts of such NPs, very scarce information is available on the impacts of water after decontamination when discharged into aquatic environments. As such, in the present study we aimed to evaluate the ecotoxicological safety of seawater previously contaminated with arsenic (As) and remediated by using manganese-ferrite (MnFe2O4-NPs) NPs. For this, mussels Mytilus galloprovincialis were exposed for 28 days to different conditions, including clean seawater (control), As (1000 μg L-1) contaminated and remediated (As 70 μg L-1) seawater, water containing MnFe2O4- NPs (50 mg L-1) with and without the presence of As. At the end of exposure, concentrations of As in mussels tissues were quantified and biomarkers related to mussels' metabolism and oxidative stress status were evaluated. Results revealed that mussels exposed to water contaminated with As and to As+NPs accumulated significantly more As (between 62% and 76% more) than those exposed to remediated seawater. Regarding biomarkers, our findings demonstrated that in comparison to remediated seawater (conditions a, b, c) mussels exposed to contaminated seawater (conditions A, B, C) presented significantly lower metabolic activity, lower expenditure of energy reserves, activation of antioxidant and biotransformation defences, higher lipids and protein damages and greater AChE inhibition. Furthermore, organisms exposed to As, NPs or As+NPs revealed similar biochemical effects, both before and after water decontamination. In conclusion, the present study suggests that seawater previously contaminated with As and remediated by MnFe2O4-NPs presented significantly lower toxicity than As contaminated water, evidencing the potential use of these NPs to remediate seawater contaminated with As and its safety towards marine systems after discharges to these environments.

Anthropogenic subsidies to natural systems can influence the diet of mobile omnivore species and co-occurring species. This study assessed if fall-off from mussel aquaculture subsidized wild populations of mobile scavengers and predators, such as the commercially important lobster Homarus americanus. A Bayesian stable isotope-mixing model with parameters determined from the literature and from a 105 days laboratory feeding experiment was applied to wild lobsters to determine how important the various food sources were in these lobsters, especially mussel fall-off. Isotopic values were mainly affected by lobster size with model outputs indicating that large lobsters (>80 mm cephalothorax) fed mainly on mussels from the mussel farm (46% of the diet) while small ones fed mostly on the rock crab Cancer irroratus (99%). The contribution of mussel subsidies to the lobster's diet was thus size-specific and direct (i.e. through mussel fall-off and not through co-occurring species such as rock crab). The absence of a link between food sources and lipid energy content in lobsters suggested that the reduction of rock crab consumption would have to be more drastic to affect the general health of large lobsters in the short term.

In the Great East Japan Earthquake of 11 March 2011, a magnitude 9.0 earthquake and accompanying tsunami struck the Tohoku region of Japan. The tsunami washed away old equipment containing polychlorinated biphenyls (PCBs) stored in the region's factories, and these PCBs may have leaked out of their casings into the marine environment. In this study, we evaluate marine PCB contamination by comparing mussels collected before (in 2005) and after (June 2011) the tsunami. PCB contamination levels were significantly elevated in mussel samples collected after the tsunami in June 2011 (3 months after the tsunami). This indicates that PCBs (specifically, formulation KC-400) leaked out of old equipment swept away by the tsunami and accumulated in mussels. PCBs were estimated to have an environmental half-life (EHL) in mussels of 4 months. Our results show that an earthquake and subsequent tsunami can cause elevated PCB contamination in the marine environment.

Titanium dioxide nanoparticles (TiO2 NPs) are widely used in various products and inevitably released with different sizes and forms into aquatic environment. The purpose of this study was to assess the differential immune toxicity of TiO2 NPs with size difference on mussel hemocytes using flow cytometry (FCM) assays. Hemocyte parameters, including total hemocyte count (THC), hemocyte mortality (HM), phagocytosis activity (PA), lysosomal content (LC), esterase activity (EA), mitochondrial number (MN), mitochondrial membrane potential (MMP) and reactive oxygen species content (ROS) were evaluated in the mussels Mytilus coruscus exposed to two types of TiO2 NPs (25nm & 100nm: 0.1, 1, 10 mg/L, respectively). In general, size- and concentration-dependent toxicity was pronounced with 25nm-NP and highest concentration (10mg/L) being the most toxic. Alhough a slight recovery from the TiO2 exposure was observed, significant carry-over effects were still detected. These results highlight the importance of differential size effects of metal oxide NPs on toxicity mechanisms in aquatic animals.

There is little information on the microbial communities associated with modified atmosphere (MA)-packaged live mussels. There is also a dearth of information on how pre-packaging depuration modifies the microbial communities and spoilage of live mussels. Amplicon sequencing was used to describe spoilage microbial succession in MA-packaged live mussels during storage at 4 °C. Proteobacteria, Cyanobacteria and Firmicutes were the three major phyla observed in the mussel meat and pouch water of undepurated and depurated mussels. Among these phyla, Cyanobacteria was more predominant on day 0 in mussel meat of undepurated and depurated mussels while Proteobacteria was predominant in commercially-depurated mussels. Synechococcus was apparently dominant on days 0-7 in the meat of undepurated mussels and days 0-10 in depurated mussels. Shewanella was dominant on day 0 in commercially-depurated mussels and dominant on day 15 in undepurated while Acidaminococcus was dominant in depurated mussels on day 15. Psychromonas was observed to be dominant in commercially-depurated mussels on day 7 and further shifted to Acinetobacter by day 10 and 15. In the pouch water, Acinetobacter was dominant throughout the storage days in undepurated mussels while Psychrobacter was predominant in both depurated and commercially-depurated mussels. This study demonstrated the impact of depuration on the microbiota and the spoilage mechanism of MA-packaged live mussels. Shewanella was easily removed through depuration. However, spoilage bacteria such as Acidaminococcus could not be easily removed although they are not important at the beginning but grew at the end. Pouch water contributed suitable biological medium for the growth of Acinetobacter and Psychrobacter and both enhanced the growth of spoilage bacteria such as Shewanella and Acidaminococcus.

Made available in DSpace on 2019-10-06T15:35:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 The use of organic residues in agriculture can contribute to the management of plant diseases and improvements in soil fertility. However, their effects on banana Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), are poorly understood. In this study, the biotic and abiotic effects on soil suppressiveness of banana Fusarium wilt were evaluated after incorporation of composted sewage sludge, biochar, shrimp peels and mussel shells into the soil. Residues were incorporated at rates of 0, 1, 2, 3, 4, and 5%, v:v in soil previously infested with Foc. Plantlets of banana cv. Maçã (AAB) were transplanted seven days after residue incorporation. Notable with respect to the other residues and concentrations studied, sewage sludge at 4% and 5% reduced plant disease (disease severity index and external severity) and increased plant growth. All concentrations of biochar and sewage sludge at 2% and 3% had intermediate effects. Disease severity and plant growth in plants grown in soil containing shrimp peels and mussel shells were similar to those of the untreated control. Negative correlations were observed between disease parameters and soil basal respiration, bacterial population, electrical conductivity, pH, V% (base saturation), CEC, P, K, Ca, Mg, Na, Zn, Mn and B. Universidade Estadual Paulista “Júlio de Mesquita Filho” UNESP/FCA Embrapa Meio Ambiente, CP 69 Universidade Estadual Paulista “Júlio de Mesquita Filho” UNESP/FCA

Sea surface salinity (SSS) is a key parameter to understand and predict many physical, chemical and biological processes in dynamic coastal environments. Yet, in many regions, instrumental measurements are spatially sparse and insufficiently long, hindering our ability to document changes, causes, and consequences of SSS across different time scales. Therefore, there is an need to develop a robust proxy to extend SSS records back in time. Here, we test whether SSS can be reconstructed reliably and quantitatively from shell oxygen isotopic ratios (δ18Oshell) of the mussel Mytilus galloprovincialis (Lamarck, 1819) in Otsuchi Bay, Northern Japan. δ18Oshell ratios vary spatially and temporally and exhibit strong linear correlations with both sea surface temperature (SST) and SSS measurements, indicating that the composite signal recorded by δ18Oshell measurably responds to variations in both parameters. By combining contemporaneous variations of SST and δ18Oshell, SSS records encoded into mussel shells are deconvolved that significantly correlate with in situ SSS values. To further validate the robustness of δ18Oshell as a quantitative SSS proxy, high-resolution and temporally aligned time-series of δ18Oshell-derived SSS are reconstructed that are highly synchronous with the instrumental records. In particular, two lowered SSS scenarios occur concomitantly with periods of the summer monsoon and typhoon events. δ18Oshell-derived SSS time-series are also comparable to those from numerical modeling. In conclusion, our findings demonstrate that mussel δ18Oshell signatures can be used as a useful tool to construct high-resolution records of SSS in the coastal regions.

The fan mussel, Pinna nobilis (Linnaeus 1758), is an endemic bivalve of the Mediterranean basin, protected by international legislation as an endangered species. In the early summer of 2018, a mass mortality event (MME) of P. nobilis was recorded in the Gulf of Taranto (Southern Italy, Ionian Sea). Moribund specimens of P. nobilis were collected by scuba divers and processed by bacteriological, parasitological, histopathological and molecular analyses to investigate the causes of this MME. Different developmental stages (i.e., plasmodia, spores and sporocysts) of a presumptive haplosporidian parasite were observed during the histological analysis in the epithelium and in the lumen of the digestive tubules, where mature spores occurred either free or in sporocysts. The spores presented an operculum and an ovoid shape measuring 4.4 µm (±0.232) in length and 3.6 µm (±0.233) in width. BLAST analysis of an 18SrRNA sequence revealed a high nucleotide similarity (99%) with the reference sequence of Haplosporidium pinnae available in GenBank database. Phylogenetic analysis clustered the sequence of the pathogen in a paraphyletic clade with the reference sequence of H. pinnae, excluding other haplosporidians (i.e., Bonamia and Minchinia genera). Based on data reported, H. pinnae was the causative agent of MME in the populations of P. nobilis sampled in the Ionian Sea, where the conservation of this endangered species is heavily threatened by such a protozoan infection. Further investigations should contribute to knowledge about the life cycle of H. pinnae in order to reduce spread of the pathogen and to mitigate the burden of the disease where P. nobilis is facing the risk of extinction.

This study investigates the immediate and mid-term effects of the biogeochemical variables input into the Reloncavi fjord (41°40′S; 72°23′O) as a result of the eruption of Calbuco volcano. Reloncavi is an estuarine system supporting one of the largest mussels farming production within Northern Chilean-Patagonia. Field-surveys were conducted immediately after the volcanic eruption (23–30 April 2015), one month (May 2015), and five months posterior to the event (September 2015). Water samples were collected from three stations along the fjord to determine greenhouse gases [GHG: methane (CH4), nitrous oxide (N2O)], nutrients [NO3−, NO2−, PO43−, Si(OH)4, sulphate (SO42−)], and carbonate systems parameters [total pH (pHT), temperature, salinity, dissolved oxygen (O2), and total alkalinity (AT)]. Additionally, the impact of physicochemical changes in the water column on juveniles of the produced Chilean blue mussel, Mytilus chilensis, was also studied. Following the eruption, a large phytoplankton bloom led to an increase in pHT, due to the uptake of dissolved-inorganic carbon in photic waters, potentially associated with the runoff of continental soil covered in volcanic ash. Indeed, high surface SO42− and GHG were observed to be associated with river discharges. No direct evidence of the eruption was observed within the carbonate system. Notwithstanding, a vertical pattern was observed, with an undersaturation of aragonite (ΩAr 10 m), and saturated values in subsurface waters (3 to 7 m). Simultaneously, juvenile mussel shells showed maximized length and weight at 4 m depth. Results suggest a localized impact of the volcanic eruption on surface GHG, nutrients and short-term effects on the carbonate system. Optimal conditions for mussel calcification were identified within a subsurface refuge in the fjord. These specific attributes can be integrated into adaptation strategies by the mussel aquaculture industry to confront ocean acidification and changing runoff conditions.

Geographical traceability of marine bivalves is critical to guarantee their quality and safeguard the interest of both consumers and producers. The neodymium isotopic ratio (143Nd/144Nd) of the coastal water mainly reflects the geology of its neighboring watershed, displaying the distinct and systematic variability at high level of geographical detail and thereby shedding light on its potential as a geochemical tracer. For the first time, the present study investigated the utility and robustness of 143Nd/144Nd archived in mytilid mussel shells for geographical traceability purposes. The reproducibility of 143Nd/144Nd ratios maintained in mussels shells from the same cohort demonstrates that the Nd isotopic ratio meets the major requirement for an ideal geochemical tracer, i.e., the biologically induced variation should be rather minimal. The distribution and variability of mussel shell 143Nd/144Nd patterns were subsequently mapped along the Japanese and Chinese coastal waters. Neodymium isotopes of mussel shells record 143Nd/144Nd variations among local regions and between the two countries, which are rather compatible with the ages and lithology of the continental bedrocks. These findings highlight the great potential of 143Nd/144Nd for tracing the geographical origin of marine bivalves.

In coastal habitats, physical disturbances of benthic organisms can be caused by natural events like wave-born objects and human activity like trampling, and these disturbances can be sub-lethal (e.g., resulting in the organism's displacement). We know little of how sessile organisms respond to physical disturbances such as displacements. Using Mytilaster minimus, a mussel that is native to the Mediterranean Sea, we tested how byssus production and oxygen uptake rates changed in response to different frequencies of disturbance events (10-60 events h-1). Mussels increased oxygen uptake rates but not byssus production with increasing disturbance frequencies (50-60 events h-1). Our results show that sub-lethal, physical disturbances can cause increased physiological rates in mussels if disturbances repeat rapidly. Therefore, sub-lethal, physical disturbances can have negative consequences for benthic organisms even if they do not cause immediate damage or mortality.