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Background: Amidst the escalating loss of global biodiversity, freshwater mussels (family Unionidae) have become one of the most imperiled animal groups. Acquiring more biological and phylogenetic information on understudied taxa constitutes a pivotal aspect of conservation biology. Consequently, a comprehensive examination was conducted on Koreosolenaia, Parvasolenaia, and Sinosolenaia from China encompassing morphology, anatomy, distribution, and molecular systematics to provide theoretical support for future species endangerment assessments and biodiversity conservation. Results: The shell characteristics of Koreosolenaia, Parvasolenaia, and Sinosolenaia were clearly distinct, and the soft-body morphology could also be easily distinguished from each other. The papillae of the incurrent aperture of Sinosolenaia iridinea, Sinosolenaia recognita, and Sinosolenaia oleivora, which were previously described as difficult, exhibited significant variations that could be utilized for species diagnosis. Furthermore, both incurrent and excurrent apertures of the Sinosolenaia species had small cysts on their dorsal surfaces which may be unique to this particular group. Comparative analysis of six mitochondrial genomes (Parvasolenaia rivularis, Koreosolenaia sitgyensis, Sinosolenaia iridinea, Sinosolenaia recognita, Sinosolenaia carinata, and Sinosolenaia oleivora) revealed a completely consistent gene arrangement pattern. Additionally, there was a high consistency in nucleotide base content and skewness, amino acid usage, and relative synonymous codon usage among the six complete mitochondrial genomes. Mitochondrial phylogenomics of these genomes with additional taxa within Gonideinae robustly supported the generic relationships as follows: (Inversidens + ((Microcondylaea + Sinosolenaia) + (Parvasolenaia + (Koreosolenaia + (Ptychorhynchus + (Postolata + Cosmopseudodon)))))). Conclusions: The present study provided significant data on the shell morphology and soft-body anatomy of Koreosolenaia, Parvasolenaia, and Sinosolenaia, thereby clarifying the diagnostic characteristics for these challenging taxa. Additionally, we established a robust phylogenetic framework at both the generic and species levels based on mitochondrial genomics. [ABSTRACT FROM AUTHOR]

The shells of freshwater mussels, commonly found at archaeological sites associated with the Kodjadermen-Gumelnița-Karanovo VI human groups (5th millennium BCE, Romania and Bulgaria), were a significant dietary component for this population. The organic matrix of these ancient shells is often well-preserved and can be analysed using stable isotopes. This study establishes the empirical relationship between the isotopic composition of the acid-insoluble shell organic matrix (AIM) and the soft tissues of modern Unio tumidus. A quality criterion for AIM (C:N ratio 3.6 (3.3–<3.8)) was defined, and isotopic offsets (Δ15NAIM-defatted body = +0.95‰, Δ13CAIM-defatted body = +0.93‰ for soft tissues; Δ15NAIM-muscle = +1.7‰, Δ13CAIM-muscle = +0.3‰ for the adductor muscle) were determined. Our data suggest that the Gumelnița mussels were omnivorous, with a similar trophic level to carp and pond turtles, sourced from diverse water bodies (rivers, lakes ...) based on δ13C values. [ABSTRACT FROM AUTHOR]

Freshwater mussels of the tribe Gonideini (Bivalvia: Unionidae: Gonideinae) constitute one of the most taxonomically diverse groups and serve as keystone species in riverine and lacustrine ecosystems across East Asia. A new genus and species of Gonideini (Bivalvia: Unionidae) is described from Jiangxi, China, as Pseudopostolata angula gen. et sp. nov. based on an integrative analysis of shell morphology and molecular data. The validity of the new genus and species is supported by distinct conchological features: a short, rounded anterior; a long, wide posterior; a slightly downward-curved dorsal margin; and a distinctly obtuse angle at the center of the posterior margin. The multi-locus (COI + 16S rRNA + 28S rRNA) phylogeny showed that the species formed a monophyletic group in the tribe Gonideini of the subfamily Gonideinae. Pseudopostolata angula gen. et sp. nov. is identified as the sister group to a clade comprising the genera Postolata, Cosmopseudodon, Obovalis, Ptychorhynchus, Parvasolenaia, and Koreosolenaia. We emphasize the significant morphological convergence in freshwater mussels, particularly within Gonideini, highlighting the necessity of an integrated taxonomic approach for accurate generic classification of this group. [ABSTRACT FROM AUTHOR]

Two new genera and three new species of freshwater mussels in the tribe Pseudodontini (Bivalvia, Unionidae) are described from the Mekong Basin in Thailand based on an integrative taxonomic study involving morphology and multi-locus phylogenetic analyses (mitochondrial COI and 16S, and nuclear 28S genes). The monotypic genus, Lannanaia kokensis gen. et sp. nov., presents unique features of being rather compressed, sub-trigonal in outline with short and high shell, and with a distinct posterior wing. Another new genus, Isannaia gen. nov., is characterized by having a thin and moderately inflated shell, with rhomboidal to ovate outline. It includes two lineages that are genetically separated by 3.54% uncorrected COI p-distance, and are herein described as I. fortunata sp. nov. and I. occultata sp. nov. Phylogenetic analyses further revealed that these two new genera were nested within a clade of subtribe Pseudodontina, and with pairwise uncorrected COI p-distance to other genera ranging from 11.42 to 15.66%. Based on the present data, Lannanaia gen. nov. is known only from the Kok River in the north of Thailand, whereas the two species of Isannaia gen. nov. are restricted to tributaries of the Mekong River in the northeast of Thailand. The discovery of rare and probably endemic freshwater mussels in the Mekong Basin thus again highlights the importance of this region among freshwater biodiversity hotspots of the world. [ABSTRACT FROM AUTHOR]

The Pearl River Basin, China's second-largest freshwater basin, hosts a significant diversity of species and a highly endemic freshwater mussel fauna. In this study, a new species from the Liuxi River in Guangzhou, Guangdong, China, Pletholophus guangzhouensis sp. nov., is described based on morphological diagnostic features and molecular phylogenetics. The glochidia shells of the new species are subtriangular, medium-sized, and have a styliform hook on the ventral angle of each valve. Phylogenetic analyses based on the COI and 28S rRNA gene fragments indicated that Pletholophus guangzhouensis sp. nov. is the sister to Pletholophus tenuis + Pletholophus reinianus. The pairwise uncorrected COI p-distance analysis demonstrated genetic distances ranging from 5.27% (between P. guangzhouensis sp. nov. and P. tenuis) to 11.06% (between P. guangzhouensis sp. nov. and P. honglinhensis). Our findings suggest a significant underestimation of the diversity of freshwater mussel species in Guangdong. Further field collections and systematic studies are necessary to fully explore the biodiversity of this region. Furthermore, integrative classification methods and genetic research are essential for informing the development of effective conservation strategies. [ABSTRACT FROM AUTHOR]

Asexual taxa are often considered as rare and vowed to long-term extinction, notably because of their reduced ability for rapid genetic changes and potential adaptation. The rate at which they derive from sexual ancestors and their developmental mode however influence genetic variation in asexual populations. Understanding the transition from sexuality to asexuality is therefore important to infer the evolutionary outcome of asexual taxa. The present work explored the transition from sexuality to androgenesis, a reproductive mode in which the males use female resources to clone themselves, in the freshwater Corbicula clams. Since androgenetic lineages are distinguishable from sexual clams by the production of unreduced sperm, this study investigated the cytological mechanisms underlying spermatogenesis in Corbicula by following the DNA content variation of male germ cells. The widespread androgenetic C. sp. form A/R lineage was compared to the sexual species C. japonica and C. sandai. While in C. japonica, the last stages of spermatogenesis are reduced through a canonical meiosis process, no reduced or duplicated stages were observed in C. sp. form A/R, suggesting a meiosis modification in this lineage. However, 45% of C. sandai spermatozoa were unreduced. The production of unreduced sperm may condition or provide the potential for the emergence of androgenesis in this sexual species. Being closely related to androgenetic lineages and found in sympatry with them in Lake Biwa (Japan), C. sandai might be an origin of androgenetic lineage emergence, or even an origin of the androgenetic reproductive mode in Corbicula. [ABSTRACT FROM AUTHOR]

Niche partitioning promotes species coexistence. Yet, it remains unclear how phylogeny and morphology influence the trophic niches of closely related aquatic species with shared feeding modes. Freshwater mussels (Family: Unionidae) are a group of filter‐feeding bivalves that are ideal for investigating mechanisms of niche partitioning. Particle size selection and patterns of ingestion are controlled by gill latero‐frontal cirri density (CD) and the number of cilia per cirrus (CC). We investigated trophic assimilation and niche area using stable isotope signatures (훿13C and 훿15N) and gill morphology with scanning‐electron microscopy for a diverse mussel assemblage from the Sipsey River, Alabama, USA. We predicted that (1) trophic niches and gill morphology would differ within and among species across sites; (2) co‐occurring species would partition food resources; (3) greater phylogenetic distances among species would result in increased trophic dissimilarity; (4) more CC and higher CD would result in a narrower trophic niche area, or more constrained range of food items assimilated. We found that (1) species identity and site influenced gill morphology and stable isotope signatures but that the trophic niche area of a species was only affected by species identity; (2) the average proportion of niche area overlap between co‐occurring species was low across sites (0.04 to 0.18); (3) trophic dissimilarity among species increased with phylogenetic distance; (4) CD but not the number of CC negatively related to trophic niche area. Our results indicate that gill morphology and evolutionary history are likely key factors governing the trophic niches of mussels. In addition, intraspecific variation in gill morphology across sites may either reflect a phenotypic response to differences in local resource availability or suggest that other mechanisms shape particle selection. Examining the interplay among the trophic niche, phylogeny, and morphology among functionally similar species further informs our understanding of the mechanisms facilitating their coexistence. [ABSTRACT FROM AUTHOR]

The presence of sub-micron-sized plastics in the environment has been increasing, with the possible risks of these particles remaining relatively unknown. In order to assess the toxicity of these particles, 100 nm diameter green fluorescent nano-polystyrene spheres (NPS) (20–60 mg/L) were exposed to zebra mussels (Dreissena polymorpha) to investigate the mortality, clearance rate and stress-related biomarker responses. D. polymorpha were collected and analysed with standard OECD toxicological tests and biomarker analysis to detect both physical and biochemical responses after exposure to NPS. The toxicity of the NPS to D. polymorpha was low, with 60 mg/L NPS causing a mortality rate of 11.1% at 96 h which was statistically significant compared to the 4.2% control. No statistical change could be found for the condition factor (kc) of D. polymorpha after NPS exposure. Clearance rates in D. polymorpha using R. subcapitata algae showed NPS-exposed mussels had a reduction of filtering efficiency of up to 30.5%. Bioassay testing shows a mixed but undeniably negative response from the D. polymorpha to the NPS, notably a significant rise in DNA Strand Breaks (DSB) and Metallothionein (MT) responses for high NPS concentrations. Additionally, Lipid Peroxidation (LPO) and Ferric Reducing Antioxidant Power (FRAP) assay tests showed a significant increase in response from the higher (>40 mg/L) concentrations of NPS exposure. Although Glutathione S-Transferase (GST) assay showed no statistical change from the control for all NPS-exposed samples, an increase of 20% had occurred for 60 mg/L NPS. Overall, a minimal toxic response from D. polymorpha to the NPS exposure below 40 mg/L was seen. After 40 mg/L NPS, mussels presented more acute toxicity in terms of mortality, along with reduced algal clearance rates and anincrease in biomarker response. This study revealed a clear induction of oxidative stress and DSB in the digestive gland of zebra mussels following exposure to nano-polystyrene. While these findings provide valuable insights into the potential harmful effects of nanoplastics in freshwater bivalves, further studies are necessary to help understand the level of threat plastic pollution may pose to the health of freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Background Amidst the escalating loss of global biodiversity, freshwater mussels (family Unionidae) have become one of the most imperiled animal groups. Acquiring more biological and phylogenetic information on understudied taxa constitutes a pivotal aspect of conservation biology. Consequently, a comprehensive examination was conducted on Koreosolenaia, Parvasolenaia, and Sinosolenaia from China encompassing morphology, anatomy, distribution, and molecular systematics to provide theoretical support for future species endangerment assessments and biodiversity conservation. Results The shell characteristics of Koreosolenaia, Parvasolenaia, and Sinosolenaia were clearly distinct, and the soft-body morphology could also be easily distinguished from each other. The papillae of the incurrent aperture of Sinosolenaia iridinea, Sinosolenaia recognita, and Sinosolenaia oleivora, which were previously described as difficult, exhibited significant variations that could be utilized for species diagnosis. Furthermore, both incurrent and excurrent apertures of the Sinosolenaia species had small cysts on their dorsal surfaces which may be unique to this particular group. Comparative analysis of six mitochondrial genomes (Parvasolenaia rivularis, Koreosolenaia sitgyensis, Sinosolenaia iridinea, Sinosolenaia recognita, Sinosolenaia carinata, and Sinosolenaia oleivora) revealed a completely consistent gene arrangement pattern. Additionally, there was a high consistency in nucleotide base content and skewness, amino acid usage, and relative synonymous codon usage among the six complete mitochondrial genomes. Mitochondrial phylogenomics of these genomes with additional taxa within Gonideinae robustly supported the generic relationships as follows: (Inversidens + ((Microcondylaea + Sinosolenaia) + (Parvasolenaia + (Koreosolenaia + (Ptychorhynchus + (Postolata + Cosmopseudodon)))))). Conclusions The present study provided significant data on the shell morphology and soft-body anatomy of Koreosolenaia, Parvasolenaia, and Sinosolenaia, thereby clarifying the diagnostic characteristics for these challenging taxa. Additionally, we established a robust phylogenetic framework at both the generic and species levels based on mitochondrial genomics.

Abstract Background Freshwater mussels are important keystone and indicator species of aquatic ecosystems. Recent advances in sensor technology facilitate applications to individually track mussels and to record and monitor their behavior and physiology. These approaches require the attachment of sensor devices as “backpacks” to the outer shell surface. The interpretation of such data makes it necessary to understand the influence of these attachments on the horizontal and vertical movement behaviors of freshwater mussels. Over a series of mesocosm experiments, this study systematically investigated the effects of three size- and wiring-specific variants of artificially attached backpacks on the horizontal and vertical movement behavior of Anodonta anatina. Results Across all experiments, equipping mussels with backpacks did not result in a significant influence on horizontal movement for any of the backpack variants. In contrast to this finding, the big backpacks with a high ratio between backpack volume and mussel length resulted in a significantly negative effect on vertical movement, indicating a potential for adverse effects of such devices on mussels, especially in natural settings. Conclusions The findings of this study show that assessing the effects of attached devices on mussels requires a species-specific evaluation of potential impacts on the endpoints of interest. Especially for vertical movement patterns, selection of the smallest available devices appears mandatory.

The Host-Habitat Continuum Concept (HHCC) predicts changes in the proportions of freshwater mussels with different life-history strategies (i.e., equilibrium, periodic, opportunistic) along stream gradients and between habitat types. We analyzed mussel assemblages from a large, diverse geographic area to test predictions of the HHCC and to assess if species richness, abundance, and host strategy patterns change predictably among different habitats (lakes, reservoirs, and streams) and stream sizes. Species richness and abundance were low in lakes, reservoirs, and small streams and increased with stream size. Mussels use various strategies to attract fish hosts and the proportion of mussels that release conglutinates (i.e., packets of glochida) increased with stream size and the proportion that use lures decreased. Our results supported predictions of the HHCC: greater proportions of opportunistic or periodic strategists in lakes, reservoirs, and small streams and a shift to equilibrium strategists in larger streams. Patterns differed slightly in lakes and reservoirs with a higher proportion of periodic strategists than expected. Not all watersheds followed predictions of the HHCC likely due to the effects of biogeography and anthropogenic impacts. These life history strategy patterns can be used to test the expected composition of mussel communities and to detect possible anthropogenic impacts. [ABSTRACT FROM AUTHOR]

(1) Mercury (Hg) is a persistent, ubiquitous contaminant that readily biomagnifies into higher trophic level species in aquatic environments across the globe. It is crucial to understand the movement of environmentally relevant concentrations of Hg in impacted freshwater streams to minimize risks to ecological and human health. (2) The bioconcentration kinetics of aqueous Hg exposure (20, 100, and 200 ng/L) in the invasive Asian Clam, Corbicula fluminea, were measured. A toxicokinetic model, the first parameterized for Hg accumulation in freshwater clams, was developed to estimate uptake and efflux parameters and compared to previous parameter values estimated for other mollusk species. (3) Results demonstrated that even at low Hg concentrations, Corbicula record signals of contamination through bioconcentration, and both direct measurement and toxicokinetic models demonstrate large Hg bioconcentration factors (as high as 1.34 × 105 mL/g dry tissue), similar to partitioning coefficients seen in engineered Hg sorbents. (4) Our study found that Corbicula accumulated Hg at aqueous concentrations relevant to impacted streams, but well below regulatory drinking water limits, demonstrating their utility as a sensitive sentinel species and potential bioremediator. [ABSTRACT FROM AUTHOR]

Climate change poses a significant threat to freshwater ecosystems by causing increases of average water temperatures, and more frequent and extreme heating events. Freshwater mussels are declining globally, and the distribution of the freshwater pearl mussel (Margeritifera margeritifera) has decreased dramatically over the past century. Even though it is likely that climate change is contributing to the decline of the species, little is known about the specific mechanisms involved. Here, we test how short episodes of water temperatures above the known thermotolerance range affect the survival and growth of the early post parasitic juvenile phase of freshwater pearl mussels. We also test if previous experience with elevated water temperatures can modify survival and growth responses to subsequent high‐temperatures exposure. Mortality was very low in all treatments (< 5%) and not affected by the temperature treatments, while growth rate was positively affected by temperature. Our results suggest that juvenile mussels can survive short periods of heat stress when other environmental conditions are favourable. Future studies should therefore address how heat stress affects survival in combination with other stressors, such as reduced availability of dissolved oxygen. [ABSTRACT FROM AUTHOR]

Mass die-offs, reduced species richness and local extinctions of freshwater mussels have resulted from river drying events, which often co-occur with high ambient temperatures. These events are predicted to increase in frequency and severity under the influence of climate change. We aimed to identify the desiccation tolerance of two freshwater mussel species (the river mussel Alathyria jacksoni and the floodplain mussel Velesunio ambiguus) across a range of temperatures by simulating river drying events in laboratory conditions. Freshwater mussels were buried in sediment heated to 29, 32, 35, 38 and 41°C. Lethal times and lethal temperatures at which 50% mortality occurred were used to infer species-specific tolerances. The lethal time for 50% of mussels to reach mortality at 29°C was shorter for A. jacksoni (14 days) than V. ambiguus (58 days) but did not differ markedly at higher temperatures. Lethal temperatures were also similar between species over short durations (e.g. 39–40°C at 1 day). Our results suggest that the difference in desiccation tolerance between species diminishes toward their upper thermal limit. Management interventions aimed at reducing sediment temperatures, such as providing shade via riparian vegetation and wetting from environmental flows, could help alleviate the impact of drying events and climate change on both freshwater mussel species. [ABSTRACT FROM AUTHOR]

In this study, the activity of oxidative stress parameters superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), and glutathione S-transferase (GST), as well as the concentrations of vitamin E (Vit E) and SH groups in the digestive glands and gills of freshwater mussels Unio pictorum and Sinanodonta woodiana from the Sava River in Serbia were investigated. These parameters were determined in native and invasive mussels under the same environmental conditions. The activities of GSH-Px and GR and the concentration of Vit E were significantly higher in the digestive glands of the autochthonous species U. pictorum than in the invasive species S. woodiana, while the CAT activity and the concentration of SH groups were lower. In the gills of U. pictorum, GSH-Px activity and Vit E concentration were significantly higher, while CAT, GST, and SH groups were lower. Principal component analysis (PCA) showed that oxidative stress parameters were strictly tissue- and species-specific. In addition, integrated biomarker response (IBR) showed a combined response of enzymatic and non-enzymatic oxidative stress parameters depending on the tissue or species studied, indicating different metabolic activities and behaviors of an autochthonous versus an introduced bivalve species. [ABSTRACT FROM AUTHOR]

Protein-based emulsion gels are an ideal delivery system due to their unique structure, remarkable encapsulation efficiency, and tunable digestive behavior. Freshwater mussel (Solenaia oleivora) protein isolate (SoPI), an emerging sustainable protein with high nutritional value, possesses unique value in the development of functional foods. Herein, composite emulsion gels were fabricated with SoPI and κ-carrageenan (κ-CG) for the delivery of curcumin. SoPI/κ-CG stabilized emulsions possessed a high encapsulation efficiency of curcumin with a value of around 95%. The addition of κ-CG above 0.50% facilitated the emulsion gel formation and significantly improved the gel strength with 1326 g. Furthermore, the storage and digestive stability of curcumin were significantly improved as the κ-CG concentration increased. At 1.50% κ-CG, around 80% and 90% curcumin remained after 21-day storage at 45 °C and the 6 h in vitro gastrointestinal digestion, respectively. The addition of 0.50% κ-CG obtained the highest bioaccessibility of curcumin (~60%). This study illustrated the potential of SoPI emulsion gels as a carrier for stabilizing and delivering hydrophobic polyphenols. [ABSTRACT FROM AUTHOR]

The round goby (Neogobius melanostomus) is a well-known invasive fish. Knowledge of its feeding habits and means of food processing is key in understanding its impact on aquatic food webs. The present study assessed the gut evacuation rate of round gobies feeding on three different types of prey occurring naturally in the diet of this species (small native freshwater clams, an invasive amphipod and chironomid larvae), at two different temperatures (14 and 20 °C) and under different food availability scenarios (continuous and non-continuous feeding). Gut evacuation rates varied significantly between the prey availability scenarios and, specifically, round gobies processed prey significantly faster in the continuous feeding mode when food was regularly available than when fed only once. The highest evacuation rates were detected for individuals fed with clams, in which complete gut clearance was observed within 16 h, compared to within 24 h and 36 h for chironomid larvae and amphipods, respectively. Our study shows that round gobies evacuate chironomid and mollusc prey most rapidly, which suggests that potentially the highest predatory pressure will be exerted on these prey types, assuming that all three prey species are locally present. The slower processing and digestion of amphipods may be due to their bulkier shape, which makes them more difficult to swallow. The relatively high evacuation efficiency of the round goby observed in the continuous feeding mode suggests overall increased pressure on food resources, thereby potentially reducing availability for other consumers and accelerating resource depletion, mainly driven by the high local densities of the round goby populations. [ABSTRACT FROM AUTHOR]

Ecosystem engineers alter habitat and resource availability within ecosystems, but the magnitude of these effects depends on abiotic context and spatial scale. We examined how the effects of freshwater mussels, an ecosystem engineer, changed with spatial scale. We combined a field enclosure experiment and comparative field study to evaluate associations among mussels and macroinvertebrate communities across three spatial scales: mussel individuals (~ 0.01 m2), patches of mussels (0.25 m2), and large aggregations of many mussel patches (mussel beds, ~ 1000 m2). We used canonical correspondence analysis and variation partitioning to evaluate how mussel abundance, food availability, substrate heterogeneity, and flow influenced macroinvertebrate communities. We found that mussels' influence on macroinvertebrate communities differed among spatial scales. At the smallest scale, macroinvertebrate density increased on the shells of live mussels, likely due to mussel influences on food availability to grazers. At the patch scale, we found no mussel effects, likely because they were overridden by a flood event. At the mussel bed scale, macroinvertebrate communities were primarily controlled by flow and secondarily by food availability. As such, the continued loss of freshwater mussels means the loss of habitat creation and food provisioning for other aquatic groups, and alteration of facilitation landscapes within streams. [ABSTRACT FROM AUTHOR]

Global increase in aquaculture production has created a need to reduce its environmental impacts. Nutrients could be recycled especially at land-based recirculating aquaculture systems (RAS) by cultivating green microalgae in aquaculture effluent. However, microalgae are difficult to harvest. As a multi-trophic solution, mussels could be used in harvesting microalgae. We tested three European freshwater mussels (duck mussel Anodonta anatina, swan mussel A. cygnea, and swollen river mussel Unio tumidus) for filtering two common green microalgae (Monoraphidium griffithii and Selenastrum sp.) grown in RAS effluent. Mussels decreased microalgal concentrations in the tanks 42–83% over three consecutive trials. Algal concentrations at the end of each trial were lowest for both microalgae in tanks containing Anodonta mussels. Clearance rates were higher for Anodonta mussels than for U. tumidus. Mussels biodeposited more microalgae to tank bottoms when M. griffithii was filtered. Ammonium concentration decreased or did not change in tanks with M. griffithii, but increased in tanks containing Selenastrum sp. These results suggest that of the tested species Anodonta mussels and M. griffithii show best potential for RAS effluent bioremediation application. We conclude that a co-culture of microalgae and unionid mussels could be used for recycling nutrients in aquaculture. [ABSTRACT FROM AUTHOR]

Unionid mussels deposit growth rings (annuli) within the shell, which can be used to estimate age and growth. Thin-sectioning is a common technique for counting annuli, wherein a cross-section of a shell valve is taken and evaluated by multiple readers. Correctly identifying annuli can be challenging because ambiguous annuli can bias growth estimates. Staining with calcein, a fluorescent chemical, is a technique that has been used with marine and freshwater species to improve accuracy of growth estimates. This method chelates calcium, causing a permanent mark that fluoresces under ultraviolet light. Calcein has seen limited testing on unionid mussels so it remains unclear if this method has adverse effects on survival and growth. We evaluated calcein against 2 concentrations (125 mg L−1 and 250 mg L−1) at 2 exposure times (12 and 24 h) on Cyclonaias pustulosa, a common North American unionid. Survivorship remained above 80% 6 months post-immersion. Mark quality and retention for 250 mg L−1 were high for both 12- and 24-h immersions, although historical annuli were not highlighted. These findings corroborate studies indicating calcein immersion is generally safe and effective in juveniles and adults and suggest it may be useful in validating new growth. [ABSTRACT FROM AUTHOR]

Water quality in land-based fish production can be controlled through either instantaneous water exchange or costly wastewater treatment followed by recirculation. Agricultural-aquaculture integration is an excellent alternative technique for reducing nutrient discharge levels, boosting profitability, and converting fish culture wastewater into valuable products. The current study employed a solar energy system to power two separate IMTA-aquaponics systems (Nutrient Film Technique, NFT, and Floating Raft Systems, FRS) for the cultivation of Nile tilapia, African catfish, thin-lipped grey mullet, freshwater crayfish, freshwater mussels, and a variety of vegetables. Tilapia and catfish were fed exclusively on diets under the IMTA system. All wastewater from tilapia and catfish ponds, both dissolved and solid, flows sequentially to ponds containing other cultivated species. The water then flows through the IMTA system's terminal point to the NFT and FRS systems before returning to the tilapia and catfish ponds, allowing complete control of the nutrient flow throughout this entire circular system. Two 147-day production cycles were concluded. The results from the second production cycle are reported. Total biomass gain for aquatic species in the IMTA system was 736.46 kg, compared to 145.49 kg in the tilapia and 271.01 kg in the catfish monoculture systems. The current IMTA system had a cumulative feed conversion ratio (FCR) of 0.90, while the FCRs for tilapia and catfish were 1.28 and 1.42, respectively. Nile tilapia and catfish consumed 571.90 kg of feed containing 25.70 kg of nitrogen (N) and 9.70 kg of phosphorus (P), reflecting, and gaining 11.41 and 3.93 kg of dietary N and P, representing 44.40 and 40.46% dietary N and P retention, respectively. In the IMTA system, the addition of mullet and prawn as detrivores aquatic animals improves dietary N and P utilization efficiency to 59.06 and 51.19%, respectively, while the addition of mussels as herbivore animals improves dietary N and P utilization efficiency to 65.61 and 54.67%, respectively. Finally, using FRS and NFT as hydroponic systems increased dietary N and P efficiency to 83.51% N and 96.82% P, respectively. This study shows that the IMTA-Aquaponic system, as a bio-integrated food production system, can convert the majority of fish-fed residues into valuable products suitable for desert, rural, and urban areas in impoverished and developing countries. [ABSTRACT FROM AUTHOR]

In this study, we present a new species of freshwater mussel in the genus PostolataDai et al., 2023, from Guangxi Province, China, by integrating morphological, anatomical, and molecular data. Postolata longjiangensis Liu & Wu, sp. nov. is distinguished from its congener (i.e., Postolata guangxiensis) by its shell shape, beak position, surface sculpture, nacre color, and hinge structure. Molecular species delimitation results based on the mitochondrial COI gene support the separation of Postolata longjiangensis Liu & Wu, sp. nov. from its congener. The multi-locus (COI + 16S rRNA + 28S rRNA) phylogeny reveals that this species forms the sister lineage to Postolata guangxiensis in the tribe Gonideini. [ABSTRACT FROM AUTHOR]

Simple Summary: This study explores how the autumn-spawning bitterling, Acheilognathus rhombeus, reproduces and develops within its mussel host. The research highlights how these fish lay their eggs inside mussels, which then serve as a safe environment for the eggs to develop over winter. A critical phase, called diapause, allows the embryos to pause their development for about seven months, ensuring they survive the cold winter months. Once the temperature rises above 10 °C, development resumes. During this time, tiny structures on the embryos called minute tubercles help anchor them within the mussel, preventing them from being expelled prematurely. These findings provide valuable insights into the complex relationship between the bitterlings and their mussel hosts, revealing important evolutionary adaptations that aid in the reproductive success and survival of these fish. We investigated the reproductive strategies and embryonic development of Acheilognathus rhombeus (a bitterling species that spawns in autumn) within its freshwater mussel host in the Bongseo Stream, South Korea. By focusing on survival mechanisms during critical stages of embryonic development, the selective use of mussel gill demibranchs by the bitterlings and associated adaptive traits were observed over 1 year. A significant diapause phase occurs at developmental stage D, which lasts for approximately 7 months, allowing embryos to survive winter. Development resumes when the temperature exceeds 10 °C. Minute tubercles on the embryos (crucial for anchoring within the host gill demibranchs and preventing premature ejection) exhibit the largest height during diapause, and the height decreases when developmental stage E is reached, when growth resumes. Acheilognathus rhombeus embryos were observed in 30.5% of the mussels, mostly within the inner gills, thereby maximizing spatial use and oxygen access to enhance survival. These results highlight the intricate relationship between A. rhombeus and its mussel hosts, demonstrating the evolutionary adaptations that enhance reproductive success and survival. This study provides valuable insights into the ecological dynamics and conservation requirements of such symbiotic relationships. [ABSTRACT FROM AUTHOR]

Simple Summary: Freshwater mussels create habitat, filter water, and enhance food webs, but they are also among the world's most imperiled taxa. Conservation efforts largely rely on captive propagation in which mussels are grown in protected aquaculture environments (hatcheries) for later release. Recent evidence has highlighted the importance of pathogens in population losses of freshwater mussels. In response to ongoing mass mortality events of freshwater mussels in the Upper Tennessee River Basin in Virginia and Tennessee, USA, we conducted a multi-year study to document viruses across multiple restoration sites and compare them to viruses in mussels from the hatchery. Viral communities changed greatly after mussels were released. Of the 681 viruses of the 27 families we documented, only 20 viruses were found exclusively in hatchery mussels, compared to 451 viruses found only in mussels stocked to the wild. After release, mussels rapidly acquired new viruses, and the number of viruses increased steadily over time. These findings have implications for how mussel introduction programs might be managed for greater success, for example, by incorporating acclimatization periods prior to full release. Freshwater mussels (order: Unionida) are highly imperiled globally and are increasingly the focus of captive propagation efforts to protect and restore wild populations. The Upper Tennessee River Basin (UTRB) in Virginia is a freshwater biodiversity hotspot hosting at least 45 of North America's ~300 species of freshwater mussels, including 21 threatened and endangered species listed under the U.S. Endangered Species Act. Recent studies have documented that viruses and other microbes have contributed to freshwater mussel population declines in the UTRB. We conducted a multi-year longitudinal study of captive-reared hatchery mussels released to restoration sites throughout the UTRB to evaluate their viromes and compare them to captive hatchery environments. We documented 681 viruses from 27 families. The hatchery mussels had significantly less viruses than those deployed to wild sites, with only 20 viruses unique to the hatchery mussels. After the hatchery mussels were released into the wild, their number of viruses initially spiked and then increased steadily over time, with 451 viruses in total unique to the mussels in the wild. We found Clinch densovirus 1 (CDNV-1), a virus previously associated with mass mortality events in the Clinch River, in all samples, but the wild site mussels consistently had significantly higher CDNV-1 levels than those held in the hatchery. Our data document substantial differences between the viruses in the mussels in the hatchery and wild environments and rapid virome shifts after the mussels are released to the wild sites. These findings indicate that mussel release programs might benefit from acclimatization periods or other measures to mitigate the potential negative effects of rapid exposure to infectious agents found in natural environments. [ABSTRACT FROM AUTHOR]

Freshwater mussels preserve valuable information about hydrology, climate, and population dynamics, but developing seasonal chronologies can be problematic. Using clumped isotope thermometry, we produced high-resolution reconstructions of modern and historic (~ 1900) temperatures and δ18Owater from mussel shells collected from an impounded river, the Brazos in Texas, before and after damming. We also performed high-resolution growth band analyses to investigate relationships between mussel growth rate, rainfall, and seasonal temperature. Reconstructed δ18Owater and temperature vary little between the modern (3R5) and historic shell (H3R). However, a positive relationship between reconstructed δ18Owater and growth rate in H3R indicates that aside from diminished growth in winter, precipitation and flow rate are the strongest controls on mussel growth in both modern and pre-dam times. Overall, our results demonstrate (1) the impact, both positive and negative, of environmental factors such as flow alteration and temperature on mussel growth and (2) the potential for clumped isotopes in freshwater mussels as a paleohydrology and paleoclimate proxies in terrestrial environments. [ABSTRACT FROM AUTHOR]

Microeukaryotes are a diverse and often overlooked group of microbes that are important in food webs and other ecological linkages. Little is known about microeukaryotes associated with aquatic invertebrates, although filter feeders such as mussels are likely to take in and potentially retain microeukaryotes in their gut while feeding. Microeukaryotes such as apicomplexans have been reported in marine mussel species, but no studies have examined the presence of these microorganisms in freshwater mussels or how they relate to mussel host species or environmental conditions. In this study, microbial community DNA was extracted from the gut tissue of over 300 freshwater mussels, representing 22 species collected from rivers in the southeastern USA. Microeukaryote DNA was detected using PCR amplification, followed by the sequencing of positive amplicons. Microeukaryotes were found in 167 individual mussels (53%) of those tested. Amplicons included dinoflagellates/algae that differed between mussel species and are likely food sources that were distinct from those found in water and sediment samples analyzed concurrently. A total of 5% of the positive amplicons were non-photosynthetic alveolates that could represent parasitic microeukaryotes. Understanding the distribution of microeukaryotes in the freshwater mussel gut microbiome could further our understanding of the ongoing decline of mussel populations. [ABSTRACT FROM AUTHOR]

Freshwater mussels are integral components of riverine ecosystems, influencing water quality, nutrient cycling, and habitat characteristics. Enigmatic freshwater mussel declines, often characterized by sudden mass mortality events, pose significant challenges to conservation efforts. The Clinch River, a freshwater biodiversity hotspot in Virginia and Tennessee, USA, has experienced several enigmatic mass mortality events since 2016. Studies have reported bacteria associated with moribund Pheasantshell (Actinonaias pectorosa) during mortality events in the Clinch River, specifically Yokenella regensburgei. Despite reports of bacterial infection, little is known about their role as pathogens. Through a multiyear case-control study, combining in-situ experiments, field surveys, histology, bacterial isolation, and high-throughput sequencing, we assessed the role of bacteria in Pheasantshell (Actinonais pectorosa) mortality at three sites in the Clinch River. Between May 2021 and December 2023, we collected 21 wild moribund free-living A. pectorosa and 68 hatchery-reared A. pectorosa maintained in silos at the same sites and investigated differences in pathology and microbiologye between groups. No silo mussels presented clinical signs of disease, or gross or microscopic lesions associated with pathological conditions leading to mortality. Our findings reveal a significant association between Yokenella regensburgei and severe multisystemic and multifocal infiltrative hemocytosis with necrosis, consistent with sepsis. Lesions associated with yokenellosis were of sufficient severity and physiological significance to explain mortality in infected hosts. Although our study does not explain the cause of these infections, it confirms that mussels at our study sites are ultimately dying with an infectious disease and that Y. regensburgei can be pathogenic in free-living mussels. Our results underscore the importance of considering bacterial diseases in wild mussel populations and emphasize the need for further research to elucidate the epidemiology and pathogenicity of Y. regensburgei. Overall, our study highlights the importance of integrated approaches combining pathology, microbiology, and epidemiology in freshwater mussel conservation efforts. [ABSTRACT FROM AUTHOR]

Hyriopsis cumingii is a major freshwater pearl mussel in the world. In order to investigate the functional roles of the growth- and mineralization-related genes involved in the pearl formation process after the inserting nucleus into the mantle tissue of H. cumingii, we conducted a transcriptome analysis of data from different time periods after the pearl-nucleus insertion. We screened a total of 1,898 growthrelated unigenes and 716 mineralization-related unigenes, including 12 growthrelated differential genes and eight mineralization-related differential genes that showed sustained differential expression throughout the pearl formation. The results of the gene expression patterns among samples at different time points showed that the Mcon group and theM05d group clustered together, theM50d group and the M90d group clustered together, while the M20d group clustered separately. The overall density distribution of differential gene analysis at different periods after pearlnucleus insertion of H. cumingii, cluster analysis, differential gene analysis, differential gene differential, and co-expression analysis together revealed that growth and mineralization-related genes have the same expression pattern and jointly regulate pearl formation. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment revealed that the same functional cluster and pathway were together present on the enrichment results of both growth- and mineralization-related genes, suggesting a synergistic effect between growth and mineralization. We found that genes such as bone morphogenetic proteins (BMPs) and calmodulin (CALM) are jointly involved in growth and mineralization processes. The study indicate that growth genes cooperate with mineralization genes to play biological roles in the early process of pearl formation in H. cumingii. [ABSTRACT FROM AUTHOR]

Background: Freshwater mussels are important keystone and indicator species of aquatic ecosystems. Recent advances in sensor technology facilitate applications to individually track mussels and to record and monitor their behavior and physiology. These approaches require the attachment of sensor devices as "backpacks" to the outer shell surface. The interpretation of such data makes it necessary to understand the influence of these attachments on the horizontal and vertical movement behaviors of freshwater mussels. Over a series of mesocosm experiments, this study systematically investigated the effects of three size- and wiring-specific variants of artificially attached backpacks on the horizontal and vertical movement behavior of Anodonta anatina. Results: Across all experiments, equipping mussels with backpacks did not result in a significant influence on horizontal movement for any of the backpack variants. In contrast to this finding, the big backpacks with a high ratio between backpack volume and mussel length resulted in a significantly negative effect on vertical movement, indicating a potential for adverse effects of such devices on mussels, especially in natural settings. Conclusions: The findings of this study show that assessing the effects of attached devices on mussels requires a species-specific evaluation of potential impacts on the endpoints of interest. Especially for vertical movement patterns, selection of the smallest available devices appears mandatory. [ABSTRACT FROM AUTHOR]

The present study uses results of eddy‐resolving numerical simulations to investigate the open channel flow over large clusters of freshwater mussels (Unio elongatulus) partially buried in a rough, gravel bed. The density of the mussels forming the array varies from 26 to 500 mussels/m2. The flow structure is analyzed at large distances from the leading edge of the mussel bed, where the flow can be considered fully developed. The effects of changing the mussel bed density, the filtering discharge, the burial level and the roughness of the bed surface in which mussels are burrowed, are investigated in terms of flow field, turbulent structures, drag forces, and bed shear stresses. It is found that strong interactions occur between energetic eddies generated by the larger gravels on the exposed bed surface and by the mussel shells. Simulations results show that for a burial depth close to 50% and a ratio between the average gravel size and the mussel protruding height of 0.13, the shell induced turbulence becomes dominant for mussel bed densities around 50 mussels/m2. The influence of the bed roughness becomes less relevant with increasing mussel density, as the generation of energetic eddies is mostly controlled by mussel‐to‐mussel interactions. For fixed bed roughness, burial level and filtering velocity, the mean streamwise drag force and the associated drag coefficient for the exposed part of each mussel decrease with increasing mussel density, even if strong variations are observed for individual mussels. For constant mussel bed density and burial level, the mean streamwise drag force and the mean drag coefficient decrease slightly with increasing bed roughness. Increasing the burial level decreases not only the drag forces but also the drag coefficients because of the more streamlined shape of the top of the mussels. Strong active filtering acts toward decreasing the mean streamwise force and the mean drag coefficient. The spanwise drag forces contribute significantly to the total drag force, especially for high mussel bed densities. Based on smooth bed calculations, bed‐averaged shear stresses are reduced in highly dense clusters. Key Points: Mussel‐to‐mussel interactions are important for dense arrays and influence flow structure and turbulenceEddy resolving simulations showed that the effect of bed roughness become less significant with increasing mussel bed densityIn dense clusters of mussels, forces on the shells and bed shear stresses are reduced thus favoring mussel stability [ABSTRACT FROM AUTHOR]

Family Parvoviridae consists of small, non-enveloped viruses with linear, single-stranded DNA genomes of approximately 4-6 kilobases, subdivided into three subfamilies, Parvovirinae, Densovirinae, and Hamaparvovirinae, and unassigned genus Metalloincertoparvovirus. Parvoviruses of aquatic animals infect crustaceans, mollusks, and finfish. This review describes these parvoviruses, which are highly host-specific and associated with mass morbidity and mortality in both farmed and wild aquatic animals. They include Cherax quadricarinatus densovirus (CqDV) in freshwater crayfish in Queensland, Australia; sea star-associated densovirus (SSaDV) in sunflower sea star on the Northeastern Pacific Coast; Clinch densovirus 1 in freshwater mussels in the Clinch River, Virginia, and Tennessee, USA, in subfamily Densovirinae; hepatopancreatic parvovirus (HPV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV) in farmed shrimp worldwide; Syngnathid ichthamaparvovirus 1 in gulf pipefish in the Gulf of Mexico and parts of South America; tilapia parvovirus (TiPV) in farmed tilapia in China, Thailand, and India, in the subfamily Hamaparvovirinae; and Penaeus monodon metallodensovirus (PmMDV) in Vietnamese P. monodon, in unassigned genus Metalloincertoparvovirus. Also included in the family Parvoviridae are novel parvoviruses detected in both diseased and healthy animals using metagenomic sequencing, such as zander parvovirus from zander in Hungary and salmon parvovirus from sockeye salmon smolts in British Columbia, Canada. [ABSTRACT FROM AUTHOR]

The shells of freshwater mussels, commonly found at archaeological sites associated with the Kodjadermen-Gumelnița-Karanovo VI human groups (5th millennium BCE, Romania and Bulgaria), were a significant dietary component for this population. The organic matrix of these ancient shells is often well-preserved and can be analysed using stable isotopes.This study establishes the empirical relationship between the isotopic composition of the acid-insoluble shell organic matrix (AIM) and the soft tissues of modern Unio tumidus. A quality criterion for AIM (C:N ratio 3.6 (3.3–

ABSTRACT Niche partitioning promotes species coexistence. Yet, it remains unclear how phylogeny and morphology influence the trophic niches of closely related aquatic species with shared feeding modes. Freshwater mussels (Family: Unionidae) are a group of filter‐feeding bivalves that are ideal for investigating mechanisms of niche partitioning. Particle size selection and patterns of ingestion are controlled by gill latero‐frontal cirri density (CD) and the number of cilia per cirrus (CC). We investigated trophic assimilation and niche area using stable isotope signatures (𝛿13C and 𝛿15N) and gill morphology with scanning‐electron microscopy for a diverse mussel assemblage from the Sipsey River, Alabama, USA. We predicted that (1) trophic niches and gill morphology would differ within and among species across sites; (2) co‐occurring species would partition food resources; (3) greater phylogenetic distances among species would result in increased trophic dissimilarity; (4) more CC and higher CD would result in a narrower trophic niche area, or more constrained range of food items assimilated. We found that (1) species identity and site influenced gill morphology and stable isotope signatures but that the trophic niche area of a species was only affected by species identity; (2) the average proportion of niche area overlap between co‐occurring species was low across sites (0.04 to 0.18); (3) trophic dissimilarity among species increased with phylogenetic distance; (4) CD but not the number of CC negatively related to trophic niche area. Our results indicate that gill morphology and evolutionary history are likely key factors governing the trophic niches of mussels. In addition, intraspecific variation in gill morphology across sites may either reflect a phenotypic response to differences in local resource availability or suggest that other mechanisms shape particle selection. Examining the interplay among the trophic niche, phylogeny, and morphology among functionally similar species further informs our understanding of the mechanisms facilitating their coexistence.

Freshwater mussels perform important ecological functions in ecosystems, such as water filtration and energy cycling. Unlike marine bivalves, freshwater mussels have unique characteristics including internal fertilization and parental care. Some freshwater mussels are facing a high risk of extinction due to several factors such as climate change and habitat loss. Potomida semirugata (Lamarck, 1819) is one of the freshwater mussel species with a high risk of extinction and listed as Endangered in the Red List of the International Union for Conservation of Nature. Here, we present the first F-type mitogenome sequence of P. semirugata. The genome was sequenced on an Illumina high-throughput platform from a P. semirugata specimen collected from the Tersakan River (Turkey). The 16,093 bp mitochondrial genome sequence contains 13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs. Phylogenetic analysis placed P. semirugata in the Lamprotulini clade with Potomida littoralis, as expected. Potomida semirugata is a poorly studied species and the genomic resource provided here will contribute to a better understanding of its biological characterization.

Contamination with plastics of small dimensions (

Freshwater mussels (Bivalvia, Unionida) play essential roles in the well-functioning of ecosystems, even providing essential services to humans. However, these bivalves face numerous threats (e.g. habitat loss and fragmentation, pollution, introduction of invasive species, and climate change) which have already led to the extinction of many populations. This underscores the need to fully characterize the biology of these species, particularly those, such as Potomida acarnanica, that are still poorly studied. This study presents the first mitogenome of P. acarnanica (Kobelt, 1879), an endemic species of Greece with a distribution limited to only two river basins. The mitochondrial genome of a P. acarnanica specimen, collected at Pamisos River (Peloponnese, Greece), was sequenced by Illumina high-throughput sequencing. This mitogenome (16,101 bp) is characterized by 13 protein-coding genes, 22 transfer RNA and 2 ribosomal RNA genes. The size of this mitogenome is within the range of another Potomida mitogenome already published for the species Potomida littoralis. In the phylogenetic inference, P. acarnanica was recovered as monophyletic with P. littoralis mitogenome in the Lamprotulini tribe, as expected. This genomic resource will assist in genetically characterizing the species, potentially benefiting future evolutionary studies and conservation efforts.

This study is based on a natural experiment carried out in the Biebrza National Park, Poland. The study site was a channel inhabited by Anodonta anatina, A. cygnea, Unio pictorum and U. tumidus. The deepening of the channel to restore ecosystem connectivity provided an opportunity to conduct this study. Mussels were collected before dredging, held in captivity for 48 h, measured, individually tagged and released post-dredging to the same 5-m channel sections they originated from. They were subsequently monitored for three consecutive years. Mussel survival remained high throughout the study, and no increased mortality in the year following reintroduction was observed. There was no growth retardation. Mussel mobility was low, with most individuals remaining in the same channel section in which they were released. Recolonisation patterns were consistent with the composition of mussel communities in adjacent unaffected habitats. Although dredging drastically changes mussel habitat, some characteristics: microclimate, water chemistry, nutrient availability and host fish can remain adequate. Our study shows that reintroducing mussels to the same site can serve as an effective mitigation conservation measure and can be preferable to translocation, particularly when carried out under time pressure with limited possibilities of assigning appropriate destination sites. [ABSTRACT FROM AUTHOR]

Wine is renowned for its rich content of polyphenols, including resveratrol (Res), known for their health promoting properties. Steamed clam with wine, a popular Mediterranean delicacy that highlights the role of wine as a key ingredient. However, despite these benefits, resveratrol's low bioavailability poses challenges. Could the process of steaming together with clam alter the digestive fate of resveratrol from wine? This study explores the potential of proteoglycan-based nanoparticles from freshwater clam (CFNPs) as a delivery vehicle for enhancing the stability and bioavailability of resveratrol, compared with wine and free Res' solution, aiming to elucidate mechanisms facilitating Res' absorption. The results demonstrated that CFNPs can effectively encapsulate Res with an efficiency over 70%, leading to a uniform particle size of 70.5±0.1 nm (PDI < 0.2). Resveratrol loaded in CFNPs (CFNPs-Res) exhibited an improved antioxidant stability under various conditions, retaining over 90% of antioxidant capacity after three-day storage at room temperature. The controlled-release profile of Res loaded in CFNPs fits both first and Higuchi order kinetics and was more desirable than that of wine and the free Res. Examined by the simulated gastrointestinal digestion, CFNPs-Res showed a significantly higher bioaccessibility and antioxidant retention compared to free Res and the wines. The discovery and use of food derived nanoparticles to carry micronutrients and antioxidants could lead to a shift in functional food design and nutritional advice, advocating much more attention on these entities over solely conventional molecules. [ABSTRACT FROM AUTHOR]

Freshwater bivalve mussels in the order Unionida are highly endangered ecosystem engineers with a parasitic lifecycle necessitating a fish host to metamorphose from larval glochidia to juvenile mussel. While many species are broadcast spawners and release a large number of glochidia into the water column, many other species have a variety of highly evolved lure mechanisms and mantle displays to attract hosts to ensure a more targeted infestation. Almost all lure mussels are found exclusively in North America, with only one European species (Unio crassus) occasionally displaying a host attraction behaviour referred to as larval spurting. Here, I present evidence that the depressed river mussel (Pseudanodonta complanata) exhibits mantle displays to attract fish to gravid mussels for a targeted infestation, the first description of mantle displays in Europe. [ABSTRACT FROM AUTHOR]

The present study was designed to reveal the relative impact of water quality changes induced by the climate’s influence and some waste discharge on the existence and prevalence of some gill parasite species in the Nile tilapia inhabiting Rosetta Branch, the River Nile. Both fish (1600 Nile tilapia fish) and water samples were randomly collected seasonally from four sites (El-Kanater El-Khayria, El-Qatta, Tamalay, and Kafr ElZayat) along the Rosetta Branch of the Nile, which receives some types of wastewater. Parasitological examination of fish revealed the presence of Trichodina sp., Ambiphyra sp., Cichlidogyrus tilapiae, the encysted metacercaria of Clinostomum phalacrocoracis, and the larval stage of the freshwater mussels, Glochidia. The highest parasite prevalence was recorded at Kafr El-Zayat station, followed by El-Qatta and Tamalay. On the other hand, the autumn season recorded the highest parasitic prevalence, followed by winter, summer, and spring. The histological examination of the gills of the infected fish revealed severe histological alterations and the presence of different histozoic parasites. The most significant water parameters influencing the parasitic prevalence were temperature, pH, DO, BOD, and ammonia. The outcomes reveal that water parameter, temperature, pH, DO, BOD, and TAN are important factors affecting the different parasite prevalence values of the infected tilapia fish. [ABSTRACT FROM AUTHOR]

Simple Summary: The global distribution of the genus Corbicula is driven by multiple hermaphroditic lineages. In Argentina, there remains a lack of comprehensive understanding of the current distribution, identity, and genetic relatedness of invasive Corbicula lineages. Reviewing 15 populations, we discriminate extant lineages based on both morphology and genetics in Argentina. We identified two lineages: AR morphotype (FW5 haplotype) and CS morphotype (FW17 haplotype). These lineages exhibited virtually segregated distributions, however, intermediate morphotypes found in northeastern Argentina suggest the presence of hybrids. Our study clarifies Corbicula identity and distribution, offering insights into invasion patterns in a wide geographic region. The broad global distribution of freshwater clams belonging to the genus Corbicula is driven by multiple hermaphroditic lineages. These lineages, characterized by shared morphological traits and phenotypic plasticity, pose challenges to morphological identification. Genetic markers, such as the mitochondrial COI gene, play a crucial role in delineating these lineages and their ranges. Morphotypes represent observed phenotypic variations, while lineages are defined based on genetic markers. Here, we comprehensively review Corbicula's distribution in Argentina, discriminate extant lineages based on both morphological and genetic (COI) data, and describe variations in internal and external morphologies using 15 Argentine populations. Genetic analyses identified two mitochondrial lineages: the AR morphotype (FW5 haplotype) and CS morphotype (FW17 haplotype). Strikingly, despite having similar vectors, origins, and invasive stages, Corbicula lineages exhibit virtually segregated distributions. However, mitochondrial haplotypes are found in sympatry mainly in northeastern Argentina where individuals with intermediate morphotypes exist, suggesting the presence of hybrids due to maternal genome retention. These findings contribute to the clarification of the identity and distribution of Corbicula lineages in Argentina, where the genus has been found for over half a century. Similar studies are needed in other areas to better understand the invasion patterns of this successful and adaptable group. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems and the biodiversity they support are facing unprecedented threats, exemplified by broad declines of freshwater mussels within a global biodiversity hotspot. The Rocky Mountain Ridged Mussel (Gonidea angulata) is an at-risk species in Canada, with limited information on population age structure. Maximum age of the species was found to be 50 years, by counting winter annuli and validated by isotopic oxygen analysis. Employing a Bayesian Generalized Linear Mixed Model (GLMM), results showed mussels from river habitat were predicted to have faster growth rates than mussels from lake habitats, highlighting the impact of local environmental conditions, including temperature variations, primary productivity, and water quality, on mussel growth dynamics. Of concern was the limited evidence of juvenile recruitment, with the majority of specimens potentially representing an ageing population. This pattern potentially signals an early warning of impending population decline. Our results underscore the necessity of monitoring age structure as a vital component of assessing population health of freshwater mussels and the importance of understanding local environmental conditions when determining age. [ABSTRACT FROM AUTHOR]

Freshwater mussels perform important ecological functions in ecosystems, such as water filtration and energy cycling. Unlike marine bivalves, freshwater mussels have unique characteristics including internal fertilization and parental care. Some freshwater mussels are facing a high risk of extinction due to several factors such as climate change and habitat loss. Potomida semirugata (Lamarck, 1819) is one of the freshwater mussel species with a high risk of extinction and listed as Endangered in the Red List of the International Union for Conservation of Nature. Here, we present the first F-type mitogenome sequence of P. semirugata. The genome was sequenced on an Illumina high-throughput platform from a P. semirugata specimen collected from the Tersakan River (Turkey). The 16,093 bp mitochondrial genome sequence contains 13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs. Phylogenetic analysis placed P. semirugata in the Lamprotulini clade with Potomida littoralis, as expected. Potomida semirugata is a poorly studied species and the genomic resource provided here will contribute to a better understanding of its biological characterization. [ABSTRACT FROM AUTHOR]

Sinosolenaia oleivora (Bivalve, Unionida, Unionidae), is a near-endangered edible mussel. In 2022, it was selected by the Ministry of Agriculture and Rural Affairs as a top-ten aquatic germplasm resource, with potential for industrial development. Using Illumina, PacBio, and Hi-C technology, a high-quality chromosome-level genome of S. oleivora was assembled. The assembled S. oleivora genome spanned 2052.29 Mb with a contig N50 size of 20.36 Mb and a scaffold N50 size of 103.57 Mb. The 302 contigs, accounting for 98.41% of the total assembled genome, were anchored into 19 chromosomes using Hi-C scaffolding. A total of 1171.78 Mb repeat sequences were annotated and 22,971 protein-coding genes were predicted. Compared with the nearest ancestor, a total of 603 expanded and 1767 contracted gene families were found. This study provides important genomic resources for conservation, evolutionary research, and genetic improvements of many economic traits like growth performance. [ABSTRACT FROM AUTHOR]

Contamination with plastics of small dimensions (<1 µm) represents a health concern for many terrestrial and aquatic organisms. This study examined the use of plastic-binding peptides as a coating probe to detect various types of plastic using a plasmon nano-gold sensor. Plastic-binding peptides were selected for polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) based on the reported literature. Using nAu with each of these peptides to test the target plastics revealed high signal, at 525/630 nm, suggesting that the target plastic limited HCl-induced nAu aggregation. Testing with other plastics revealed some lack of specificity but the signal was always lower than that of the target plastic. This suggests that these peptides, although reacting mainly with their target plastic, show partial reactivity with the other target plastics. By using a multiple regression model, the relative levels of a given plastic could be corrected by the presence of other plastics. This approach was tested in freshwater mussels caged for 3 months at sites suspected to release plastic materials: in rainfall overflow discharges, downstream a largely populated city, and in a municipal effluent dispersion plume. The data revealed that the digestive glands of the mussels contained higher levels of PP, PE, and PET plastic particles at the rainfall overflow and downstream city sites compared to the treated municipal effluent site. This corroborated earlier findings that wastewater treatment could remove nanoparticles, at least in part. A quick and inexpensive screening test for plastic nanoparticles in biological samples with plasmonic nAu-peptides is proposed. [ABSTRACT FROM AUTHOR]

During an epidemiological survey following a mortality event of freshwater mussels in 2018 in the Embarrass River, Wisconsin, USA, we identified a novel microsporidian parasite in the ovaries of mucket (Actinonaias ligamentina), plain pocketbook (Lampsilis cardium), and fatmucket (Lampsilis siliquoidea) (Unionidae). Histopathology showed round-to-oval microsporidian spores in the cytoplasm of oocytes in 60% (3/5) of female mucket, 100% (4/4) of female plain pocketbook, and 50% (1/2) of female fatmucket. Using transmission electron microscopy, we found that mature spores were round-to-oval and measured 4.13 ± 0.64 µm (3.14–5.31) long by 2.88 ± 0.37 µm (2.36–3.68) wide. The spores had a thin electron-dense exospore with a spiky "hairy" coat, a thick electron lucent endospore, diplokaryotic nuclei, a polar vacuole, and 27–28 polar filaments arranged in 1–3 rows. Sequencing of the small subunit rRNA produced a 1356 bp sequence most similar to that of Pseudonosema cristatellae (92%), and phylogenetic analysis grouped it within the freshwater Neopereziida. Genetic, morphological, and ultrastructural characteristics did not closely match those of other Pseudonosema spp., and a new genus and species, Hirsutonosema embarrassi n. gen. n. sp., were designated. Additional studies could evaluate host susceptibility, distribution, seasonality, transmission, and lethal or sub-lethal effects of this parasite on freshwater mussels. [ABSTRACT FROM AUTHOR]

Freshwater mussels (Bivalvia, Unionida) play essential roles in the well-functioning of ecosystems, even providing essential services to humans. However, these bivalves face numerous threats (e.g. habitat loss and fragmentation, pollution, introduction of invasive species, and climate change) which have already led to the extinction of many populations. This underscores the need to fully characterize the biology of these species, particularly those, such as Potomida acarnanica, that are still poorly studied. This study presents the first mitogenome of P. acarnanica (Kobelt, 1879), an endemic species of Greece with a distribution limited to only two river basins. The mitochondrial genome of a P. acarnanica specimen, collected at Pamisos River (Peloponnese, Greece), was sequenced by Illumina high-throughput sequencing. This mitogenome (16,101 bp) is characterized by 13 protein-coding genes, 22 transfer RNA and 2 ribosomal RNA genes. The size of this mitogenome is within the range of another Potomida mitogenome already published for the species Potomida littoralis. In the phylogenetic inference, P. acarnanica was recovered as monophyletic with P. littoralis mitogenome in the Lamprotulini tribe, as expected. This genomic resource will assist in genetically characterizing the species, potentially benefiting future evolutionary studies and conservation efforts. [ABSTRACT FROM AUTHOR]