Search

In the last decades the use of rare earth elements (REEs) increased exponentially, including Terbium (Tb) which has been widely used in newly developed electronic devices. Also, the production and application of nanoparticles has been growing, being Carbon Nanotubes (CNTs) among the most commonly used. Accompanying such development patterns, emissions towards the aquatic environments are highly probable, with scarce information regarding the potential toxicity of these pollutants to inhabiting species, especially considering their mixture. In the present study the effects of Tb and CNTs exposure (acting alone or as a mixture) on native and invasive clams' species (Ruditapes decussatus and Ruditapes philippinarum, respectively) were evaluated, assessing clams' accumulation and metabolic capacities, oxidative status as well neurotoxic impacts. Results obtained after a 28-days exposure period showed that the accumulation of Tb in both species was not affected by the presence of the CNTs and similar Tb concentrations were found in both species. The effects caused by Tb and CNTs, acting alone or as a mixture induced greater alterations in R. philippinarum antioxidant capacity in comparison to native R. decussatus, but no cellular damages were observed in both species. Nevertheless, although metabolic impairment was only observed in clams exposed to Tb, loss of redox balance and neurotoxicity were evidenced by both species regardless the exposure treatment. These findings highlight the potential impacts caused by CNTs and Tb, which may affect clams' normal physiological functioning, impairing their reproduction and growth capacities. The obtained results point out the need for further investigation considering the mixture of pollutants., Competing Interests: Declaration of competing interest The Authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or nonfinancial /interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In the marine environment, organisms are exposed to a high and increasing number of different contaminants that can interact among them. In addition, abiotic factors can change the dynamics between contaminants and organisms, thus increasing or even decreasing the toxic effect of a particular compound. In this study, the effects of caffeine (CAF) and functionalized multi-walled carbon nanotubes (f-MWCNTs) induced in the clam Ruditapes philippinarum were evaluated, acting alone and in combination (MIX), under two temperature levels (18 and 21 °C). To assess the impact of such compounds, their interaction and the possible influence of temperature, biochemical and histopathological markers were investigated. The effects of f-MWCNTs and caffeine appear to be clearly negative at the control temperature, with lower protein content in contaminated clams and a significant decrease in their metabolism when both pollutants were acting in combination. Also, at control temperature, clams exposed to pollutants showed increased antioxidant capacity, especially when caffeine was acting alone, although cellular damages were still observed at CAF and f-MWCNTs treatments. Increased biotransformation capacity at 18 °C and MIX treatment may explain lower caffeine concentration observed. At increased temperature differences among treatments were not so evident as at 18 °C, with a similar biological pattern among contaminated and control clams. Higher caffeine accumulation at MIX treatment under warming conditions may result from clams' inefficient biotransformation capacity when exposed to increased temperatures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nowadays, multi-walled carbon nanotubes are considered to be emerging contaminants and their impact in ecosystem has drawn special research attention, while other contaminants, such as caffeine, have more coverage in literature. Despite this, the effects of a combination of the two has yet to be evaluated, especially considering predicted temperature rise. In the present study a typical bioindicator species for marine environment, the clam Ruditapes decussatus, and classical tools, such as biomarkers and histopathological indices, were used to shed light on the species' response to these contaminants, under actual and predicted warming scenarios. The results obtained showed that both contaminants have a harmful effect at tissue level, as shown by higher histopathological index, especially in digestive tubules. Temperatures seemed to induce greater biochemical impacts than caffeine (CAF) and -COOH functionalized multi-walled carbon nanotubes (f-MWCNTs) when acting alone, namely in terms of antioxidant defences and energy reserves content, which were exacerbated when both contaminants were acting in combination (MIX treatment). Overall, the present findings highlight the complex response of clams to both pollutants, evidencing the role of temperature on clams' sensitivity, especially to mixture of pollutants., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Ficopomatus enigmaticus was adopted as model species for ecotoxicological bioassay, with its larval development as endpoint. Two different populations of the same species, collected in areas far from each other (Mediterranean Sea and Atlantic Ocean), were exposed to multi-walled carbon nanotubes, a class of emerging pollutants with a constantly increasing relevance in the landscape of nanomaterials production. Moreover, a molecular analysis based on Cyt b amplification and sequencing, was carried out to confirm that both populations belong to the same species. The aim of the present work was to strengthen existing results about F. enigmaticus relevance in ecotoxicological bioassays, adding the variable of population effect. For both populations the concentration-response curve of effect at different toxicant concentrations was similar and, at certain concentrations, overlapping, confirming the ecological relevance of the assay. These results posed an interesting acceptance on the introduction of this species as model in ecotoxicological bioassay scenery, underlining the relevance of a widespread wild species to compare effects of chemicals and environmental samples over large distances using the same bioassay., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Although the increased production of nanoparticles (NPs) has raised extensive concerns about the potential toxic effects on aquatic organisms, as well as the increasing evidences which documented the impact of ocean acidification (OA) on the physiology and fitness of marine invertebrates, limited number of studies reported their combined toxic effects. For these reasons, in the present study, we investigated the physiological and biochemical responses of one of the most economically important bivalve species in the World, the Manila clam Ruditapes philippinarum, after the exposure to an environmnetally relevant concentration of carboxylated carbon nanotubes and predicted OA conditions. The results showed that the organisms were not only susceptible to NPs but also to seawater acidification. Different responses between low pH and NPs for most tested biomarkers were observed, both in terms of physiological (respiration rate) and biochemical responses (metabolic capacity, oxitative status and neurotoxicity). Acidified pH significantly decreased the respiration rate and metabolism and increased the energy reserves consumption. Moreover, increase of the oxidative damage was also detected under this condition confirming that the mechanism of enhanced toxicity in the organisms should be attributed to lower aggregation state with more suspended NPs in acidified seawater, indicating that seawater acidification significantly influenced the impact of the used NPs in the exposed organisms.

Ocean acidification events are recognized as important drivers of change in biological systems. Particularly, the impacts of acidification are more severe in estuarine systems than in surface ocean due to their shallowness, low buffering capacity, low salinity and high organic matter from land drainage. Moreover, because they are transitional areas, estuaries can be seriously impacted by a vast number of anthropogenic activities and in the last decades, carbon nanomaterials (CNMs) are considered as emerging contaminants in these ecosystems. Considering all these evidences, chronic experiment was carried out, trying to understand the possible alteration on the chemical behaviour of two different CNMs (functionalized and pristine) in predicted climate change scenarios and consequently, how these alterations could modify the sensitivity of one the most common marine and estuarine organisms (the polychaeta Hediste diversicolor) assessing a set of biomarkers related to polychaetes oxidative status as well as the metabolic performance and neurotoxicity. Our results demonstrated that all enzymes worked together to counteract seawater acidification and CNMs, however oxidative stress in the exposed polychaetes to both CNMs, especially under ocean acidification conditions, was enhanced. In fact, although the antioxidant enzymes tried to cope as compensatory response of cellular defense systems against oxidative stress, the synergistic interactive effects of pH and functionalized CNMs indicated that acidified pH significantly increased the oxidative damage (in terms of lipid peroxidation) in the cotaminated organisms. Different responses were observed in organisms submitted to pristine CNMs under pH control, where the lipid peroxidation did not increase along with the increasing exposure concentrations. The present results further demonstrated neurotoxicity caused by both CNMs, especially noticeable at acidified conditions. The mechanism of enhanced toxicity could be attributed to slighter aggregation and more suspended NMs in acidified seawater (as demonstrated by the DLS analysis). Therefore, ocean acidification may cause a higher risk of CNMs to marine ecosystems., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The widespread use of Carbon nanotubes (CNTs) has been increasing exponentially, leading to a significant potential release into the environment. Nevertheless, the toxic effects of CNTs in natural aquatic systems are related to their ability to interact with abiotic compounds. Considering that salinity variations are one of the main challenges in the environment and thus may influence the behavior and toxicity of CNTs, a laboratory experiment was performed exposing the tube-building polychaete Diopatra neapolitana (Delle Chiaje 1841) for 28 days to pristine multi-walled carbon nanotube (MWCNTs) and carboxylated MWCNTs, maintained at control salinity 28 and low salinity 21. An innovative approach based on thermogravimetric analysis (TGA) was adopted for the first time to assess the presence of MWCNTs aggregates in the organisms. Both CNTs generated toxic impacts in terms of regenerative capacity, energy reserves and metabolic capacity as well as oxidative and neuro status, however greater toxic impacts were observed in polychaetes exposed to carboxylated MWCNTs. Moreover, both CNTs maintained under control salinity (28) generated higher toxic impacts in the polychaetes compared to individuals maintained under low salinity (21), indicating that exposed polychaetes tend to be more sensitive to the alteration induced by salinity variations on the chemical behavior of both MWCNTs in comparison to salt stress., (Copyright © 2019 Elsevier Inc. All rights reserved.)

With the increased production and research on nanoparticles, the presence of carbon nanotubes (CNTs) in aquatic systems is very likely to increase. Although it has been shown that CNTs may cause toxicity in marine organisms, to our knowledge, the possible impacts under global temperature increase is still unknown. For this reason, biochemical and physiological impacts induced in Mytilus galloprovincialis due to the presence of functionalized multi-walled CNTs (f-MWCNTs) and increased temperature were investigated in the present study. The mussels exposed to increased temperature alone presented higher metabolic capacity and expenditure of glycogen as an energy resource to fuel up defense mechanisms and thus preventing oxidative damage. Contrarily, organisms exposed to f-MWCNTs alone seemed not stressed enough to demonstrate differences in the metabolism capacity. Furthermore, f-MWCNTs seemed not able to significantly activate their antioxidant and biotransformation enzymes, which in turn may led to oxidative damage in the cells especially when organisms were exposed to a warmer temperature. In fact, at higher temperature, the antioxidant response of organisms exposed to f-MWCNTs was not effective and oxidative damage levels were observed. Nevertheless, no additive or synergetic effects were observed when mussels were exposed to both stressors simultaneously., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In recent years, oxidative stress has been recognized as one of the most common effects of nanoparticles in different organisms. Ficopomatus enigmaticus (Fauvel, 1923), a member of a large family of serpulidae polychates, is an important encrusting organism in a diverse set of marine habitats, from harbours to coral reefs. This species has been previously studied for ecotoxicological purposes, despite the lack of reported studies on this species biochemical response after exposure to different pollutants. For these reasons, and for the first time, a set of biomarkers related to oxidative status were assessed in polychaetes after 28 days of exposure. Furthermore, polychaetes metabolic performance and potential neurotoxicity were investigated. Results clearly demonstrated induced toxicity in the filter-feeder polychaetes after exposure to nanoparticles. Indeed, CNTs altered the biochemical and physiological status of F. enigmaticus, both in terms of energy reserves (reduction of protein and glycogen contents), oxidative status (expressed as damage in cell function such as protein carbonyl content and lipid peroxidation) and activation of antioxidant enzymes defences (Glutathione reductase, Catalase, Glutathione peroxidase and Glutathione S-transferases activities). The present study showed for the first time that this species can be used as a model organism for nanoparticle toxicology., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Salinity plays a fundamental role in naturally fluctuating environments such as estuaries influencing physiological and biochemical performance of inhabiting biota. Moreover salinity is considered one of the main factors influencing nanoparticles' stability. Thus, the aim of the present paper was to show the impacts induced by different salinities (control-28 and 21) on the chemical behavior of water dispersible multi-walled carbon nanotube (MWCNTs-COOH) and the consequent toxicity in the common ragworm Hediste diversicolor, after long term exposure. Results showed a concentration-dependent toxicity in terms of energy reserves and metabolism, oxidative status and neurotoxicity. In addition, under low salinity (21), the toxicity of the carbon NMs was similar to the impacts measured under control (28), although under salinity 28 the concentrations of MWCNTs-COOH used generated greater alterations in LPO levels and antioxidant enzymes (SOD and GPx). These results demonstrate that higher salinity caused the formation of large-size aggregates, which increased the chance of physical retention, such as gravitational sedimentation, interception and straining of f-MWCNTs generating higher cell injuries than the impacts induced in polychaetes sensitivity to these contaminates due to low salinity., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Although an increasing number of studies have been published on the effects of emergent pollutants such as carbon nanoparticles, there is still scarce information on the impact of these contaminants on marine organisms when acting in combination with classical pollutants such as meta(loid)s. The present study evaluated the impacts of Arsenic and Multi-Walled Carbon Nanotubes (MWCNTs) in the clam Ruditapes philippinarum, assessing the effects induced when both contaminants were acting individually (As, NP) and as a mixture (As + NP). Metabolic capacity (electron transport system activity), oxidative stress (antioxidant and biotransformation enzymes activity and cellular damage) and neurotoxicity (Acetylcholinesterase activity) biomarkers were evaluated in clams after a 28 days exposure period. The results obtained showed that the accumulation of As was not affected by the presence of the NPs. Our results demonstrated that higher injuries were noticed in clams exposed to NPs, with higher metabolic depression and oxidative stress, regardless of the presence of As. Furthermore, higher neurotoxicity was observed in clams exposed to the combination of both contaminants in comparison to the effects of As and NPs individually., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Intertidal species are frequently exposed to environmental changes associated with multiple stressors, which they must either avoid or tolerate by developing physiological and biochemical strategies. Some of the natural environmental changes are related with the tidal cycle which forces organisms to tolerate the differences between an aquatic and an aerial environment. Furthermore, in these environments, organisms are also subjected to pollutants from anthropogenic sources. The present study evaluated the impacts in Mytilus galloprovincialis exposed to multi-walled carbon nanotubes (0.01 mg/L MWCNTs) when continuously submersed or exposed to tides (5 h of low tide, 7 h of high tide) for 14 days. Our results demonstrated that mussels were physiologically and biochemically affected by MWCNTs, especially when exposed to tides. In fact, when only exposed to the carbon nanoparticles or only exposed to tides, the stress induced was not enough to activate mussels' antioxidant defenses which resulted in oxidative damage. However, when mussels were exposed to the combination of tides and MWCNTs increased metabolism was observed, associated with a possible higher production of reactive oxygen species (ROS), leading to a significant increase in the activities of antioxidant enzymes (superoxide dismutase, SOD and glutathione peroxide, GPx) and oxidized glutathione content (GSSG), preventing the occurrence of cellular damage, expressed as no lipid peroxidation (LPO) or protein carbonylation (PC). Therefore, organisms seemed to be able to tolerate MWCNTs and air exposure during tidal regime; however, the combination of both stressors induced higher oxidative stress. These findings indicate that the increasing presence of carbon nanoparticles in marine ecosystems can induce higher toxic impacts in intertidal organisms compared to organisms continuously submerged. Also, our results may indicate that air exposure can act as a cofounding factor on the assessment of different stressors in organisms living in coastal systems., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Salinity shifts in estuarine and coastal areas are becoming a topic of concern and are one of the main factors influencing nanoparticles behaviour in the environment. For this reason, the impacts of multi-walled carbon nanotubes (MWCNTs) under different seawater salinity conditions were evaluated on the common ragworm Hediste diversicolor, a polychaete species widely used as bioindicator of estuarine environmental quality. An innovative method to assess the presence of MWCNT aggregates in the sediments was used for the first time. Biomarkers approach was used to evaluate the metabolic capacity, oxidative status and neurotoxicity of polychaetes after long-term exposure. The results revealed an alteration of energy-related responses in contaminated polychaetes under both salinity conditions, resulting in an increase of metabolism and expenditure of their energy reserves (lower glycogen and protein contents). Moreover, a concentration-dependent toxicity (higher lipid peroxidation, lower ratio between reduced and oxidized glutathione and activation of antioxidant defences and biotransformation mechanisms) was observed in H. diversicolor, especially when exposed to low salinity. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs at both salinities.

The toxicity of carbon nanotubes (CNTs) is closely related to their physico-chemical characteristics as well as the physico-chemical parameters of the media where CNTs are dispersed. In a climate change scenario, changes in seawater salinity are becoming a topic of concern particularly in estuarine and coastal areas. Nevertheless, to our knowledge no information is available on how salinity shifts may alter the sensitivity (in terms of biochemical responses) of bivalves when exposed to different CNTs. For this reason, a laboratory experiment was performed exposing the Manila clam Ruditapes philippinarum, one of the most dominant bivalves of the estuarine and coastal lagoon environments, for 28 days to unfunctionalized multi-walled carbon nanotube MWCNTs (Nf-MWCNTs) and carboxylated MWCNTs (f-MWCNTs), maintained at control salinity (28) and low salinity 21. Concentration-dependent toxicity was demonstrated in individuals exposed to both MWCNT materials and under both salinities, generating alterations of energy reserves and metabolism, oxidative status and neurotoxicity compared to non-contaminated clams. Moreover, our results showed greater toxic impacts induced in clams exposed to f-MWCNTs compared to Nf-MWCNTs. In the present study it was also demonstrated how salinity shifts altered the toxicity of both MWCNT materials as well as the sensitivity of R. philippinarum exposed to these contaminates in terms of clam metabolism, oxidative status and neurotoxicity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Despite of the large array of available carbon nanotube (CNT) configurations that allow different industrial and scientific applications of these nanoparticles, their impacts on aquatic organisms, especially on invertebrate species, are still limited. To our knowledge, no information is available on how surface chemistry alteration (functionalization) of CNTs may impact the toxicity of these NPs to bivalve species after a chronic exposure. For this reason, the impacts induced by chronic exposure (28days) to unfunctionalized MWCNTs (Nf-MWCNTs) in comparison with functionalized MWCNTs (f-MWCNTs), were evaluated in R. philippinarum, by measuring alterations induced in clams' oxidative status, neurotoxicity and metabolic capacity. The results obtained revealed that exposure to both MWCNT materials altered energy-related responses, with higher metabolic capacity and lower glycogen, protein and lipid concentrations in clams exposed to these CNTs. Moreover, R. philippinarum exposed to Nf-MWCNTs and f-MWCNTs showed oxidative stress expressed in higher lipid peroxidation and lower ratio between reduced and oxidized glutathione, despite the activation of defense mechanisms (superoxide-dismutase, glutathione peroxidase and glutathione S-transferases) in exposed clams. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to both MWCNTs., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Multi-walled carbon nanotubes (MWCNTs) are one of the most important carbon Nanoparticles (NPs). The production and use of these NPs are increasing rapidly and, therefore, the need to assess their presence in the environment and associated risks has become of prime importance. Recent studies demonstrated the impacts of different NPs on bivalves, a taxonomic group where species tolerance to anthropogenic stressors, such as pollutants, is widely variable. The Manila clam Ruditapes philippinarum is one of the most commonly used bivalve species in environmental monitoring studies and ecotoxicology tests, however, to our knowledge, no information is available on biochemical alterations on this species due to MWCNTs exposure. Thus, the present study aimed to assess the toxic effects of different MWCNT concentrations (0.01; 0.10 and 1.00mg/L) in R. philippinarum biochemical (energy reserves, metabolic capacity, oxidative status and neurotoxicity) performance, after 28days of exposure. The results obtained revealed that exposure to MWCNTs altered energy-related responses, with higher metabolic capacity and lower glycogen and protein concentrations in clams exposed to these carbon NPs. Moreover, R. philippinarum exposed to MWCNTs showed oxidative stress expressed in higher lipid peroxidation and lower ratio between reduced and oxidized glutathione, despite the activation of defence mechanisms in exposed clams. Additionally, neurotoxicity was observed by inhibition of cholinesterases activity in organisms exposed to MWCNTs. The present study provides valuable information regarding how these emerging pollutans could become a potential risk for the environment and living organisms., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Multi-walled carbon nanotubes (MWCNTs) are one of the most important carbon Nanomaterials (NMs). The production and use of these carbon NMs is increasing rapidly and, therefore, the need to assess their presence in the environment and associated risks has become increasingly important. However, limited literature is available regarding the impacts induced in aquatic organisms by this pollutant, namely in invertebrate species. Diopatra neapolitana and Hediste diversicolor are keystone polychaete species inhabiting estuaries and shallow water bodies intertidal mudflats, frequently used to evaluate the impact of environmental disturbances in these systems. To our knowledge, no information is available on physiological and biochemical alterations on these two species due to MWCNTs exposure. Thus, the present study aimed to assess the toxic effects of different MWCNTs concentrations (0.01; 0.10 and 1.00mg/L) in both species physiological (regenerative capacity and respiration rate) and biochemical (energy reserves, metabolic activities, oxidative stress related biomarkers and neurotoxicity markers) performance, after 28 days of exposure. The results obtained revealed that exposure to MWCNTs induced negative effects on the regenerative capacity of D. neapolitana. Additionally, higher MWCNTs concentrations induced increased respiration rates in D. neapolitana. MWCNTs altered energy-related responses, with higher values of electron transport system activity, glycogen and protein concentrations in both polychaetes exposed to this contaminant. Furthermore, when exposed to MWCNTs both species showed oxidative stress with higher lipid peroxidation, lower ratio between reduced and oxidized glutathione, and higher activity of antioxidant (catalase and superoxide dismutase) and biotransformation (glutathione-S-transferases) enzymes in exposed organisms., (Copyright © 2016 Elsevier Inc. All rights reserved.)