Does salinity variation increase synergistic effects of triclosan and carbon nanotubes on Mytilus galloprovincialis? Responses on adult tissues and sperms

The use of carbon nanotubes (CNTs) is rapidly increasing and several scientific studies have addressed their toxicological properties. However, only a very small number of publications have deal with the interaction between CNTs and other molecules. Triclosan (TCS) is an antibacterial agent used in personal care and household products. Commonly detected in aquatic ecosystems, there is a strong evidence that aquatic biota is sensitive to this compound. Aside from emergent pollutants, aquatic organisms are continuously subjected to abiotic variations including salinities. Therefore, the main goal of the present study was to better understand how physio-chemical interactions of CNTs with TCS under different salinity levels (37, 28 and 19) affect the mussel species Mytilus galloprovincialis through the evaluation of biochemical alterations on gametes (sperms) and adult tissues, providing more ecologically relevant information on organisms' responses. The results showed toxicological effects in terms of sperm metabolic activity and intracellular reactive oxygen species production as well as cellular damage and alteration of metabolic capacity at the adult's stage when exposed to both contaminants acting alone and in combination, under tested salinities. Moreover, when the mussels were exposed to the combination of both contaminants, they showed major toxic impacts on both assessed biological levels (adult tissues and sperms) especially under control salinity. This suggests that toxicity upon mixture exposure compared to single-substance exposure may impair mussels' populations, affecting reproduction success and growth.

Biochemical performance of mussels, cockles and razor shells contaminated by paralytic shellfish toxins

Marine toxins in bivalves pose an important risk to human health, and regulatory authorities throughout the world impose maximum toxicity values. In general, bivalve toxicities due to paralytic shellfish toxins (PSTs) above the regulatory limit occur during short periods, but in some cases, it may be extended from weeks to months. The present study examines whether cockles (Cerastoderme edule), mussels (Mytilus galloprovincialis) and razor shells (Solen marginatus) naturally exposed to a bloom of Gymnodinium catenatum activated or suppressed biochemical responses as result of the presence of PSTs in their soft tissues. Toxins (C1+2, C3+4, GTX5, GTX6, dcSTX, dcGTX2+3 and dcNEO) and a set of biomarkers (ETS, electron transport system activity; GLY, glycogen; PROT, protein; SOD, superoxide dismutase; CAT, catalase; GPx, glutathione peroxidase; GST, glutathione S-transferases; LPO, lipid peroxidation; reduced (GSH) and oxidized (GSSG) glutathione contents and AChE, acetylcholinesterase activity) were determined in the three bivalve species. Specimens were harvested weekly in Aveiro lagoon, Portugal, along thirteen weeks. This period included three weeks in which bivalve toxicity exceeded largely the regulatory limit and the subsequence recovery period of ten weeks. Biochemical performance of the surveyed species clearly indicated that PSTs induce oxidative stress and neurotoxicity, with higher impact on mussels and razor shells than in cockles. The antioxidant enzymes CAT and GPx seemed to be the biomarkers better associated with toxin effects.

The effects of co-exposure of graphene oxide and copper under different pH conditions in Manila clam Ruditapes philippinarum

Carbon nanomaterials (CNM), such as graphene oxide (GO), have been the focus of study in several areas of science mostly due to their physical-chemical properties. However, data concerning the potential toxic effects of these CNM in bivalves are still scarce. When present in the aquatic systems, the combination with other contaminants, as well as pH environmental variations, can influence the behavior of these nanomaterials and, consequently, their toxicity. Thus, the main goal of this study was to evaluate the effect of exposure of clam Ruditapes philippinarum to GO when acting alone and in the combination with copper (Cu), under two pH levels (control 7.8 and 7.3). A 28-day exposure was performed and metabolism and oxidative stress-related parameters were evaluated. The effects caused by GO and Cu exposures, either isolated or co-exposed, showed a direct and dependent relationship with the pH in which the organisms were exposed. In clams maintained at control pH (7.8), Cu and GO + Cu treatments showed lower lipid peroxidation (LPO) and lower electron transport system (ETS) activity, respectively. In clams maintained at low pH, glutathione-S-transferases (GSTs) activities were increased in Cu and Cu + GO treatments, whereas reduced glutathione (GSH) levels were increased in Cu treatment and ETS activity was higher in GO + Cu. Thus, it can be observed that clams responses to Cu and GO were strongly modulated by pH in terms of their defense system and energy production, although this does not result into higher LPO levels.

Will temperature rise change the biochemical alterations induced in Mytilus galloprovincialis by cerium oxide nanoparticles and mercury?

It is known that, for marine coastal ecosystems, pollution and global warming are among the most threatening factors. Among emerging pollutants, nanoparticles (NPs) deserve particular attention as their possible adverse effects are significantly influenced by environmental factors such as salinity, pH and temperature, as well as by their ability to interact with other contaminants. In this framework, the present study aimed to evaluate the potential interactions between CeO₂ NPs and the toxic classic metal mercury (Hg), under current and warming conditions. The marine bivalve Mytilus galloprovincialis was used as biological model and exposed to CeO₂ NPs and Hg, either alone or in combination, for 28 day at 17 °C and 22 °C. A suite of biomarkers related to energetic metabolism, oxidative stress/damage, redox balance, and neurotoxicity was applied in exposed and non-exposed (control) mussels. The Hg and Ce accumulation was also assessed. Results showed that the exposure to CeO₂ NPs alone did not induce toxic effects in M. galloprovincialis. On the contrary, Hg exposure determined a significant loss of energetic metabolism and a general impairment in biochemical performances. Hg accumulation in mussels was not modified by the presence of CeO₂ NPs, while the biochemical alterations induced by Hg alone were partially canceled upon co-exposure with CeO₂ NPs. The temperature increase induced loss of metabolic and biochemical functions and the effects of temperature prevailed on mussels exposed to pollutants acting alone or combined.

Biomarker considerations in monitoring petrogenic pollution using the mussel Mytilus galloprovincialis

Mussels are worldwide bioindicators in pollution monitoring since they fulfil the requirements for being good sentinels. However, some methodological concerns arise in the use of particular biomarkers, particularly those displaying low enzymatic rates and/or limited responsiveness to chemicals and biological-related variability. In the present study, the suitability of oxidative stress and detoxification parameters when using mussels as sentinels of polycyclic aromatic hydrocarbon (PAH) pollution is addressed. Present results show that the S9 subcellular fraction of the digestive gland in mussels is an adequate and convenient matrix where to measure most pollution-related biomarkers. Furthermore, this work constitutes the first evidence of the potential suitability of using particular carboxylesterase (CE) activities in determining PAHs exposure in mussels. This fact could imply the replacement of more controversial cytochrome P450 components (phase I oxidation), which are only measurable in microsomal fractions, by CEs (measured in S9 fractions) as good alternatives for phase I reactions in PAH-exposed mussels. Some methodological considerations, such as the need of including commercial purified proteins in biomarker determinations for quality assurance, are evaluated.

Toxic impacts of rutile titanium dioxide in Mytilus galloprovincialis exposed to warming conditions

Climate change is leading to a gradual increase in the ocean temperature, which can cause physiological and biochemical impairments in aquatic organisms. Along with the environmental changes, the presence of emerging pollutants such as titanium dioxide (TiO₂) in marine coastal systems has also been a topic of concern, especially considering the interactive effects that both factors may present to inhabiting organisms. In the present study, it has been assessed the effects of the presence in water of particles of rutile, the most common polymorph of TiO₂, in Mytilus galloprovincialis, under actual and predicted warming conditions. Organisms were exposed to different concentrations of rutile (0, 5, 50, 100 μg/L) at control (18 ± 1.0 °C) and increased (22 ± 1.0 °C) temperatures. Histopathological and biochemical changes were evaluated in mussels after 28 days of exposure. Histopathological examination revealed similar alterations on mussels' gills and digestive glands with increasing rutile concentrations at both temperatures. Biochemical markers showed that contaminated mussels have an unchanged metabolic capacity at 18 °C, which increased at 22 °C. Although antioxidant defences were activated in contaminated organisms at 22 °C, cellular damage was still observed. Overall, our findings showed that histopathological impacts occurred after rutile exposure regardless of the temperature, while biochemical alterations were only significantly noticeable when temperature was enhanced to 22 °C. Thus, this study demonstrated that temperature rise may significantly enhance the sensitivity of bivalves towards emerging pollutants.

Anti-inflammatory drugs in the marine environment: Bioconcentration, metabolism and sub-lethal effects in marine bivalves

Pharmaceuticals such as non-steroidal anti-inflammatory drugs (NSAIDs) have been found in the marine environment. Although there is a large body of evidence that pharmaceutical drugs exert negative impacts on aquatic organisms, especially in the freshwater compartment, only limited studies are available on bioconcentration and the effects of NSAIDs on marine organisms. Bivalves have a high ecological and socio-economic value and are considered good bioindicator species in ecotoxicology and risk assessment programs. Therefore, this review summarizes current knowledge on the bioconcentration and the effects of three widely used NSAIDs, diclofenac, ibuprofen and paracetamol, in marine bivalves exposed under laboratory conditions. These pharmaceutical drugs were chosen based on their environmental occurrence both in frequency and concentration that may warrant their inclusion in the European Union Watch List. It has been highlighted that ambient concentrations may result in negative effects on wild bivalves after long-term exposures. Also, higher trophic level organisms may be more impacted due to food-chain transfer (e.g., humans are shellfish consumers). Overall, the three selected NSAIDs were reported to bioconcentrate in marine bivalves, with recognized effects at different life-stages. Immune responses were the main target of a long-term exposure to the drugs. The studies selected support the inclusion of diclofenac on the European Union Watch List and highlight the importance of extending research for ibuprofen and paracetamol due to their demonstrated negative effects on marine bivalves exposed to environmental realistic concentrations, under laboratory conditions.

Atlantic and Mediterranean populations of the widespread serpulid Ficopomatus enigmaticus: Developmental responses to carbon nanotubes

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.

Antioxidative and neurotoxicity effects of acute and chronic exposure of the estuarine polychaete Hediste diversicolor to paracetamol

The presence of anthropogenic drugs in the aquatic ecosystems is a reality nowadays, and a large number of studies have been reporting their putative toxic effects on wildlife. However, the majority of the studies published so far uses standard organisms, whose probability of becoming in contact with drugs in real scenarios of contamination is at least, low. The use of autochthonous organisms in ecotoxicity testing is thus mandatory, and the present study aimed to assess the feasibility of assessing oxidative based stress responses (enzymatic defenses, such as catalase, glutathione-s-transferases, and lipid peroxidation; neurotoxicity as an indirect outcome of oxidizing conditions) on a polychaete species, Hediste diversicolor, after being acutely and chronically exposed to the widely employed drug paracetamol. H. diversicolor showed to be responsive to paracetamol exposure. Data obtained after acute exposure to paracetamol showed that no antioxidant adaptive response was established, but cholinesterasic activity was enhanced. On the contrary, long term exposure of H. diversicolor individuals to paracetamol resulted in clear pro-oxidative effects, with catalase and cholinesterase inhibition, and a significant reduction in the levels of lipoperoxidation. Considering that some of the tested levels (especially those of the chronic test) were already reported in the wild, the here-obtained results are of high environmental significance. In addition, chronic exposure regime yielded more significant results, with important modification of more parameters, suggesting that realistic conditions of exposure are more suited for an integrated assessment of toxicity of drugs in aquatic organisms.

Biochemical and physiological responses of two clam species to Triclosan combined with climate change scenario

Ocean acidification and warming are among the man-induced factors that most likely impact aquatic wildlife worldwide. Besides effects caused by temperature rise and lowered pH conditions, chemicals of current use can also adversely affect aquatic organisms. Both climate change and emerging pollutants, including toxic impacts in marine invertebrates, have been investigated in recent years. However, less information is available on the combined effects of these physical and chemical stressors that, in nature, occur simultaneously. Thus, this study contrasts the effects caused by the antimicrobial agent and plastic additive, Triclosan (TCS) in the related clams Ruditapes philippinarum (invasive) and Ruditapes decussatus (native) and evaluates if the impacts are influenced by combined temperature and pH modifications. Organisms were acclimated for 30 days at two conditions (control: 17 °C; pH 8.1 and climate change scenario: 21 °C, pH 7.7) in the absence of the drug (experimental period I) followed by a 7 days exposure under the same water physical parameters but either in absence (unexposed) or presence of TCS at 1 μg/L (experimental period II). Biochemical responses covering metabolic, oxidative defences and damage-related biomarkers were contrasted in clams at the end of experimental period II. The overall picture showed a well-marked antioxidant activation and higher TCS bioaccumulation of the drug under the forecasted climate scenario despite a reduction on respiration rate and unaltered metabolism in the exposed clams. Since clams are highly consumed shellfish, the consequences for higher tissue bioaccumulation of anthropogenic chemicals to final consumers should be alerted not only at present conditions but more significantly under predicted climatic conditions for humans but also for other components of the marine trophic chain.

Can water remediated by manganese spinel ferrite nanoparticles be safe for marine bivalves?

In the last few years the use of nanoparticles (NPs) such as the manganese spinel ferrite (MnFe₂O₄) has been increasing, with a vast variety of applications including water remediation from pollutants as metal(oid)s. Although an increasing number of studies already demonstrated the potential toxicity of NPs towards aquatic systems and inhabiting organisms, there is still scarce information on the potential hazard of the remediated water using NPs. The present study aimed to evaluate the ecotoxicological safety of Pb contaminated seawater remediated with MnFe₂O₄, NPs, assessing the toxicity induced in mussels Mytilus galloprovincialis exposed to contaminated seawater and to water that was remediated using MnFe₂O₄, NPs. The results obtained demonstrated that seawater contaminated with Pb, NPs or the mixture of both (Pb + NPs) induced higher toxicity in mussels compared to organisms exposed to Pb, NPs and Pb + NPs after the remediation process. In particular, higher metabolic depression, oxidative stress and neurotoxicity were observed in mussels exposed to contaminated seawater in comparison to mussels exposed to remediated seawater.

FRI0462 PREDICTIVE FACTORS OF RELAPSE AFTER METHOTREXATE DISCONTINUATION IN JIA PATIENTS WITH INACTIVE DISEASE

Background:

Methotrexate (MTX) is the most widely used conventional synthetic disease-modifying antirheumatic drug (csDMARD) in the treatment of juvenile idiopathic arthritis (JIA).1,2When remission is achieved, questions remain about discontinuing MTX. There is some evidence that a longer period of inactive disease before MTX withdrawal is associated with lower likelihood of relapse, while both rheumatoid factor (RF) positive polyarthritis and extended oligoarthritis categories are associated with higher probability of disease relapse.2,3

Objectives:

To identify predictive factors of relapse after discontinuation of MTX in JIA patients with inactive disease.

Methods:

Prospective multicentre cohort study in patients diagnosed with JIA, according to the ILAR classification, using real world data from the Portuguese national register database, Reuma.pt (Fig 1).4We evaluated patients who have reached JADAS27 inactive disease (≤1 and no active extra-articular manifestations) and discontinued MTX before the age of 18 years-old.5Relapse was defined as recurrence (>1 or extra-articular manifestations) or restarting a DMARD.5To identify differences of relapse risk, univariate analyses were performed. Persistence in remission was estimated using the Kaplan-Meier method. Subsequently, Cox regression analyses were performed to identify predictors of relapse.

Results:

119 JIA patients discontinued MTX due to inactive disease (Fig 1). 69.7% were females and 60.6% had oligoarticular JIA. Sociodemographic and clinical characteristics are shown in Table 1. Relapse has occurred in 32.8%. Table 2 shows the disease characteristics at MTX initiation and discontinuation and at relapse or last visit.

In univariate analysis, relapse was associated with the use of NSAIDs at the time of MTX discontinuation (p=.027) and with a period of less than two years in inactive disease before MTX suspension (p=.040). We found no association with gender, race, immunology (RF, antinuclear and cyclic citrullinated peptide antibodies), MTX dose, discontinuation modality (tapering and spacing the doses or just tapering the dose), extra-articular manifestations, previous corticotherapy, family history, body mass index, JADAS, CHAQ index, inflammatory parameters, tender and swollen joint counts at MTX initiation or discontinuation nor with age at remission or at MTX suspension. Median persistence in inactive disease was significantly higher in patients with more than two years in remission before MTX discontinuation (p=.034) and in those who did not use NSAIDs at time of MTX discontinuation (p=.026) (Fig 2).

After adjustment for age at diagnosis, MTX tapering and JIA category, use of NSAIDs at the time of discontinuation (HR, 1.98 95%CI 1.03-3.82) and less than two years in remission (HR, 3.12 95%CI 1.35-7.13) remained associated with relapse.

Conclusion:

In this large cohort we found that the use of NSAIDs at the time of MTX discontinuation was associated with two times the likelihood of relapse. Like in other studies we also showed that the time in remission before MTX discontinuation is the main predictor of relapse. We found no association between the JIA category and the risk of relapse.

References:

[1]Hügle B 2016

[2]Klotsche J 2018

[3]Guzman J 2014

[4]Canhão H 2011

[6]Consolaro A 2014

Disclosure of Interests:

Soraia Azevedo: None declared, José Tavares-Costa: None declared, Ana Teresa Melo: None declared, Raquel Freitas: None declared, Marta Cabral: None declared, Marta Conde: None declared, Francisca Aguiar: None declared, Agna Neto: None declared, Ana Filipa Mourão: None declared, Filipa Oliveira-Ramos: None declared, Maria Jose Santos Speakers bureau: Novartis and Pfizer, Daniela Peixoto: None declared

Concentrations levels and effects of 17alpha-Ethinylestradiol in freshwater and marine waters and bivalves: A review

Pharmaceutical drugs are contaminants of emerging concern and are amongst the most frequent in the aquatic environment. Even though a vast literature indicate that pharmaceuticals exert negative impacts towards aquatic organisms, mainly in vertebrates, there is still limited information regarding the effects of these drugs in freshwater and marine bivalves. Marine bivalves have a high ecological and socio-economic value and are considered good bioindicator species in ecotoxicology and risk assessment programs. Furthermore, another lacking point on these studies is the absence of bioconcentration data, with no clear relationship between the concentration of drugs on tissue and the biological effects. 17alpha-ethinylestradiol (EE2) is a synthetic hormone with high estrogenic potency that was added to the Watch List adopted by the European Commission stating the priority substances to be monitored. Thus, this review summarizes the current knowledge on the concentration levels and effects of EE2 on freshwater and marine bivalves. The inclusion in the Watch List, the presence in freshwater and marine systems, and the impact exerted on aquatic biota, even at trace concentrations, justify the review devoted to this pharmaceutical drug. Globally the available studies found that EE2 induces individual and sub-individual (e.g. tissue, cellular, biochemical and molecular levels of biological organization) impacts in bivalves. Essentially, this estrogenic compound, even in trace concentrations, was found to have accumulated in wild and laboratory exposed bivalves. The most common effects reported were changes on the reproductive function and energy metabolism. The studies used in this review support keeping the EE2 on the Watch List and highlight the need to increase the number of monitorization studies since clear negative effects were exerted on bivalves by this drug.

FRI0165 RISK OF CKD IN MEMBRANOUS AND PROLIFERATIVE LUPUS NEPHRITIS - ANALYSIS OF A NATIONWIDE MULTICENTRE COHORT

Background:

Lupus nephritis (LN) is one of the most severe manifestations of Systemic Lupus Erythematosus.

Objectives:

1) To compare proliferative (PLN), membranous (MLN) and mixed LN regarding clinical and laboratory presentation. 2) To investigate predictors of progression to chronic kidney disease (CKD).

Methods:

Multicentre observational study, with retrospective analysis of a prospective cohort, using data from the Portuguese registry of rheumatic diseases – Reuma.pt. Patients with biopsy-proven PLN, MLN and mixed LN were included. Groups were compared using Pearson’s Chi-Square for categorical variables and One-Way ANOVA or Kruskal-Wallis for numerical variables. COX regression analysis was used to investigate predictors of CKD (defined as estimated glomerular filtration rate [eGFR] lower than 60 mL/min/1.73m2for at least 3 months) and Kaplan-Meier curves were drawn.

Results:

236 patients were included. Median follow-up was 8 years (IQR 11; maximum 35 years). As seen in table 1, the level of proteinuria did not differ between groups; however, MLN patients presented with significantly lower serum creatinine. Levels of complement C3 and C4 were reduced in PLN but normal in MLN patients, and there were fewer patients with positive anti-dsDNA antibodies in the MLN group (p<0.001). On univariable COX regression, mixed histology was associated with progression to CKD (HR 26 [95% CI 3 - 255], p 0.005) (figure 1), however, it lost significance after adjusting for eGFR. In fact, eGFR≤75 at one year after the renal biopsy (HR 21 [95% CI 7 - 65], p<0.001) was the strongest predictor of CKD, even after adjusting for hypertension or histology.

Table 1.

Comparative description of the Reuma.pt cohort of patients with proliferative, membranous and mixed LN

PLNMLNMixedPTotal, N186428Females, N (%)157 (85)39 (95)4 (50)0.004EthnicityWhite European, N (%)163 (90)31 (78)7 (88)0.115Other, N (%)19 (10)9 (23)1 (13)Age LN diagnosis(y), median (IQR)30 (20)34 (16)42 (25)0.409SLEDAI at LN diagnosis, median (IQR)16 (9)10 (10)21 (17)0.006*uPCR at LN diagnosis, median (IQR)1675 (2598)1698 (2153)2160 (3320)0.629Creatinine at LN diagnosis, median (IQR)0.80 (0.32)0.70 (0.20)1.00 (0.95)0.006*eGFR at LN diagnosis, mean ± SD98 ± 33112 ± 1782 ± 450.019*Albumin at LN diagnosis, mean ± SD34 ± 734 ± 730 ± 60.390C3 at LN diagnosis, mean ± SD0.65 ± 0.260.90 ± 0.350.53 ± 0.30<0.001*Positive anti-dsDNA LN diagnosis, N (%)115 (91)11 (48)6 (86)<0.001*Use of antimalarials, N (%)166 (94)36 (92)8 (100)0.688Use of immunosuppressants, N (%)163 (94)33 (87)8 (100)0.245Use of corticosteroids, N (%)145 (84)33 (85)7 (100)0.511CKD after LN diagnosis, N (%)27 (15)1 (3)3 (38)0.018*ESRD, N (%)7 (4)1 (3)2 (25)0.016Deaths, N (%)14 (8)2 (5)00.610

uPCR: urinary protein-creatinine ratio, mg/g; y: years; Creatinine presented in mg/dL, eGFR in mL/min/1.73m2,albumin in g/L and C3 in g/L

Note: Baseline data (LN diagnosis) in grey; other data refer to the course of disease

*Significant difference between the proliferative and membranous groups

Figure 1.

Kaplan-Meir curves showing cumulative survival free of CKD in patients with PLN, MLN and mixed LN

Conclusion:

Our results support previous findings from single-centre studies suggesting that MLN has a different serological profile than PLN, possibly reflecting different pathogenesis. Renal function at one year predicts long-term outcome in LN.

Disclosure of Interests:

Filipa Farinha: None declared, Sofia C Barreira: None declared, Maura Couto: None declared, Margarida Cunha: None declared, Diogo Fonseca: None declared, Raquel Freitas: None declared, Luís Inês: None declared, Mariana Luis: None declared, Carla Macieira: None declared, Ana Rita Prata: None declared, Joana Rodrigues: None declared, Bernardo Santos: None declared, Rita Pinheiro Torres: None declared, Ruth J. Pepper: None declared, Anisur Rahman: None declared, Maria Jose Santos Speakers bureau: Novartis and Pfizer

Biochemical and histopathological impacts of rutile and anatase (TiO2 forms) in Mytilus galloprovincialis

Titanium dioxide (TiO₂) particles have been widely used in various industrial applications and consumer products. Due to their large production and use, they will eventually enter into aquatic environments. Once in the aquatic environment TiO₂ particles may interact with the organisms and induce toxic effects. Since the most common crystallographic forms of TiO₂ are rutile and anatase, the present study evaluated the effect of these two forms of TiO₂ particles in Mytilus galloprovincialis. For this, mussels were exposed to different concentrations of rutile and anatase particles (0, 5, 50, 100 µg/L) for twenty-eight days. Ti concentrations, histopathological alterations and biochemical effects were evaluated. Similar Ti concentrations were found in mussels exposed to rutile and anatase, with the highest values in mussels exposed to the highest exposure concentration. Histopathological results demonstrated that both forms of TiO₂ induced alterations on gills and digestive glands along the increasing exposure gradient. Biochemical markers showed that mussels exposed to rutile maintained their metabolic capacity (assessed by the activity of the Electron Transport System, ETS), while anatase increased the metabolism of mussels. Mussels exposed to rutile increased their detoxifying defences which, due to the low tested concentrations, were sufficient to avoid cellular damage. On the other hand, mussels exposed to anatase suffered cellular damages despite the increase of the antioxidant defences which may be related to the high ETS activity. Both rutile and anatase particles were toxic to M. galloprovincialis, being the highest oxidative stress exerted by the crystalline form anatase.

Combined effects of salinity changes and salicylic acid exposure in Mytilus galloprovincialis

Pharmaceuticals and Personal care products (PPCPs) are frequently released into several marine matrices, representing significant environmental and ecotoxicological risks. Among the widest spread PPCPs in aquatic systems is Salicylic acid (SA), with known negative effects on marine and freshwater species. Nevertheless, the toxicity resulting from these emerging pollutants, including SA, together with climate change has still received little attention up to date. Among climate change related factors salinity is one that most affects aquatic organisms. To better understand the combined impacts of SA and salinity, the present study evaluated the biochemical alterations induced in Mytilus galloprovincialis mussels exposed to SA and different salinity levels, acting individually and in combination. The effects observed clearly highlighted that cellular damages were mainly observed at higher salinity (35), with no additive or synergistic effects derived from the combined presence of SA. Higher antioxidant capacity of mussels in the presence of SA may prevent increased LPO levels in comparison to uncontaminated mussels. Nevertheless, in the presence of SA mussels revealed loss of redox balance, regardless of the salinity level. Furthermore, mussels exposed to SA at control salinity showed increased metabolic capacity which decreased when exposed to salinities 25 and 35. These findings may indicate the protective capacity of mussels towards higher stressful conditions, with lower energy reserves expenditure when in the presence of SA and salinities out of their optimal range. Although limited cellular damages were observed, changes on mussel's redox balance, antioxidant mechanisms and metabolism derived from the combined exposure to SA and salinity changes may compromise mussel's growth and reproduction. Overall, the present study highlights the need to investigate the impacts induced by pollutants under present and future climate change scenarios, towards a more realistic environmental risk assessment.

New insights on the impacts of e-waste towards marine bivalves: The case of the rare earth element Dysprosium

With the technological advances and economic development, the multiplicity and wide variety of applications of electrical and electronic equipment have increased, as well as the amount of end-of-life products (waste of electrical and electronic equipment, WEEE). Accompanying their increasing application, there is an increasing risk to aquatic ecosystems and inhabiting organisms. Among the most common elements present in WEEE are rare earth elements (REE) such as Dysprosium (Dy). The present study evaluated the metabolic and oxidative stress responses of mussels Mytilus galloprovincialis exposed to an increasing range of Dy concentrations, after a 28 days experimental period. The results obtained highlighted that Dy was responsible for mussel's metabolic increase associated with glycogen expenditure, activation of antioxidant and biotransformation defences and cellular damage, with a clear loss of redox balance. Such effects may greatly impact mussel's physiological functions, including reproduction capacity and growth, with implications for population conservation. Overall the present study pointed out the need for more research on the toxic impacts resulting from these emerging pollutants, especially towards marine and estuarine invertebrate species.

Toxicological effects of the rare earth element neodymium in Mytilus galloprovincialis

The wide range of applications of rare earth elements (REE) is leading to their occurrence in worldwide aquatic environments. Among the most popular REE is Neodymium (Nd), being widely used in permanent magnets, lasers, and glass additives. Neodymium-iron-boron (NdFeB) magnets is the main application of Nd since they are used in electric motors, hard disk drives, speakers and generators for wind turbines. Recent studies have already evaluated the toxic potential of different REE, but no information is available on the effects of Nd towards marine bivalves. Thus, the present study evaluated the biochemical alterations caused by Nd in the mussel Mytilus galloprovincialis exposed to this element for 28 days. The results obtained clearly demonstrated that Nd was accumulated by mussels, leading to mussel's metabolic capacity increase and GLY expenditure, in an attempt to fuel up defense mechanisms. Antioxidant and biotransformation defenses were insufficient in the elimination of ROS excess, resulting from the presence of Nd and increased electron transport system activity, which caused cellular damages (measured by lipid peroxidation) and loss of redox balance (assessed by the ratio between reduced and oxidized glutathione). The results obtained clearly highlight the potential toxicity of REEs and, in particular of Nd, with impacts at cellular level, which may have consequences in mussel's survival, growth and reproduction, affecting mussel's population.

Oxidative stress, metabolic and histopathological alterations in mussels exposed to remediated seawater by GO-PEI after contamination with mercury

The modern technology brought new engineering materials (e.g. nanostructured materials) with advantageous characteristics such as a high capacity to decontaminate water from pollutants (for example metal(loid)s). Among those innovative materials the synthesis of nanostructured materials (NSMs) based on graphene as graphene oxide (GO) functionalized with polyethyleneimine (GO-PEI) had a great success due to their metal removal capacity from water. However, research dedicated to environmental risks related to the application of these materials is still non-existent. To evaluate the impacts of such potential stressors, benthic species can be a good model as they are affected by several environmental constraints. Particularly, the mussel Mytilus galloprovincialis has been identified by several authors as a bioindicator that responds quickly to environmental disturbances, with a wide spatial distribution and economic relevance. Thus, the present study aimed to evaluate the impacts caused in M. galloprovincialis by seawater previously contaminated by Hg and decontaminated using GO-PEI. For this, histopathological and biochemical alterations were examined. This study demonstrated that mussels exposed to the contaminant (Hg), the decontaminant (GO-PEI) and the combination of both (Hg + GO-PEI) presented an increment of histopathological, oxidative stress and metabolic alterations if compared to organisms under remediated seawater and control conditions The present findings highlight the possibility to remediate seawater with nanoparticles for environmental safety purposes.

The influence of climate change related factors on the response of two clam species to diclofenac

Diclofenac (DIC) is one of the non-steroidal anti-inflammatory drugs (NSAID) with higher consumption rates, used in both human and veterinary medicine. Previous studies already demonstrated the presence of this drug in aquatic environments and adverse effects towards inhabiting organisms. However, with the predictions of ocean acidification and warming, the impacts induced by DIC may differ from what is presently known and can be species-dependent. Thus, the present study aimed to comparatively assess the effects caused by DIC in the clams Ruditapes philippinarum and Ruditapes decussatus and evaluate if these impacts were influenced by pH and temperature. For this, organisms were acclimated for 30 days at two different temperature and pH (control conditions: pH 8.1, 17 °C; climate change forecasted scenario: pH 7.7, 20 °C) in the absence of drugs (experimental period I) followed by 7 days exposure under the same water physical parameters but in absence or presence of the pharmaceutical drug (at 1 μg/L, experimental period II). Biochemical responses covering metabolic capacity, oxidative stress and damage-related biomarkers were contrasted in clams at the end of the second experimental period. The results showed that under actual conditions, R. philippinarum individuals exposed to DIC presented enhanced antioxidant activities and reduced their respiration rate compared with non-contaminated clams. When exposed to the predicted climate change conditions, a similar response was observed in contaminated clams, but in this case clams increased their metabolic activities probably to fight the stress caused by the combination of both stressors. When R. decussatus was exposed to DIC, even at actual pH and temperature conditions, their antioxidant defences were also elevated but their baseline enzymatic activities were also naturally higher in respect to R. philippinarum. Although clams may use different strategies to prevent DIC damage, both clam species showed under low pH and high temperature limited oxidative stress impacts in line with a lower DIC bioaccumulation. The present findings reveal that predicted climate change related factors may not enhance the impacts of DIC in Ruditapes clams in a species-dependent manner although both displayed particular mechanisms to face stress.

Paralytic shellfish toxin profiles in mussel, cockle and razor shell under post-bloom natural conditions: Evidence of higher biotransformation in razor shells and cockles

Concentrations of the paralytic shellfish toxins GTX6, C1+2, GTX5, C3+4, dcSTX, dcNEO and dcGTX2+3 were determined by LC-FLD in composite samples of whole soft tissues of mussels (Mytilus galloprovincialis), cockles (Cerastoderma edule) and razor shells (Solen marginatus) after exposure to a Gymnodinium catenatum bloom. Specimens were harvested weekly during three months under natural depuration conditions in the Mira branch of Aveiro lagoon, Portugal. Under the decline of G. catenatum cell densities, elimination or transformation of the uptake toxins associated with the ingestion of toxic cells differed among the surveyed species. Ratio between the toxins dcSTX plus dcGTX2+3 plus dcNEO and toxins GTX6 plus GTX5 plus C1+2 plus C3+4 was used to illustrate the biotransformation occurring in the bivalves. Enhancement of the ratios was observed for razor shells and cockles seven weeks after the peak of the algal bloom. Most likely it reflects more intense biotransformation in razor shells and cockles than in mussels. Conversion into toxins of higher toxicity may prolong the bivalve toxicity. These results show the complexity of toxin elimination in bivalves under post-bloom conditions and emphasize the pertinence of monitoring programs of bivalve toxicity in order to protect human health.

Toxic impacts induced by Sodium lauryl sulfate in Mytilus galloprovincialis

Pharmaceuticals and personal care products (PPCPs) are continuously dispersed into the environment, as a result of human and veterinary use, reaching aquatic coastal systems and inhabiting organisms. However, information regarding to toxic effects of these compounds towards marine invertebrates is still scarce, especially in what regards to metabolic capacity and oxidative status alterations induced in bivalves after chronic exposure. In the present study, the toxic impacts of Sodium lauryl sulfate (SLS), an anionic surfactant widely used as an emulsifying cleaning agent in household and cosmetics, were evaluated in the mussel Mytilus galloprovincialis, after exposure for 28 days to different concentrations (0.0; 0.5; 1.0; 2.0 and 4.0 mg/L). For this, effects on mussels respitation rate, metabolic capacity and oxidative status were evaluated. The obtained results indicate a significant decrease on mussel's respiration rate after exposure to different SLS concentrations, an alteration that was accompanied by a decrease of bioconcentration factor along the increasing exposure gradient, especially at the highest exposure concentration. Nonetheless, the amount of SLS accumulated in organisms originated alterations in mussel's metabolic performance, with higher metabolic capacity up to 2.0 mg/L followed by a decrease at the highest tested concentration (4.0 mg/L). Mussels exposed to SLS revealed limited antioxidant defense mecanhisms but cellular damage was only observed at the highest exposure concentration (4.0 mg/L). In fact, up to 2.0 mg/L of SLS limited toxic impacts were observed, namely in terms of oxidative stress and redox balance. However, since mussel's respiration rate was greatly affected by the presence of SLS, the present study may highlight the potential threat of SLS towards marine bivalves, limiting their filtration capacity and, thus, affecting their global physiological development (including growth and reproduction) and ultimely their biochemical performance (afecting their defense capacity towards stressful conditons).

The influence of temperature and salinity on the impacts of lead in Mytilus galloprovincialis

Mussels, such as the marine bivalve Mytilus galloprovincialis are sentinels for marine pollution but they are also excellent bioindicators under laboratory conditions. For that, in this study we tested the modulation of biochemical responses under realistic concentrations of the toxic metal Lead (Pb) in water for 28 days under different conditions of salinity and temperature, including control condition (temperature 17 ± 1.0 °C and salinity 30 ± 1.0) as well as those within the range expected to occur due to climate change predictions (± 5 in salinity and + 4 °C in temperature). A comprehensive set of biomarkers was applied to search on modulation of biochemical responses in terms of energy metabolism, energy reserves, oxidative stress and damage occurrence in lipids, proteins as well as neurotoxicity signs. The application of an integrative Principal Coordinates Ordination (PCO) tool was successful and demonstrated that Pb caused an increase in the detoxification activity mainly evidenced by glutathione S-transferases and that the salinities 25 and 35 were, even in un-exposed mussels, responsible for cell damage seen as increased levels of lipid peroxidation (at salinity 25) and oxidised proteins (at salinity 35).

Engineered nanomaterials: From their properties and applications, to their toxicity towards marine bivalves in a changing environment

As a consequence of their unique characteristics, the use of Engineered Nanomaterials (ENMs) is rapidly increasing in industrial, agricultural products, as well as in environmental technology. However, this fast expansion and use make likely their release into the environment with particular concerns for the aquatic ecosystems, which tend to be the ultimate sink for this type of contaminants. Considering the settling behaviour of particulates, benthic organisms are more likely to be exposed to these compounds. In this way, the present review aims to summarise the most recent data available from the literature on ENMs behaviour and fate in aquatic ecosystems, focusing on their ecotoxicological impacts towards marine and estuarine bivalves. The selection of ENMs presented here was based on the OECD's Working Party on Manufactured Nanomaterials (WPMN), which involves the safety testing and risk assessment of ENMs. Physical-chemical characteristics and properties, applications, environmental relevant concentrations and behaviour in aquatic environment, as well as their toxic impacts towards marine bivalves are discussed. Moreover, it is also identified the impacts derived from the simultaneous exposure of marine organisms to ENMs and climate changes as an ecologically relevant scenario.