Search Results (45)

Invasive species require long-term characterization of their shifting population dynamics to understand their environmental impacts and socio-economic effects. The dynamics of freshwater bivalves depend on their biology, which is influenced by the vulnerability of the ecosystems. This study evaluates the coexistence of Corbicula fluminea and C. largillierti in a stream in the Argentine Pampa, integrating density, size, and reproduction. In this stream, characterized by a temperate climate and hydrological fluctuations, live specimens of both species were sampled monthly using a 0.07 m² cylinder. The anteroposterior length of each specimen was measured, and size distributions were analyzed by decomposing normal modes using the least-squares method. Gonadal cycles were compared with data from the previous literature. Since 2004, C. fluminea has dominated the system with significantly higher densities. Both species exhibited contrasting reproductive cycles. Hydrological instability in the stream limited both species. C. fluminea dominated due to its greater resilience and longevity under stress. In contrast, C. largillierti prioritized initial rapid growth, making it more sensitive to fluctuations. These results highlight that environmental instability conditions invasive success and interspecific competition in freshwater systems. Full article

Background/Objectives: Water scarcity is driving the development of strategies for treating municipal wastewater (MW) to enable its safe reuse. Nonetheless, MW contains contaminants of emerging concern (CECs), such as pharmaceuticals and antimicrobial-resistant (AMR) bacteria, which require innovative treatment technologies. In this context, Corbicula fluminea, an invasive freshwater clam, presents a high biofiltration capacity, and its environmental impact could be mitigated by assigning it a beneficial role in wastewater treatment. Methods: The ability of C. fluminea to remove chemical and biological CECs from real MW secondary-treated effluents was assessed. The effects of real wastewater on the clams’ microbiome and on colony-forming unit (CFU) counts in their soft tissues were also assessed. Results: Under real conditions, the clams achieved over 73% removal for 3 chemical CECs after 24 h, with an average removal of approximately 39%. The clams showed recovery of both CFU counts and microbial community composition, dominated by opportunistic and stress-tolerant groups in the presence of pharmaceuticals. The removal of multidrug-resistant bacteria was evaluated; despite real wastewater reducing clearance rates, the clams significantly reduced these bacteria within 24 h. Conclusions: These results demonstrate that C. fluminea can serve as an effective polishing treatment, improving effluent quality, supporting control of this invasive species. Full article

Freshwater clams (Corbicula spp.), commonly known as shijimi in East Asia, have long been valued for their functional and nutritional properties. In this review, we summarise the physiological effects of hot water extracts derived from Taiwanese freshwater clams (FCE), particularly in relation to metabolic syndrome and other lifestyle-related disorders. Traditionally, shijimi has been used to alleviate hepatic dysfunction and symptoms associated with alcohol consumption. FCE significantly suppresses galactosamine-induced increases in serum aspartate aminotransferase and alanine aminotransferase. In addition, FCE reduces alcohol-induced hepatic lipid accumulation and lowers hepatic cholesterol levels. FCE also influences alcohol metabolism: animals receiving FCE exhibit lower blood alcohol concentrations and a faster rate of alcohol clearance following ethanol administration. These findings suggest that shijimi may protect against alcohol- or drug-induced liver damage, potentially by enhancing alcohol metabolism. Beyond its role in liver protection, shijimi has been associated with the alleviation of jaundice, possibly through increased bile secretion linked to improved cholesterol homeostasis. Supporting this, studies using models of exogenous hypercholesterolemia show that FCE lowers both serum and hepatic cholesterol levels in a dose-dependent manner. Overall, traditional claims regarding the hepatoprotective effects of shijimi are increasingly supported by mechanistic and molecular evidence. This is the first clarified review of the various effects of shijimi. Full article

This study investigated heavy metal bioaccumulation, pollution sources, and human health risks in the Wujiang and Zhenjiang rivers, the major headwaters of the Beijiang River in southern China. Concentrations of 11 heavy metals (Fe, Mn, Ba, Zn, As, Cu, Ni, Cr, Co, Cd, Pb) in surface water, sediments, and the soft tissues of four bivalve species (Corbicula fluminea, Limnoperna fortunei, Unio douglasiae, and Anodonta woodiana) were determined. Results showed that surface water remained below pollution thresholds, whereas sediments in the Wujiang River exhibited moderate-to-heavy Cd, As, Pb, and Zn contamination linked to historical Pb-Zn mining. Among the two better-represented species, C. fluminea showed relatively high As and Zn concentrations, whereas L. fortunei showed relatively high Cu accumulation. Data for U. douglasiae and A. woodiana were treated as preliminary observations because of their limited sample sizes. Biota-sediment accumulation factor (BSAF) values indicated that Mn, Cu, Cd, Zn, Ni, and Cr were actively accumulated beyond sediment concentrations, whereas As and Pb showed limited sediment-to-biota transfer. Multivariate analysis of the two better-represented species indicated species-related differences in tissue metal profiles, with patterns consistent with both natural geogenic inputs and historical Pb-Zn mining activities. All four species posed potential non-carcinogenic health risks to consumers, with As and Mn as the dominant risk contributors. These findings underscore the necessity of multi-species biomonitoring and consumption advisories in mining-impacted watersheds. Full article

Corbicula fluminea protein (CFP) and cyanidin-3-O-glucoside (C3G) are natural nutrient fortifiers. During consumption or processing, they may interact with each other, inducing alternations in their structural and functional properties. However, nothing was known about the mechanism of their interaction and their synergistic antioxidant effect. In this research, C3G was physically mixed with CFP to simulate practical scenarios. The impact of the presence of C3G on the multispectral characteristics, antioxidant activity, and particle properties of CFP was examined and compared to chemically fabricated C3G-CFP covalent conjugates. The results indicate that C3G tended to spontaneously bind to CFP and formed compact non-covalent complex, with hydrophobic forces predominantly governing the interaction. This binding resulted in the statically quenched intrinsic fluorescence of CFP, accompanied by a dynamic model. Moreover, C3G preferentially induced Trp residue in CFP exposed to a more polar microenvironment, yet it exerted nearly no effects on CFP when analyzed using ultraviolet–visible (UV-Vis) spectroscopy and synchronous fluorescence spectroscopy (SFS). Additionally, although the formed non-covalent complex demonstrated strengthened antioxidant capacity, C3G displayed an antagonistic effect with CFP, whereas lower C3G concentrations led to synergistic effects in covalent conjugates. These findings provide new insights into the effective application of C3G and CFP as nutritional antioxidants. Full article

Bisphenol A (BPA) and its substitutes have been identified as endocrine-disrupting chemicals (EDCs). However, little information is available on their reproductive endocrine disruptive effects in mollusks. This study cloned the full-length sequence (2434 bp) of the estrogen-related receptor (ERR) gene in the freshwater bivalve Corbicula fluminea and performed a bioinformatics analysis and tissue-specific expression analysis. We further examined the expression of the CfERR gene after exposure to E2, BPA, and their substitutes (BPS, BPF, and BPAF) at 1, 10, and 100 μg/L for 0, 1, 7, 14, 21, and 28 days. The results showed that CfERR is a nuclear protein with a typical structure. Phylogenetic analysis indicated a high degree of similarity among bivalve species. The high expression of CfERR in the gonad suggested its important role in reproductive regulation. The exposure experiment confirmed that CfERR showed a time- and dose-dependent upregulation in response to all pollutants, with BPS and BPAF exhibiting stronger estrogenic interference effects. This study facilitates a better understanding of the reproductive regulation of bivalves and provides data to support the toxicity evaluation of BPA and its substitutes. Full article

As benthic filter feeders, bivalve mollusks serve as ideal biological indicators. Bisphenol A (BPA) and its substitutes (BPS, BPF, and BPAF) are endocrine disruptors with reproductive toxicity, targeting estrogen receptors (ERs). However, their binding sites and affinity for shellfish ERs remain unclear. This study aims to identify ER binding sites of BPA and its substitutes, compare toxicity via molecular docking, and validate results through exposure experiments. The full-length cDNA of Corbicula fluminea ER was cloned using the RACE technique for the first time, the sequence length is 2138bp. Homologous models of LBD sequences from Danio rerio, C. fluminea, Azumapecten farreri, and Ruditapes philippinarum ERs were constructed via homology modeling and screened for optimal fit. Hydrogen bonds were observed during the docking process, with interaction sites including Glu-66, Arg-177, and other amino acid residues. Exposure experiments (1, 10, and 100 μg/L) showed an enhancement in ER mRNA expression. Based on the docking energies and results of the exposure experiments, it was concluded that the toxicity of BPA and BPS is similar and greater than that of BPF and BPAF. This study provides data for a reproductive risk assessment and aquatic toxicological monitoring of bisphenols. Full article

Cadmium (Cd) accumulation by benthic organisms poses a significant threat to aquatic environmental safety. Both vegetation and water velocity in rivers could influence this process, yet their coupled interaction mechanisms remain unclear. This study used laboratory flume experiments to simulate four scenarios: static water (C0), pure water velocity (C+H), vegetation-water velocity (V+H), and coexistence of vegetation-water velocity-Corbicula fluminea (C. fluminea) (C+V+H). The dynamics of Cd release from sediment to overlying water and its bioaccumulation within C. fluminea were investigated. A mathematical model coupling Cd release, diffusion, and C. fluminea bioaccumulation was developed based on the lattice Boltzmann method (LBM). The results showed that compared to the non-vegetation group (C+H), the presence of vegetation (V+H, C+V+H) initially reduced sediment resuspension and Cd release. However, the turbulence induced by vegetation significantly increased the Cd diffusion coefficient and equilibrium concentration in the water. Consequently, Cd accumulation in C. fluminea within the vegetation-water velocity group (C+V+H) was significantly higher than in the pure water velocity group (C+H). The established LBM model exhibited good simulation accuracy (for overlying water Cd concentration: R² = 0.8201–0.942; for C. fluminea Cd concentration: R² = 0.7604–0.8191) and successfully reproduced the processes of Cd release and bioaccumulation under varying vegetation-water velocity conditions. This study elucidates the mechanism by which vegetation promotes Cd accumulation in C. fluminea by altering water velocity structure and diffusion characteristics, providing crucial theoretical parameters for multi-media migration and transformation models of heavy metals in complex water velocity environments and for early warning systems concerning Cd accumulation risks in riverine organisms. Full article

Understanding the biodiversity of aquatic communities and the underlying mechanisms that shape biodiversity patterns and community dynamics is crucial for the effective conservation and management of freshwater ecosystems. However, traditional survey methods often fail to comprehensively capture species diversity, particularly for low-abundance taxa. Moreover, studies integrating both metazoan and fish communities at fine spatial scales remain limited. To address these gaps, we employed a multi-marker eDNA metabarcoding approach, targeting both the 12S and 18S rRNA gene regions, to comprehensively investigate the composition of metazoan and fish communities in the Yujiang River. A total of 12 metazoan orders were detected, encompassing 15 families, 21 genera, and 19 species. For the fish community, 32 species were identified, belonging to 25 genera, 10 families, and 7 orders. Among these, Adula falcatoides and Coptodon zillii were identified as the most prevalent and abundant metazoan and fish species, respectively. Notably, the most prevalent fish species, C. zillii and Oreochromis niloticus, are both recognized as invasive species. The Bray–Curtis distance of metazoa (average: 0.464) was significantly lower than that of fish communities (average: 0.797), suggesting higher community heterogeneity among fish assemblages. Beta-diversity decomposition indicated that variations in the metazoan and fish communities were predominantly driven by species replacement (turnover) (65.4% and 70.9% for metazoa and fish, respectively) rather than nestedness. Mantel tests further revealed that species turnover in metazoan communities was most strongly influenced by water temperature, while fish community turnover was primarily affected by water transparency, likely reflecting the physiological sensitivity of metazoans to thermal gradients and the dependence of fish on visual cues for foraging and habitat selection. In addition, a co-occurrence network of metazoan and fish species was constructed, highlighting potential predator-prey interactions between native species and Corbicula fluminea, which emerged as a potential keystone species. Overall, this study demonstrates the utility of multi-marker eDNA metabarcoding in characterizing aquatic community structures and provides new insights into the spatial dynamics and species interactions within river ecosystems. Full article

Freshwater bivalves play essential ecological roles in ecosystems, but they are among the most threatened fauna worldwide. Despite receiving industrial and domestic wastes, the Guandu River is the main source of drinking water for more than nine million people in the Rio de Janeiro metropolitan region. This study aimed to assess how infaunal bivalves respond to water and sediment quality in the Guandu River basin. Samples were collected at 10 sites across reservoirs, lotic, and lentic systems during cold–dry and warm–rainy seasons. Four bivalves were identified: Anodontites trapesialis, Diplodon ellipticus, Corbicula fluminea (non-native), and C. largillierti (non-native). Native species were restricted to two lentic sites at Guandu Lagoon, with the poorest environmental quality, significantly affected by high chlorophyll a and ammonia in the water. In contrast, C. fluminea was widely distributed and more abundant in the basin but restricted to less degraded sites, suggesting a lower tolerance to environmental pollution. Multivariate analyses indicated significant differences in environmental conditions and species–environment correlation. The non-native species spread and poor environmental quality threaten native bivalves in the Guandu River basin, leading them to a local extinction risk. Results highlight the need for effective management and conservation actions to protect biodiversity in tropical river basins. Full article

The Seomjin River estuary is a key habitat for the Asian clam (Corbicula fluminea), contributing significantly to the local economy and aquatic biodiversity in South Korea. However, long-term reductions in upstream discharge, geomorphological alterations, land reclamation, and climate change have intensified saltwater intrusion, gradually displacing clam habitats upstream. This study employed the Environmental Fluid Dynamics Code (EFDC) model to simulate salinity distribution and evaluate optimal environmental flow strategies for clam conservation. Simulation results indicated that maintaining a minimum upstream flow of 23 m³/s was essential to prevent salinity levels from exceeding the critical threshold of 20 psu at Seomjin Bridge, a key habitat site. During neap tides, reduced tidal flushing led to prolonged saltwater retention, elevating salinity levels and increasing the risk of mass clam mortality. A historical event in May 2017, when salinity exceeded 20 psu for over four consecutive days, resulted in a major die-off. This study successfully reproduced that event and evaluated mitigation strategies. A combined approach involving increased dam releases and temporary reductions in intake withdrawal was assessed. Notably, a pulse release strategy supplying an additional 9.9–10.37 m³/s (total 30.4 m³/s) over three days during neap tide effectively limited critical salinity durations to fewer than four days. The preservation of Asian clams in the Seomjin River estuary is a sustainability measure not only from an ecological perspective but also from a cultural one. Full article

Microplastics (MPs) are a worldwide contaminant of significant environmental concern due to their persistence, widespread distribution, and toxic potential. These plastic particles are taken up by invertebrates such as bivalves. Previous studies have indicated that MPs can serve as carriers for other contaminants, such as heavy metals, thereby increasing their bioavailability to organisms, with unpredictable ecological consequences. Therefore, the main aim of this study was to evaluate the effects of exposure to MPs, cadmium (Cd), and their mixtures (Mix) in the gills, digestive gland, and gonad of the Asian clam, Corbicula fluminea, assessing the oxidative stress responses, LDH activity, and neurotoxicity over 7, 14, 21, and 30 days. The results show that exposure to MPs and their mixtures with the lowest Cd concentration led to the activation of the first line of antioxidant defenses, especially SOD and CAT, in the gills, digestive gland, and gonads. An increase in GST activity was also observed in the gonads. However, the response of GST activity in the gills and digestive gland was opposite that observed in the gonads. Furthermore, LDH activity exhibited contrasting responses, increasing in the digestive gland and decreasing in the gills and gonads. Exposure to MPs induced AChE activity, which contradicts previous findings. The results provide novel insights into the biological responses occurring in different target organs and shed light on the effects of MPs and their mixtures on C. fluminea. Full article

The increased presence of resistant microorganisms in water promotes the need for supplementary measures to mitigate the water source’s contamination. Traditional treatments are inefficient in wastewater management at removing some emerging contaminants. Corbicula fluminea, an invasive species, can be used in the treatment due to their resistance and biofiltration capacity, working as a pest management strategy. In this study, this bivalve was used to promote the virus disinfection from the municipal wastewater treatment plant (MWTP) that enters (influent) and after the secondary treatment (effluent leaving the plant). JC virus, norovirus (GI, GII), and hepatitis A (HAV) were identified. C. fluminea promoted norovirus GI and GII removal after 72 h and a slight decrease in the JC virus concentration. These results prove the potential of this pest management approach to be used in virus removal. Furthermore, infectivity assays using mengovirus confirmed the correlation between the presence of the genome detected by PCR and the infectious virus particles. This highlights the potential of PCR as a reliable indicator of the infectious virus’s presence. However, such an infectivity assay proved that even when PCR results are undetectable, a reduced number of viruses may remain viable and able to infect susceptible cells in culture. Full article

(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. Full article

The Asian clam Corbicula fluminea is a native aquatic species in Eastern Asia and Africa but has become one of the ecologically and economically harmful invasive species in aquatic ecosystems in Europe, North America, and South America. Due to their natural characteristics as a hermaphroditic species with a high fecundity and dispersal capacity, Asian clams are extremely difficult to eradicate once they have infiltrated a waterbody. This is an emerging issue for states in the Northeastern United States, as Asian clams expand their range farther North due to climate change. There has been extensive research conducted to develop chemical treatments for reactively controlling invasive mollusc populations and proactively preventing their further spread. However, treatments are mostly targeted toward biofouling bivalves in industrial settings. A comprehensive review of Asian clam chemical treatments used in natural open-water systems was performed to evaluate molluscicides and identify the toxicity ranges of emerging treatments that maximize Asian clam mortality and minimize the negative impact on water quality and non-target species. The potential chemical applications in Asian clam control and management are summarized in this report to assist resource managers and practitioners in invasive Asian clam management. Full article