Freshwater Bivalve Corbicula Fluminea Research Articles

Toxicity of environmental and polystyrene plastic particles on the bivalve Corbicula fluminea: focus on the molecular responses.

Among aquatic organisms, filter feeders are particularly exposed to the ingestion of microplastics (MPs) and nanoplastics (NPs). The present study investigates the effect of environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized plastic debris collected in the Garonne River (France), and polystyrene NPs (PS NPs) on the freshwater bivalve Corbicula fluminea. Organisms were exposed to plastic particles at three concentrations: 0.008, 10, and 100 μg L-1 for 21 days. Gene expression measurements were conducted in gills and visceral mass at 7 and 21 days to assess the effects of plastic particles on different functions. Our results revealed: (i) an up-regulation of genes, mainly involved in endocytosis, oxidative stress, immunity, apoptosis, and neurotoxicity, at 7 days of exposure for almost all environmental plastic particles and at 21 days of exposure for PS NPs in the gills, (ii) PS NPs at the three concentrations tested and ENV MPs at 0.008 μg L-1 induced strong down-regulation of genes involved in detoxication, oxidative stress, immunity, apoptosis, and neurotoxicity at 7 days of exposure in the visceral mass whereas ENV MPs at 10 and 100 μg L-1 and all ENV NPs induced less pronounced effects, (iii) overall, PS NPs and ENV MPs 0.008 μg L-1 did not trigger the same effects as ENV MPs 10 and 100 μg L-1 and all ENV NPs, either in the gills or the visceral mass at 7 and 21 days of exposure. This study highlighted the need to use MPs and NPs sampled in the environment for future studies as their properties induce different effects at the molecular level to living organisms.

Fate, subcellular distribution and biological effects of rare earth elements in a freshwater bivalve under complex exposure

Rare earth elements (REE) are emerging contaminants due to their increased use in diverse applications including cutting-edge and green-technologies. Their environmental concerns and contradicting results concerning their biological effects require an extensive understanding of REE ecotoxicology. Thus, we have studied the fate, bioaccumulation and biological effects of three representative REE, neodymium (Nd), gadolinium (Gd) and ytterbium (Yb), individually and in mixture, using the freshwater bivalve Corbicula fluminea. The organisms were exposed for 96 h at 1 mg L−1 REE in the absence and presence of dissolved organic matter (DOM) reproducing an environmental contamination. Combined analysis of the fate, distribution and effects of REE at tissue and subcellular levels allowed a comprehensive understanding of their behaviour, which would help improving their environmental risk assessment. The bivalves accumulated significant concentrations of Nd, Gd and Yb, which were decreased in the presence of DOM likely due to the formation of REE-DOM complexes that reduced REE bioavailability. The accumulation of Nd, Gd and Yb differed between tissues, with gills > digestive gland ≥ rest of soft tissues > hemolymph. In the gills and in the digestive gland, Nd, Gd and Yb were mostly (>90 %) distributed among metal sensitive organelles, cellular debris and detoxified metal-rich granules. Gadolinium, Yb and especially Nd decreased lysosome size in the digestive gland and disturbed osmo- and iono-regulation of C. fluminea by decreasing Na concentrations in the hemolymph and Ca2+ ATPase activity in the gills. Individual and mixed Nd, Gd and Yb exhibited numerous similarities and some differences in terms of fate, accumulation and biological effects, possibly because they have common abiotic and biotic ligands but different affinities for the latter. In most cases, individual and mixed effects of Nd, Gd, Yb were similar suggesting that additivity approach is suitable for the environmental risk assessment of REE mixtures.

The Spatio-Temporal Distribution of the Freshwater Bivalves Corbicula fluminea and Dreissena polymorpha in the Lower Sector of the Danube River and the Danube Delta

The objective of this study is to provide an updated account of the distribution history of two invasive molluscs, Corbicula fluminea and Dreissena polymorpha, both in Europe and worldwide. In addition to this, the study also intends to review their ecological requirements to gain a better understanding of their invasive potential and distribution dynamics. Specifically, the study focuses on updating the distribution and ecological characteristics of these freshwater bivalves in the lower sector of the Danube River and the lakes of the Danube Delta. The purpose is to better understand their invasive and distribution dynamics and to develop effective measures to limit their spread in the future. To achieve this, environmental proxies such as sediment particle size and Total Organic Carbon (TOC) concentrations were used to assess their tolerances. However, the results did not show a significant correlation between the densities of these bivalves and the analyzed environmental parameters. Despite this, the species were found in high densities and formed well-developed benthic communities in some stations. The study contributes to the understanding of the invasiveness of these bivalve species and their distribution range dynamics. Nonetheless, further investigation is required to fully comprehend the role of environmental parameters in their distribution. The study covers the period between 2010 and 2020 and focuses on the lower Danube River sector and Danube Delta.

Feeding behavior, microcystin accumulation, biochemical response, and ultramicrostructure changes in edible freshwater bivalve Corbicula fluminea exposed to Microcystis aeruginosa.

As filter-feeders, bivalves naturally come into direct contact with microcystins (MCs) in eutrophic water bodies suffering from cyanobacteria blooms. To date, however, no studies have quantified the dynamics of microcystin accumulation and depuration in the edible freshwater bivalve Corbicula fluminea when exposed to dense bloom concentrations of Microcystis aeruginosa, while considering dynamic changes of biochemical indexes and feeding structure. In the present study, the bioaccumulation and detoxification of microcystin-LR (MC-LR) in C. fluminea were investigated. Our results showed that C. fluminea would graze equally efficiently on green algae and M. aeruginosa, irrespective of whether the M. aeruginosa strains were toxic or non-toxic. MCs could be accumulated and depurated by C. fluminea efficiently. In addition, linear and exposure time-dependent MC-LR accumulation patterns were observed in C. fluminea. Activities of biotransformation (glutathione S-transferase, GST) and antioxidant enzymes (superoxide dismutase, SOD, and catalase, CAT) and malondialdehyde (MDA) contents in various tissues of treated clams were stimulated by MCs in a tissue-specific manner. Our findings indicated that C. fluminea hepatopancreas was the primary target organ for MC-LR detoxification processes, as evidenced by a significant increase in GST activity. Besides, gills and mantle were more sensitive than the other tissues to oxidative stress in the initial microcystin exposure period with a significant increase in SOD activity. The scanning electron microscopy (SEM) observations revealed that the lateral cilia in the gill aperture were well developed during the MCs exposure period, which could perform the filter-feeding function instead of the damaged frontal cilium. This study provides insight into the possible tolerance of C. fluminea exposed to dense bloom concentrations of M. aeruginosa.

Invertebrate Species for the Bioavailability and Accumulation Assessment of Manufactured Polymer-Based Nano- and Microplastics.

Bioaccumulation tests with invertebrates have recently been discussed as a suitable alternative to bioaccumulation tests with metal- or metal oxide-based nanoparticles in fish for regulatory assessment. In the present study, as a first step, we investigated the suitability of three invertebrate species for bioaccumulation tests with nano- and microplastics. In a laboratory approach the freshwater bivalve Corbicula fluminea, the freshwater amphipod Hyalella azteca, and the terrestrial isopod Porcellio scaber were exposed to fluorescently labeled nano- and microplastics to evaluate their suitability to estimate the bioavailability and bioaccumulation of these test items. No bioaccumulation was observed in H. azteca or P. scaber. In contrast, the measurement of the relative fluorescence of the test items in the soft tissue and the feces of the filter-feeding bivalve allowed us to derive data that may be useful for the regulatory bioaccumulation assessment of manufactured nano- and microplastics. The developed measurement method using fluorescence represents a time-efficient and cost-effective analytical method for manufactured nano- and microplastics in laboratory studies for regulatory assessment. Environ Toxicol Chem 2022;41:961-974. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Heavy Metal Determination of Bivalves in Cagayan Valley, Philippines

Level of heavy metals like Cadmium (Cd) and Lead (Pb) in bivalves has been intensively studied during recent years as these hazardous substances could be accumulated in the biota and has been a hot issue in marine environmental studies. By consuming the shellfish, risk of bivalve related diseases may increase. And this shellfish poisoning is a concern to public health. This research study aims to determine if the Bivalves in Cagayan Valley, Philippines is safe to consume. The Freshwater clam (Corbicula fluminea) and the Marine mussel (Mytilus edulis) in Cagayan Valley, Philippines was collected for this study. The byssus and shells were removed, leaving only soft tissues to be used for the analysis and they were categorized into two. Graphite Furnace- Atomic Absorption Spectrophotometer (GFAAS) was used to determine the concentrations of Cadmium (Cd) and Lead (Pb). The results showed that the Freshwater bivalves Corbicula fluminea has a concentration 0.006 μg/g of Lead (Pb) and a concentration 0.016 μg/g. of Cadmium (Cd) while for Marine bivalves Mytilus edulis, the concentration of Pb was 0.011 μg/g and the concentration of Cd levels was 0.015 μg/g. The test results showed that the heavy metals, lead, and cadmium, were at low levels when referred to guidelines on heavy metals for food safety by different countries, particularly Malaysia. Thus, the results that were found were quite lower and there are no health risks to the people when consuming these bivalves collected from the province of Cagayan. Based on the results of the study conducted, the researchers recommend using different bivalve species to know the levels of heavy metals on bivalve species, investigate lead and cadmium heavy metals concentrations of one species collected in different areas/locations in Cagayan Valley and investigate the lead and cadmium heavy metal concentration of different bivalves in a regular basis i.e., monthly, or quarterly for at least 1 year.

Biota-sediment metal accumulation and human health risk assessment of freshwater bivalve Corbicula fluminea in Dongting Lake, China.

In this study, we analyzed the concentrations of metals in sediments and Corbicula fluminea in China's Dongting Lake to assess the suitability of C. fluminea as an effective biomonitor of metal contamination in sediments and food safety. We analyzed the biota-accumulation capacity by calculating the biota-sediment accumulation factor (BSAF) and assessed the potential human health risk of metals exposure via consumption of C. fluminea using the target hazard quotient (THQ) and total target hazard quotient (TTHQ). The results showed that the average concentrations of As (31.93mgkg-1), Cd (5.54mgkg-1), Cr (105.50mgkg-1), Cu (32.53mgkg-1), and Zn (207.89mgkg-1) in sediments were higher than their respective standard set by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China. The sediment metals, which were mainly anthropogenic in origin, were at high levels and pose a relatively high ecological risk. Cadium (Cd) showed very high potential ecological risk levels and should be included in the prior pollutants list in the studied area. The mean levels of As (0.81mgkg-1) in C. fluminea were 1.62-times higher than that set by the National Health Commission of the People's Republic of China. BSAF values of the soft tissues of C. fluminea were between 0.05 and 2.14, with higher values for Cu (2.14), Cd (1.77), Zn (1.60), and Ni (1.27). Soft tissues of C. fluminea were able to reflect spatial differences in Sr within sediments around Dongting Lake. The results indicated that C. fluminea could be an potential biomonitor for sediment metals assessment in biomonitoring programs, especially for Cu, Cd, Zn, Ni, and Sr. The mean values for THQ and TTHQ of all the analyzed metals were below 1.0, indicating that the intake of metals via comsumption of C. fluminea does not result in an appreciable risk to human health.

Bioaccumulation dynamics and gene regulation in a freshwater bivalve after aqueous and dietary exposures to gold nanoparticles and ionic gold.

Gold nanoparticles (AuNPs) are being developed and produced for a wide variety of industrial and biomedical applications, which raises the concern about their release and potential effects in the environment. In this study, we aim to assess the effects of PEGylated AuNPs and ionic gold on the freshwater bivalve Corbicula fluminea. As NP bioavailability is conditioned by many factors of variability, we focused on the determination of biodynamic parameters which control AuNP uptake and elimination in bivalves. Three experiments were conducted: (1) a waterborne exposure (0-24mg/L for AuNPs and 0-12mg/L for ionic gold), (2) a dietborne exposure (0-48mg/L for AuNPs and 0-24mg/L for ionic gold), and (3) an elimination phase (after waterborne exposure to 12mg/L for AuNPs and 24mg/L for ionic gold), to calculate rate constants for uptake from water(kuw), from food (kuf), and for the physiological elimination (ke) for AuNPs and AuCl(OH)3-. Jointly, the relative expression of several genes was investigated in the hemolymph cells to relate AuNPs and gold ion exposures to detoxification, oxidative stress, immune, and apoptosis responses in C. fluminea. Results show that kuw and kuf were around 10 and 30 times higher for AuNPs compared to AuCl(OH)3-, respectively. The ke was also faster in clams exposed to AuNPs meaning that they also had greater excretion capacities in comparison to gold ions. Water seems to be the main exposure pathway for C. fluminea according to kuw and kuf values for AuNPs and AuCl(OH)3- (kuw = 0.28 and 0.03, kuf = 0.009 and 0.001, respectively). The gene analyses pointed out important responses against oxidative stress, strong activations of genes of the immunity, and apoptosis after the waterborne exposure to AuNPs and to a lesser extent after exposure to gold ions. Very few responses were observed after the dietary exposure to both forms of gold, probably due to valve closure in response to contamination. While some studies suggest that the toxicity of nanoparticles may come from the release of metal ions, our results showed that the AuNPs we used were very stable (less than 1% of ion release) and generated more effects at the gene level than ionic gold. Therefore these results highlight the strong potential of toxicity of AuNPs compared to ionic gold and raise new concerns about the toxicity inherent to NPs in the environment.

Effects of microplastics and mercury in the freshwater bivalve Corbicula fluminea (Müller, 1774): Filtration rate, biochemical biomarkers and mercury bioconcentration

The main objectives of this study were to investigate the effects of a mixture of microplastics and mercury on Corbicula fluminea, the post-exposure recovery, and the potential of microplastics to influence the bioconcentration of mercury by this species. Bivalves were collected in the field and acclimated to laboratory conditions for 14 days. Then, a 14-day bioassay was carried out. Bivalves were exposed for 8 days to clean medium (control), microplastics (0.13 mg/L), mercury (30 µg/L) and to a mixture (same concentrations) of both substances. The post-exposure recovery was investigated through 6 additional days in clean medium. After 8 and 14 days, the following endpoints were analysed: the post-exposure filtration rate (FR); the activity of cholinesterase enzymes (ChE), NADP-dependent isocitrate dehydrogenase (IDH), octopine dehydrogenase, catalase, glutathione reductase, glutathione peroxidase and glutathione S-transferases (GST), and the levels of lipid peroxidation (LPO). After 8 days of exposure to mercury, the bioconcentration factors (BCF) were 55 in bivalves exposed to the metal alone and 25 in bivalves exposed to the mixture. Thus, microplastics reduced the bioconcentration of mercury by C. fluminea. Bivalves exposed to microplastics, mercury or to the mixture had significantly (p ≤ 0.05) decreased FR and increased LPO levels, indicating fitness reduction and lipid oxidative damage. In addition, bivalves exposed to microplastics alone had significant (p ≤ 0.05) reduction of adductor muscle ChE activity, indicating neurotoxicity. Moreover, bivalves exposed to mercury alone had significantly (p ≤ 0.05) inhibited IDH activity, suggesting alterations in cellular energy production. Antagonism between microplastics and mercury in FR, ChE activity, GST activity and LPO levels was found. Six days of post-exposure recovery in clean medium was not enough to totally reverse the toxic effects induced by the substances nor to eliminate completely the mercury from the bivalve’s body. These findings have implications to animal, ecosystem and human health.

Toxicity effects of silver nanoparticles on the freshwater bivalve Corbicula fluminea

Toxicity effects of silver nanoparticles (AgNPs) on the freshwater bivalve Corbicula fluminea (C. fluminea) were investigated through experiments. In this study, C. fluminea promoted the sedimentation of AgNPs and affected the fate and transformation of AgNPs. A series of biomarkers of C. fluminea in vivo were evaluated after 14 days exposure to various doses (0–2 mg L−1) of polyvinyl pyrrolidone (PVP) coated AgNPs. The levels of antioxidants increased obviously in 2 mg L−1 AgNPs treatments to protect C. fluminea from oxidative damage. Glutathione peroxidase (GPx) and glutathione (GSH) played important roles in tissues detoxification in 0.1 and 0.5 mg L−1 exposure, respectively. The biological behaviors (feeding rate, ammonia excretion rate) were inhibited at 0.1 mg L−1, inducted at 0.5 mg L−1, and inhibited again at 2 mg L-1 AgNPs, which indicated that AgNPs influenced the physiological metabolism of C. fluminea. Ag contents in tissue and shell of C. fluminea were much higher than blank groups. In addition, in vivo tissues were more sensitive to low AgNPs concentration compared with shells, indicating that C. fluminea could be used as a good indicator for AgNPs freshwater pollution. No Ag was detected in feces probably implying that nanoparticles had long gut retention time in C. fluminea. Overall, this study reveals the interactions between AgNPs and C. fluminea and provides important implications about the fate and toxicity of AgNPs in natural aquatic environment.

Genotoxicity and physiological effects of CeO2 NPs on a freshwater bivalve (Corbicula fluminea)

The rapid development of nanotechnology and the increased use of nanomaterials in products used in everyday life have raised the question of the potential release of nanoparticles into the aquatic environment. Their fate and effects in natural ecosystems are not currently well understood but harmful effects of nanoparticles have been demonstrated at low concentrations on some freshwater and marine species. Cerium dioxide nanoparticles (CeO2 NPs) are produced in large quantities and used in products in many different fields, such as automotives or optics. Because of their widespread use in daily products, CeO2 NPs are included in the OECD priority list of manufactured nanomaterials for human and environmental assessment. Indeed some studies have been conducted to assay various enzymatic biomarkers, which showed the CeO2 NPs potential to modify anti-oxidative defenses and cellular membrane stability. Nevertheless, only a few studies were performed on their genotoxic potential. The aim of this work was to evaluate the genotoxic and physiological effects of CeO2 NPs on a widespread freshwater bivalve Corbicula fluminea by using comet assay and a multi-enzymatic biomarker approach. Exposure to two CeO2 NP concentrations during a short term experiment (6 days) was set up. The first one (10 μg/L) was chosen in order to work with low but measurable concentrations whereas the second one was ten times higher (100 μg CeO2 NPs/L). DNA damage was significantly more pronounced compared with control for both concentrations tested as early as two days of exposure and seemed to increase with time. Some enzymatic biomarkers of anti-oxidative defenses (total antioxidant capacity, catalase activity), anti-toxic mechanisms (glutathione-S-transferase activity, caspase-3 activity) or metabolism (lactate dehydrogenase activity) tended to increase after 6 days of exposure but only the induction of caspase pathway and DNA damages appeared significant for exposed organisms. In this study, time and concentration effects of CeO2 NPs were highlighted by coupling genotoxic and cellular biomarker assessments.

Lead accumulation (adsorption and absorption) by the freshwater bivalve Corbicula fluminea in sediments contaminated by TiO2 nanoparticles

With the increasing production and applications of TiO2 nanoparticles (NPs), their presence in aquatic environments, especially in sediments, will inevitably increase over time. Most studies investigating the influence of TiO2 NPs on the bioaccumulation of co-existing contaminants have focused on the aqueous phase; however, few have examined the sediment phase, which contains more TiO2 NPs and contaminants. We investigated the effects of TiO2 NPs on Pb accumulation by Corbicula fluminea in sediments, and explored extracellular and intracellular Pb concentrations in the various soft tissues of the bivalve. Pb was spiked with 50 mg/kg in sediment and TiO2 NPs/sediments ratios were within the range 0.2–3.0%. The results showed that TiO2 NPs presented larger adsorption capacity and affinity to Pb ions than the sediments. In addition, the large adsorption capacity of TiO2 NPs and the strong adsorption affinity to Pb ions caused part of the Pb ions released from sediments to aqueous phase were re-adsorbed by TiO2 NPs in sediments. The concentration of TiO2 NPs in C. fluminea tissues significantly increased with increasing TiO2 NP content in sediments, following the order: gill > mantle > foot > visceral mass, which differed from the results found in the aqueous phase. In addition, the proportions of extracellular and intracellular Pb concentrations changed significantly in all the tissues as a result of TiO2 NP contamination of sediments. TiO2 NPs promote increased extracellular Pb in foot, mantle, and gill tissues, and increased intracellular Pb in the visceral mass. These results may be beneficial to more scientifically evaluate and predict the environmental risks of TiO2 NPs to benthic organisms in sediments contaminated by heavy metals.

Bioavailability and toxicity of metals from a contaminated sediment by acid mine drainage: linking exposure–response relationships of the freshwater bivalve Corbicula fluminea to contaminated sediment

Streams and rivers strongly affected by acid mine drainage (AMD) have legal vacuum in terms of assessing the water toxicity, since the use of conventional environmental quality biomarkers is not possible due to the absence of macroinvertebrate organisms. The Asian clam Corbicula fluminea has been widely used as a biomonitor of metal contamination by AMD in freshwater systems. However, these clams are considered an invasive species in Spain and the transplantation in the field study is not allowed by the Environmental Protection Agency. To evaluate the use of the freshwater bivalve C. fluminea as a potential biomonitor for sediments contaminated by AMD, the metal bioavailability and toxicity were investigated in laboratory by exposure of clams to polluted sediments for 14days. The studied sediments were classified as slightly contaminated with As, Cr, and Ni; moderately contaminated with Co; considerably contaminated with Pb; and heavily contaminated with Cd, Zn, and specially Cu, being reported as very toxic to Microtox. On the fourth day of the exposure, the clams exhibited an increase in concentration of Ga, Ba, Sb, and Bi (more than 100%), followed by Co, Ni, and Pb (more than 60%). After the fourth day, a decrease in concentration was observed for almost all metals studied except Ni. An allometric function was used to determine the relationship between the increases in metal concentration in soft tissue and the increasing bioavailable metal concentrations in sediments.

Biomarkers in the freshwater bivalve Corbicula fluminea confined downstream a domestic landfill leachate discharge.

Landfills represent a severe environmental problem mainly due to the generation of leachates, and this study aimed to evaluate sublethal effects of a domestic landfill leachate in the freshwater bivalve Corbicula fluminea. Clams were submitted to in situ tests along a stream, at three sites, representing increasing distances from the leachate discharge (Pq1, Pq2, and Pq3), for 1, 5, and 15days. The following biomarkers were analyzed in the gills and digestive glands: 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities, multixenobiotic resistance mechanism (MXR), total antioxidant capacity (TAC), reactive oxygen species (ROS), and lipid peroxidation (LPO). Metallothionein (MT) content was determined in the gills and DNA damage in hemocytes. The mortality rate of animals during in situ tests was reduced as the distance from the leachate discharge source increased. On the other hand, biomarker results showed sublethal effects on C. fluminea confined at all sites of PqS. GST, TAC, ROS, and DNA damage were the most significant biomarkers for this species and should be considered for future monitoring and assessment of freshwater environments located in landfill areas.

Mechanisms of cadmium accumulation (adsorption and absorption) by the freshwater bivalve Corbicula fluminea under hydrodynamic conditions

Many heavy metals in sediments and water have potential adverse effects on aquatic organisms such as Corbicula fluminea (O.F. Müller, 1774), a bivalve species frequently used as a biomonitor for metal pollution. Studies over the past decades examining the heavy metal uptake by C. fluminea, very few has investigated the effect of hydrodynamic conditions on accumulation of heavy metal by C. fluminea. Therefore, in this study, to investigate the mechanism of intracellular and extracellular accumulation of metal, individuals of C. fluminea were exposed to cadmium (Cd)-treated water under three different hydrodynamic conditions. These included exposures in two set ups: three rates of rotation (500, 350, 200 r/min) in beakers for 10 days, and then exposure to Cd-treated sediment under two naturally turbulent water conditions (14 cm/s and 3.2 cm/s) in experimental flumes for 23 days. Hydrodynamic force increased the burrowing rate but decreased the activity of C. fluminea. After 10 days of exposure, the extracellular concentrations of Cd in the tissues of C. fluminea in the sand group were significantly higher than that in the gravel groups. The intracellular and extracellular concentrations of Cd in the tissues of C. fluminea dramatically increased in the Cd-treated sediment test. Moreover, the concentration of the extracellular Cd adsorbed on the tissues of C. fluminea in the 14 cm/s and 3.2 cm/s groups was significantly higher than that in the control group, whereas the effect of hydrodynamic force on absorption of Cd by C. fluminea was not obvious. These results suggest that hydrodynamic condition plays an important role in extracellular accumulation of Cd by C. fluminea. In future study, when using C. fluminea to assess Cd pollution in aquatic environment, extracellular Cd adsorbed on the tissue should be removed to avoid the influence of hydrodynamics.

Rare earth elements in the aragonitic shell of freshwater mussel Corbicula fluminea and the bioavailability of anthropogenic lanthanum, samarium and gadolinium in river water

High-technology metals — such as the rare earth elements (REE) — have become emerging contaminants in the hydrosphere, yet little is known about their bioavailability. The Rhine River and the Weser River in Germany are two prime examples of rivers that are subjected to anthropogenic REE input. While both rivers carry significant loads of anthropogenic Gd, originating from contrast agents used for magnetic resonance imaging, the Rhine River also carries large amounts of anthropogenic La and lately Sm which are discharged into the river from an industrial point source.Here, we assess the bioavailability of these anthropogenic microcontaminants in these rivers by analyzing the aragonitic shells of the freshwater bivalve Corbicula fluminea. Concentrations of purely geogenic REE in shells of comparable size cover a wide range of about one order of magnitude between different sampling sites. At a given sampling site, geogenic REE concentrations depend on shell size, i.e. mussel age.Although both rivers show large positive Gd anomalies in their dissolved loads, no anomalous enrichment of Gd relative to the geogenic REE can be observed in any of the analyzed shells. This indicates that the speciations of geogenic and anthropogenic Gd in the river water differ from each other and that the geogenic, but not the anthropogenic Gd is incorporated into the shells. In contrast, all shells sampled at sites downstream of the industrial point source of anthropogenic La and Sm in the Rhine River show positive La and Sm anomalies, revealing that these anthropogenic REE are bioavailable. Only little is known about the effects of long-term exposure to dissolved REE and their general ecotoxicity, but considering that anthropogenic Gd and even La have already been identified in German tap water and that anthropogenic La and Sm are bioavailable, this should be monitored and investigated further.

Cadmium Accumulation and Metallothionein Response in the Freshwater Bivalve Corbicula fluminea Under Hydrodynamic Conditions.

Freshwater bivalves such as Corbicula fluminea (Müller) are useful biomonitors for cadmium pollution because they absorb heavy metals and accumulate them in their tissues. We exposed C. fluminea in the laboratory to natural and cadmium (Cd)-spiked sediments below flowing water in order to evaluate the organisms' Cd accumulation and metallothionein (MT) response under hydrodynamic conditions. The accumulation of Cd and the induction of MT in C. fluminea were determined at 0, 1, 3, 6, 10, 16, and 23days. Hydrodynamic conditions, represented by a water flow rate of 14 or 3.2cm/s, increased Cd accumulation in the visceral mass, gill, foot, and mantle of C. fluminea in the first 3 or 6days in the natural sediment. Cd concentrations in the C. fluminea tissues kept increasing over time in the three treatments, and significant differences were observed in Cd accumulation after 6 (visceral mass), 10 (foot) and 16 (gill and mantle) days among the three groups. The MT concentrations were barely affected by hydrodynamic conditions and were significantly linearly related to the Cd concentration in the visceral mass in the natural sediment and binomially related to it in the Cd-spiked sediment. Hydrodynamic conditions enhanced the accumulation of Cd in the soft tissues of C. fluminea, especially in the Cd-spiked sediment, but stronger hydrodynamic forces did not increase Cd accumulation. MT may be considered an indicator for Cd accumulation in C. fluminea under hydrodynamic conditions, but only when the Cd concentrations in the tissue remain below the toxic threshold values.

Bioavailability of cadmium and biochemical responses on the freshwater bivalve Corbicula fluminea – the role of TiO2 nanoparticles

The increasing and widespread applications of TiO2 engineered nanoparticles (nTiO2) led to the release of these materials into aquatic environments and consequently a change on the assessment of the environmental risk of trace metals. In this work, the role of two commercial nTiO2 with distinct crystalline phases and sizes (nTiO2-P25: 80% anatase+20% rutile, d=20nm; nTiO2-NA: 100% anatase, d=5nm; 0.1 and 1.0mgL−1) on Cd (112μgL−1) speciation, biouptake and toxicity for the freshwater bivalve Corbicula fluminea was evaluated. The electroanalytical technique ‘absence of gradients and Nernstian equilibrium stripping (AGNES)’ was used to quantify the free Cd concentrations in the exposure medium in presence of both particles. Despite ca. 30–40% decrease of free Cd in the medium in presence of nTiO2, Cd uptake by C. fluminea was similar in the absence and presence of either of the particles. Superoxide dismutase and glutathione-S-transferase activities remained unchanged for Cd in absence and presence of nTiO2, whereas a significant increase of the catalase activity was obtained at the third day for Cd in presence of both nTiO2. Despite lipid peroxidation data shows that the presence of both nTiO2 seems to exert cells damage, a more quantitative description is not possible with the obtained data. The lack of clear-cut responses by the studied biomarkers, even when only in presence of Cd, do not allow insights into the effect of the presence of nTiO2 on the Cd toxicity to the bivalves. Notwithstanding, morphological changes in the digestive gland were clearly obtained in the presence of Cd, nTiO2 and Cd+nTiO2 indicating an inflammatory response.

Detoxification and recovery capacities of Corbicula fluminea after an industrial metal contamination (Cd and Zn): A one-year depuration experiment

This study aimed to assess the recovery capacity of the freshwater bivalve Corbicula fluminea subjected to industrial metal discharges (Cd, Zn). After a 24-day exposure in a metal-contaminated river, bivalves were transferred and maintained in the laboratory for one year under metal-free conditions. Metal accumulation, metallothionein production and genetic expressions of genes involved in metal stress were studied. Results demonstrated the high persistence of Cd in tissues (only 73% eliminated after 365 days) whereas Zn was rapidly depurated. The Cd half-life was estimated around 240 days. Metallothioneins were strongly induced within the 28 first days of decontamination, then decreased by 45% after 365 days. The metal exposure of bivalves led to a significant gene induction. After 28 days, most of the genes were no longer overexpressed, suggesting that the bivalves may withstand small amounts of non-essential metals in their tissues without showing signs of detrimental effects on the tested genes.

The Asian invasive freshwater clam Corbicula fluminea as prey of two native waterbirds in South-eastern Brazil

The invasive Asiatic freshwater bivalve Corbicula fluminea is regarded as a pest in several countries including Brazil. Two water birds native to South America, the limpkin Aramus guarauna and the common gallinule Gallinula galeata, are herein recorded preying on C. fluminea in a pond of an urban park in South-eastern Brazil. The exotic clam is becoming increasingly common in the diet of both these water birds. This trend is likely due to its increasing population and the consequent rarity of the habitual prey (apple snails and native clams) for the mollusc-specialised limpkin, besides being an accessible animal protein source for the omnivorous gallinule.