Multi-annual survey of health status disturbance in the Bilbao estuary (Bay of Biscay) based on sediment chemistry and juvenile sole (Solea spp.) histopathology

The Bilbao estuary (SE Bay of Biscay) is a recovering ecosystem whose sediments are still contaminated. They represent a potential risk for the biota including benthic and demersal species living in direct contact with the sediment. In this context, the present study aims to survey trends of the health status of the Bilbao estuary based on sediment chemistry and sole (Solea spp.) histopathology. Monitoring campaigns were carried out every autumn from 2011 to 2017 along the estuary. Contaminant levels were measured in sediments; liver, gills and gonads of juvenile fish were collected for histopathology. Overall, contaminant levels fluctuated throughout the years, with highest values recorded in the earlier years of the study period. Sole histopathology showed alterations of mild severity. Results permitted to assess the environmental health status of the Bilbao estuary during 7 years, although no clear temporal trend was detected. Longer-term monitoring programmes are necessary to confirm the ecosystem recovery.

Amitriptyline at an Environmentally Relevant Concentration Alters the Profile of Metabolites Beyond Monoamines in Gilt-Head Bream

The antidepressant amitriptyline is a widely used selective serotonin reuptake inhibitor that is found in the aquatic environment. The present study investigates alterations in the brain and the liver metabolome of gilt-head bream (Sparus aurata) after exposure at an environmentally relevant concentration (0.2 µg/L) of amitriptyline for 7 d. Analysis of variance-simultaneous component analysis is used to identify metabolites that distinguish exposed from control animals. Overall, alterations in lipid metabolism suggest the occurrence of oxidative stress in both the brain and the liver-a common adverse effect of xenobiotics. However, alterations in the amino acid arginine are also observed. These are likely related to the nitric oxide system that is known to be associated with the mechanism of action of antidepressants. In addition, changes in asparagine and methionine levels in the brain and pantothenate, uric acid, and formylisoglutamine/N-formimino-L-glutamate levels in the liver could indicate variation of amino acid metabolism in both tissues; and the perturbation of glutamate in the liver implies that the energy metabolism is also affected. These results reveal that environmentally relevant concentrations of amitriptyline perturb a fraction of the metabolome that is not typically associated with antidepressant exposure in fish. Environ Toxicol Chem 2019;00:1-13. © 2019 SETAC.

Prospective biomonitor and sentinel bivalve species for pollution monitoring and ecosystem health disturbance assessment in mangrove-lined Nicaraguan coasts

This research aims at contributing to the use of Polymesoda arctata, Anadara tuberculosa, and Larkinia grandis as prospective biomonitors and sentinels, surrogate of Crassostrea rhizophorae for pollution biomonitoring in mangrove-lined coastal systems. Localities were selected along the Nicaraguan coastline in the rainy and dry seasons during 2012-2013: A. tuberculosa and L. grandis were collected in the Pacific, and P. arctata in the Caribbean. The tissue concentration of metals, polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants (POPs) were integrated into pollution indices (chemical pollution index -CPI- and pollution load index -PLI-) and biological endpoints (flesh-condition, reproduction, histopathology and stress-on-stress) were determined as biomarkers of ecosystem health disturbance. In the Caribbean, contaminant tissue concentration was low in P. arctata, with some exceptions. Ag, As, Cd, Hg, Ni and V were mainly recorded during dry season, and PAHs and POPs (HCHs, DDTs, AHTN, PCBs and BDE85) during rainy season. Metals and PAHs were not a major threat in the study area; in contrast, high levels of HCHs and DDTs and low-to-moderate levels of musk fragrances and PBDEs were recorded. Minor differences were found in biological parameters albeit during the rainy season the LT50 values were low and seemingly associated to high PLI and CPI values. In the Pacific, the main pollutants recorded in A. tuberculosa and L. grandis were HCHs, DDTs, AHTN and PDBEs in rainy season and Cd in dry season. Although basic research is needed to understand the general biology, ecology and diseases in these Pacific species, biological endpoints comparable to those used in other sentinel bivalves are seemingly suitable biomarkers of health disturbance. Overall, Caribbean P. arctata and Pacific A. tuberculosa and L. grandis seem to be potential target species for pollution monitoring and ecosystem health disturbance assessment in mangrove-lined Nicaraguan coastal systems. Their use together with C. rhizophorae would provide opportunities for common approaches to be applied in inter-ocean countries of the Mesoamerican region.

Enhanced discrimination of basophilic cells on mussel digestive gland tissue sections by means of toluidine-eosin staining

Changes in the cell type composition of the digestive gland epithelium constitute a common and recognized biological response to stress in mussels. Usually, these changes are identified as alterations in the relative proportion of basophilic cells, determined in tissue sections stained with hematoxylin-eosin (H&E) and measured in terms of volume density of basophilic cells (Vv_BAS) after stereological quantification. However, the identification and discrimination of basophilic cells may be a difficult issue, even for a trained operator, especially when, in circumstances of environmental stress, basophilic cells lose their basophilia and the perinuclear area of digestive cells gains basophilia. Thus, the present study was aimed at exploring the best available practices (BAPs) to identify and discriminate basophilic cells on tissue sections of mussel digestive gland. In a first step, a thorough screening of potentially suitable staining methods was carried out; the final selection included several trichrome staining methods and some of their variants, as well as toluidine-based stains. Next, the sample processing (fixation/dehydration steps) was optimized. Toluidine-eosin (T&E) staining after fixation in 4% formaldehyde at 4 °C for 24 h was considered the BAP to identify and discriminate basophilic cells in the digestive gland of mussels. Using the mussel Mytilus galloprovincialis as a target organism, this approach was successfully applied to quantify Vv_BAS values after automated image analysis and compared with the conventional H&E staining in different field and laboratory tests. It is worth noting that Vv_BAS values were always higher after T&E staining than after H&E staining, apparently because discrimination of basophilic cells was enhanced. Thus, until more data are available, any comparison with Vv_BAS values obtained in previous studies using H&E staining must be done cautiously. Finally, the T&E staining was successfully used to discriminate basophilic cells in tissue sections of other marine molluscs of ecotoxicological interest, including Mytilus edulis, Mytilus trossulus, Crassostrea gigas and Littorina littorea.

The influence of short-term experimental fasting on biomarker responsiveness in oil WAF exposed mussels

Mussels are widely used in toxicological experimentation; however, experimental setups are not standardized yet. Although there is evidence of changes in biomarker values during food digestion and depending on the mussel nutritive status, the mode of feeding differs among toxicological experiments. Typically, mussels are fed with different diets in different long-term experiments, while fasting is the most common approach for short-term studies. Consequently, comparisons among experiments and reliable interpretations of biomarker results are often unfeasible. The present investigation aimed at determining the influence of fasting (against feeding with Isochrysis galbana) on biomarkers and their responsiveness in mussels exposed for 96 h to the water accommodated fraction (WAF) of a heavy fuel oil (0%, 6.25%, 12.5% and 25% WAF in sea water). PAH tissue levels in digestive gland and a battery of biomarkers were compared. WAF exposure led to decrease of cytochrome-C-oxidase activity, modulated glutathione-S-transferase activity, augmented lipid peroxidation, inhibited acetyl cholinesterase (AChE) activity, and led to lysosomal enlargement (Vv_LYS and S/V_LYS) and membrane destabilisation, lipofuscin accumulation, and histopathological alterations (Vv_BAS, MLR/MET and CTD ratio) in the digestive gland epithelium; and were integrated as IBR/n (biological response index). Overall, no significant changes were recorded in AChE activity, S/V_LYS and CTD ratio in any experimental treatment, while all the other biomarkers showed significant changes depending on the fasting/feeding condition, the exposure to WAF and/or their interaction. As a result, the integrated biomarker index IBR/n was higher at increasing WAF exposure levels both in fasted and fed mussels albeit the response was more marked in the latter. The response profiles were qualitatively similar between fasted and fed mussels but quantitatively more pronounced in fed mussels, especially upon exposure to the highest concentration (25% WAF). Therefore, it is highly recommended that mussels are also supplied with food during short-term, like during long-term toxicological experiments. This practice would avoid the interference of fasting with biological responses elicited by the tested chemicals and allow for reliable comparison with data obtained in long-term experiments and monitoring programmes.

Interactive effects of osmotic stress and burrowing activity on protein metabolism and muscle capacity in the soft shell clam Mya arenaria

Bioturbators such as sediment-dwelling marine bivalves are ecosystem engineers that enhance sediment-water exchange and benthic-pelagic coupling. In shallow coastal areas, bivalves are exposed to frequent disturbance and salinity stress that might negatively affect their activity and physiological performance; however, the mechanisms underlying these effects are not fully understood. We investigated the effects of osmotic stress (low and fluctuating salinity) and repeated burrowing on aerobic and contractile capacity of the foot muscle (assessed by the activity of succinate dehydrogenase and myosin ATPase) as well as the levels of organic osmolytes (free amino acids) and biochemical markers of protein synthesis and proteolysis in key osmoregulatory and energy storing tissues (gills and hepatopancreas, respectively) in a common bioturbator, the soft shell clam Mya arenaria. Osmotic stress and exhaustive exercise altered the foot muscle capacity of soft shell clams and had a strong impact on protein and amino acid homeostasis in tissues not directly involved in locomotion. Acclimation to constant low salinity (5 practical salinity units) depleted the whole-body free amino acid pool and affected protein synthesis but not protein breakdown in the gill. In contrast, fluctuating (5-15) salinity increased protein breakdown rate, suppressed protein synthesis, caused oxidative damage to proteins in the gill and selectively depleted whole-body glycine pool. Clams acclimated to normal salinity (15) increased the aerobic capacity of the foot muscle upon repeated burrowing, whereas acclimation to low and fluctuating salinity reduced this adaptive muscle plasticity. Under the normal and low salinity conditions, exhaustive exercise induced protein conservation pathways (indicated by suppression of protein synthesis and catabolism), but this effect was disrupted by fluctuating salinity. These findings indicate that exhaustive exercise and osmotic stress interactively affect whole-body protein homeostasis and functional capacity of the foot muscle in soft shell clams which might contribute to reduced burrowing activity of bivalve bioturbators in osmotically challenging environments such as estuaries and shallow coastal zones.

Study of bioconcentration of oxybenzone in gilt-head bream and characterization of its by-products

The widespread occurrence of UV filters such as oxybenzone (OXY) in the aquatic ecosystems has raised social and scientific concern due to their high bioaccumulation potential and possible adverse effects in organisms. Within this context, the aim of the present work was to study the uptake, distribution, metabolization and elimination of OXY in different tissues (liver, gill and muscle) and biofluids (bile and plasma) of gilt-head bream (Sparus aurata) in a controlled seawater ecosystem (50 ng/mL OXY) within a 14-day exposure. The highest OXY concentrations in all the tissue/biofluids were found at the end of the experiment. The highest OXY levels were found in bile (1.8-17 μg/mL). In the case of liver, the concentrations found (9-160 ng/g) were lower than those expected for a lipidic matrix, which could be explained by a high OXY metabolization. Up to 20 Phase I and Phase II by-products of OXY were annotated by means of liquid chromatography-high resolution mass spectrometry, of which 12 were reported for the first time. In addition to OXY, its by-products might also cause adverse effects and their biomonitoring is advisable in order to fully characterize OXY exposure.

Toxicology tailored low density oligonucleotide microarray for the thicklip grey mullets (Chelon labrosus): Biomarker gene transcription profile after caging in a polluted harbour

In aquatic organisms inhabiting polluted waters genes are activated to build an adaptive/compensatory defence against the possible effects of pollutants. Such responses can be used as biomarkers of exposure to chemical compounds, outlining the molecular mechanisms activated under specific pollution scenarios. With the aim of exploiting such approach in environmental health assessment, toxicologically relevant gene fragments were sequenced in the thicklip grey mullet (Chelon labrosus) and a toxicologically tailored low-density (160 genes) oligonucleotide microarray was customised. The tool was validated comparing organ/sex specific gene expression profiles and characterising responses under laboratory exposure to model chemicals. Finally, juvenile mullets were caged in a polluted harbour and hepatic gene expression profiles analysed after 5 and 21 days of deployment. Cages were deployed in the inner (IH) and outer (OH) Pasaia harbour, Bay of Biscay. Mussels (Mytilus galloprovincialis) were also caged as biological matrix for chemical bioaccumulation analysis and stress biomarkers measurements. Slightly higher concentrations of chemicals (metals, tributyltin, PAHs, phthalates) were quantified in IH than in OH, fish bile metabolites also revealing higher availability of PAHs in IH. Lysosome membrane stability in mussels was reduced, indicating stress condition in both sites. The developed microarray discriminated mullets showing distinctive expression profiles depending on site and deployment time. Genes related to immune and hypoxia responses were regulated comparing IH and OH at day 5. Phase I and II biotransformation genes, such as cyp2, cyp3 and ugt, were up-regulated in IH, together with the aryl hydrocarbon receptor 2 (ahr2) and the ahr repressor. Similarly, TBT-binding proteins and genes involved in lipid metabolism (pparγ, cyp7) were up-regulated with deployment time. Even if nowadays higher throughput approaches for gene expression analyses are available, the developed mullet tool constitutes a comprehensive tool to assess molecular responses of mullets exposed to pollutants, although it remains to be explored whether it can be applied to assess pollutant exposure in active pollution monitorings and in environmental health assessment.

Effects of dietary Pb and Cd and their combination on lysosomal and tissue-level biomarkers and histopathology in digestive gland of the land snail, Cantareus apertus (Born, 1778)

The present study was aimed at determining cell and tissue-level biomarkers and histopathological alterations in the green garden snail, Cantareus apertus (Born, 1778), exposed to different nominal dietary concentrations of Pb (25, 100 and 2500 mg Pb/kg), Cd (5, 10 and 100 mg Cd/kg) and their combination (25 mg Pb + 5 mg Cd/Kg, 100 mg Pb + 10 mg Cd/kg and 2500 mg Pb + 100 mg Cd/ kg) for 1 and 8 weeks. Lead and Cd exerted histopathological effects on the digestive gland in a dose-dependent manner and related to lysosomal and tissue-level biomarkers. The biological responses observed included digestive cell vacuolisation and numerical atrophy, calcium cell hydropic degeneration, excretory cell hypertrophy, inflammatory responses, blood vessel congestion, and disruption of the blood vessel wall and the interstitial connective tissue. Lysosomal enlargement and transient intracellular accumulation of neutral lipids and lipofuscins were also observed, together with alterations in the cell type composition and thinning of the digestive gland epithelium and with diverticular distortion. This response profile fits well with the biological effects reported after metal exposure in gastropods from other regions, as well as with data obtained in parallel studies dealing with metal bioaccumulation and intralysosomal accumulation, mortality, feeding, growth, oxidative stress and neurotoxicity exerted elicited by Pb, Cd and their mixture in green garden snails under the present experimental conditions. Consequently, C. apertus seems to be a suitable model species for the biomarker-based assessment of the biological effects of Pb and Cd, alone or in combinations, thus providing a challenging opportunity to advance in identifying suitable sentinel species for metal pollution biomonitoring and ecosystem health assessment in soil ecosystems in Northern Africa.

Assessment of ecosystem health disturbance in mangrove-lined Caribbean coastal systems using the oyster Crassostrea rhizophorae as sentinel species

This investigation was aimed at contributing to develop a suitable multi-biomarker approach for pollution monitoring in mangrove-lined Caribbean coastal systems using as sentinel species, the mangrove cupped oyster, Crassostrea rhizophorae. A pilot field study was carried out in 8 localities (3 in Nicaragua; 5 in Colombia), characterized by different environmental conditions and subjected to different levels and types of pollution. Samples were collected in the rainy and dry seasons of 2012-2013. The biological effects at different levels of biological complexity (Stress-on-Stress response, reproduction, condition index, tissue-level biomarkers and histopathology) were determined as indicators of health disturbance, integrated as IBR/n index, and compared with tissue burdens of contaminants in order to achieve an integrative biomonitoring approach. Though modulated by natural variables and confounding factors, different indicators of oyster health, alone and in combination, were related to the presence of different profiles and levels of contaminants present at low-to-moderate levels. Different mixtures of persistent (As, Cd, PAHs) and emerging chemical pollutants (musk fragrances), in combination with different levels of organic and particulate matter resulting from seasonal oceanographic variability and sewage discharges, and environmental factors (salinity, temperature) elicited a different degree of disturbance in ecosystem health condition, as reflected in sentinel C. rhizophorae. As a result, IBR/n was correlated with pollution indices, even though the levels of biological indicators of health disturbance and pollutants were low-to-moderate, and seasonality and the incidence of confounding factors were remarkable. Our study supports the use of simple methodological approaches to diagnose anomalies in the health status of oysters from different localities and to identify potential causing agents and reflect disturbances in ecosystem health. Consequently, the easy methodological approach used herein is useful for the assessment of health disturbance in a variety of mangrove-lined Caribbean coastal systems using mangrove cupped oysters as sentinel species.

Tracing platinum accumulation kinetics in oyster Crassostrea gigas, a sentinel species in coastal marine environments

Platinum Group Elements (PGEs) are extremely scarce in the Earth's Crust and of strong interest for high-end technologies due to their specific properties. They belong to the Technology Critical Elements (TCEs) for which use is forecast to increase, implying growing emissions into the environment in the following years. In particular, with the intensive use of platinum (Pt) in car catalytic converters, the anthropogenic geochemical cycle of this element has surpassed the natural cycle. Yet, environmental Pt levels are still in the sub picomolar range, making its analytical detection a challenge. Few studies cover the behavior of Pt in marine waters in terms of speciation, reactivity and possible transfer to the biota. In this study, oysters (Crassostrea gigas) from an unpolluted estuary were exposed to the stable isotope ¹⁹⁴Pt in seawater at a range of concentrations during 35days. Seawater was renewed daily and spiked to three nominal Pt concentrations (50, 100, and 10,000ng·L^-1) for two replicate series. In addition, control conditions were monitored. Five oysters from each tank were dissected after 3, 7, 14, 21, 28, 35days of Pt exposure, and analyzed by ICP-MS. Accuracy of this analytical method applied to biological matrix was checked by an inter-method comparison with a voltammetrical technique. A concentration-dependent accumulation of Pt in oysters increasing with exposure time occurred. After 28days, oyster Pt accumulation from low and intermediate exposure conditions reached a plateau. This was not the case of the highest exposure condition for which oyster tissues showed increasing concentrations until the last day of the experiment. A linear correlation exists between seawater concentrations and Pt content in oysters for low and intermediate exposure concentrations i.e. closer to environmental concentrations. By showing high Pt accumulation potential, oysters may serve as sentinels, ensuring biomonitoring of Pt concentrations in marine coastal waters.

Biotransformation of 8:2 polyfluoroalkyl phosphate diester in gilthead bream (Sparus aurata)

Polyfluoroalkyl phosphate esters (PAPs) are high production volume surfactants used in the food contact paper and packaging industry. PAPs may transform to persistent perfluoroalkyl carboxylic acids (PFCAs) under biotic conditions, but little is known about their fate and behavior in aquatic organisms. Here we report for the first time on the uptake, tissue distribution, and biotransformation of 8:2 polyfluoroalkyl phosphate diester (8:2 diPAP) in fish. Gilt-head bream (Sparus aurata) were dosed via the diet (8:2 diPAP at 29μg/g) for 7days, during which time 8:2 diPAP and its transformation products were monitored in plasma, liver, muscle, gills, bile and brain. 8:2 diPAP tended to accumulate in liver, plasma and gills, and to a lesser extent in muscle, bile and brain. Several transformation products (observed previously in other organisms) were also observed in most tissues and biofluids, including both saturated and unsaturated fluorotelomer acids (8:2 FTCA, 8:2 FTUCA, 7:3 FTCA), and perfluorooctanoic acid (PFOA). 8:2 FTCA was the major metabolite in all tissues/biofluids, except for bile, where PFOA occurred at the highest concentrations. Unexpectedly high PFOA levels (up to 3.7ng/g) were also detected in brain. Phase 2 metabolites, which have been reported in fish following exposure to fluorotelomer alcohols, were not observed in these experiments, probably due to their low abundance. Nevertheless, the detection of PFOA indicates that exposure to PAPs may be an indirect route of exposure to PFCAs in fish.

Integrative biomarker assessment of the effects of chemically and mechanically dispersed crude oil in Pacific oysters, Crassostrea gigas

The impact of dispersed crude oil and dispersant on adult Pacific oysters, Crassostrea gigas, was evaluated through an integrative biomarker approach including (1) biochemical (plasma catecholase- and laccase-type phenoloxidase and superoxide dismutase), (2) histological (digestive cell lysosomal responses, digestive gland histopathology) and (3) physiological (flesh condition index) endpoints in the haemolymph and digestive gland. Adult oysters were exposed to non-contaminated water (control), chemically-dispersed oil (Brut Arabian Light), mechanically-dispersed oil and dispersant (FINASOL®) alone for 2days, and further depurated in non-contaminated water for 4weeks. After exposure to chemically and mechanically dispersed oil oysters exhibited induction of plasma laccase-type phenoloxidase and superoxide dismutase activities, enlargement of digestive cell lysosomes, lipofuscin accumulation, reduced neutral lipid content and atrophy of digestive gland diverticula; more markedly on exposure to chemically dispersed oil. From the studied biomarkers, only lysosomal biomarkers were significantly affected after exposure to the dispersant alone. This included lysosomal enlargement, neutral lipid depletion and lipofuscin accumulation in the digestive gland epithelium. A recovery of plasma enzyme activities was observed after 4weeks of depuration. The integrative biological response index indicated that chemically dispersed oil caused significantly higher stress to C. gigas than the mechanically-dispersed one or the dispersant alone; nevertheless, the response seems to be reversible after depuration.

Successive Onset of Molecular, Cellular and Tissue-Specific Responses in Midgut Gland of Littorina littorea Exposed to Sub-Lethal Cadmium Concentrations

Cadmium (Cd) is one of the most harmful metals, being toxic to most animal species, including marine invertebrates. Among marine gastropods, the periwinkle (Littorina littorea) in particular can accumulate high amounts of Cd in its midgut gland. In this organ, the metal can elicit extensive cytological and tissue-specific alterations that may reach, depending on the intensity of Cd exposure, from reversible lesions to pathological cellular disruptions. At the same time, Littorina littorea expresses a Cd-specific metallothionein (MT) that, due to its molecular features, expectedly exerts a protective function against the adverse intracellular effects of this metal. The aim of the present study was, therefore, to assess the time course of MT induction in the periwinkle’s midgut gland on the one hand, and cellular and tissue-specific alterations in the digestive organ complex (midgut gland and digestive tract) on the other, upon exposure to sub-lethal Cd concentrations (0.25 and 1 mg Cd/L) over 21 days. Depending on the Cd concentrations applied, the beginning of alterations of the assessed parameters followed distinct concentration-dependent and time-dependent patterns, where the timeframe for the onset of the different response reactions became narrower at higher Cd concentrations compared to lower exposure concentrations.

Chronic environmental stress enhances tolerance to seasonal gradual warming in marine mussels

In global climate change scenarios, seawater warming acts in concert with multiple stress sources, which may enhance the susceptibility of marine biota to thermal stress. Here, the responsiveness to seasonal gradual warming was investigated in temperate mussels from a chronically stressed population in comparison with a healthy one. Stressed and healthy mussels were subjected to gradual temperature elevation for 8 days (1°C per day; fall: 16–24°C, winter: 12–20°C, summer: 20–28°C) and kept at elevated temperature for 3 weeks. Healthy mussels experienced thermal stress and entered the time-limited survival period in the fall, became acclimated in winter and exhibited sublethal damage in summer. In stressed mussels, thermal stress and subsequent health deterioration were elicited in the fall but no transition into the critical period of time-limited survival was observed. Stressed mussels did not become acclimated to 20°C in winter, when they experienced low-to-moderate thermal stress, and did not experience sublethal damage at 28°C in summer, showing instead signs of metabolic rate depression. Overall, although the thermal threshold was lowered in chronically stressed mussels, they exhibited enhanced tolerance to seasonal gradual warming, especially in summer. These results challenge current assumptions on the susceptibility of marine biota to the interactive effects of seawater warming and pollution.

Bioconcentration and Biotransformation of Amitriptyline in Gilt-Head Bream

Extensive global use of the serotonin-norepinephrine reuptake inhibitor Amitriptyline (AMI) for treatment of mental health problems has led to its common occurrence in the aquatic environment. To assess AMI bioconcentration factors, tissue distribution, and metabolite formation in fish, we exposed gilt-head bream (Sparus aurata) to AMI in seawater for 7 days at two concentrations (0.2 μg/L and 10 μg/L). Day 7 proportional bioconcentration factors (BCFs) ranged from 6 (10 μg/L dose, muscle) to 127 (0.2 μg/L dose, brain) and were consistently larger at the low dose level. The relative tissue distribution of AMI was consistent at both doses, with concentrations decreasing in the order brain ≈ gill > liver > plasma > bile ≫ muscle. Using a suspect screening workflow based on liquid chromatography-high resolution (Orbitrap) mass spectrometry we identified 33 AMI metabolites (both Phase I and Phase II), occurring mostly in bile, liver and plasma. Ten structures are reported for the first time. Remarkably, all 33 metabolites retained the tricyclic ring structure common to tricyclic antidepressants, which may be toxicologically relevant. Collectively these data indicate that, in addition to AMI, a broad suite of metabolites should be included in biomonitoring campaigns in order to fully characterize exposure in aquatic wildlife.

Lysosomal responses to heat-shock of seasonal temperature extremes in Cd-exposed mussels

The present study was aimed at determining the effect of temperature extremes on lysosomal biomarkers in mussels exposed to a model toxic pollutant (Cd) at different seasons. For this purpose, temperature was elevated 10°C (from 12°C to 22°C in winter and from 18°C to 28°C in summer) for a period of 6h (heat-shock) in control and Cd-exposed mussels, and then returned back to initial one. Lysosomal membrane stability and lysosomal structural changes in digestive gland were investigated. In winter, heat-shock reduced the labilisation period (LP) of the lysosomal membrane, especially in Cd-exposed mussels, and provoked transient lysosomal enlargement. LP values recovered after the heat-shock cessation but lysosomal enlargement prevailed in both experimental groups. In summer, heat-shock induced remarkable reduction in LP and lysosomal enlargement (more markedly in Cd-exposed mussels), which recovered within 3 days. Besides, whilst heat-shock effects on LP were practically identical for Cd-exposed mussels in winter and summer, the effects were longer-lasting in summer than in winter for control mussels. Thus, lysosomal responsiveness after heat-shock was higher in summer than in winter but recovery was faster as well, and therefore the consequences of the heat shock seem to be more decisive in winter. In contrast, inter-season differences were attenuated in the presence of Cd. Consequently, mussels seem to be better prepared in summer than in winter to stand short periods of abrupt temperature change; this is, however, compromised when mussels are exposed to pollutants such as Cd.

Differences in copper bioaccumulation and biological responses in three Mytilus species

Mytilus species are important organisms in marine systems being highly abundant and widely distributed along the coast of Europe and worldwide. They are typically used in biological effects studies and have a suite of biological effects endpoints that are frequently measured and evaluated for stress effects in laboratory experiments and field monitoring programmes. Differences in bioaccumulation and biological responses of the three Mytilus species following exposure to copper (Cu) were investigated. A laboratory controlled exposure study was performed with three genetically confirmed Mytilus species; M. galloprovincialis, M. edulis and M. trossulus. Chemical bioaccumulation and biomarkers were assessed in all three Mytilus species following a 4 day and a 21 day exposure to waterborne copper concentrations (0, 10, 100 and 500μg/L). Differences in copper bioaccumulation were measured after both 4 and 21 days, which suggests some physiological differences between the species. Furthermore, differences in response for some of the biological effects endpoints were also found to occur following exposure. These differences were discussed in relation to either real physiological differences between the species or merely confounding factors relating to the species natural habitat and seasonal cycles. Overall the study demonstrated that differences in chemical bioaccumulation and biomarker responses between the Mytilus spp. occur with potential consequences for mussel exposure studies and biological effects monitoring programmes. Consequently, the study highlights the importance of identifying the correct species when using Mytilus in biological effects studies.

Combining chemical and biological endpoints, a major challenge for twenty-first century's environmental specimen banks

Environmental specimen banks (ESBs) are not a new phenomenon, but in the last decades, the steep rate in the establishment of new ESBs is a sign to address new research approaches for scientists. In this way, environmental biobanking is becoming a well-organized and effective vehicle to collect samples of high quality making them available for future researchers. The endpoints promoted in the ESBs are mainly based on chemical approaches, but the necessity to add biological endpoint is fundamental (e.g., assessment of the environmental health status). Moreover, advances and development of high sensitive, high-throughput techniques along with ecotoxicological approaches based on biomarkers are stimulating a new demand for stored specimens and associated data. Like in chemically targeted environmental specimen banking, the banked samples for the assessment of biological effects also require guidance informed by knowledge of their practices and challenges, along with policies for the correct advancement of research goals and appropriate and effective biobank governance.

Season-dependent effects of elevated temperature on stress biomarkers, energy metabolism and gamete development in mussels

In coastal areas, sessile species can be severely affected by thermal stress associated to climate change. Presently, the effect of elevated temperature on metabolic, cellular and tissue-level responses of mussels was determined to assess whether the responses vary seasonally with seawater temperature and reproductive stage. Mussels were collected in fall, winter and summer, and (a) maintained at 16, 12, and 20 °C respectively or (b) subject to gradual temperature elevation for 8 days (+1 °C per day; from 16 to 24 °C in fall, from 12 to 20 °C in winter and from 20 to 28 °C in summer) and further maintained at 24 °C (fall), 20 °C (winter) and 28 °C (summer) for the following 6 days. Temperature elevation induced membrane destabilization, lysosomal enlargement, and reduced the aerobic scope in fall and summer whereas in winter no significant changes were found. Changes at tissue-level were only evident at 28 °C. Gamete development was impaired irrespective of season. Since the threshold of negative effects of warming was close to ambient temperatures in summer (24 °C or above) studied mussel populations would be vulnerable to the global climate change.

Health status assessment through an integrative biomarker approach in mussels of different ages with a different history of exposure to the Prestige oil spill

A battery of cell and tissue-level biomarkers was applied in mussels of 6 size-classes collected from Galicia and the Basque coast in summer 2007 in an attempt to examine the health status of individuals affected as adults (mature before 2003), affected during their developmental or juvenile stages (2003-2004 offspring), or not directly affected by the Prestige oil spill (POS) exposure (presumably 2005-2006 offspring). This battery of biomarkers was akin to those formerly applied on mussels of 3.5-4.5 cm shell length for which there exist biomarker reference values in the studied geographical areas. The cause-effect relationship between biological responses and the different history of exposure to POS fuel oil was intricate for different reasons: (a) growth rate was dissimilar in mussels of the two studied localities and much lower than expected, (b) a chronological basis could not be directly associated to POS events (all mussels except the smallest from Galicia had been subjected to the direct POS impact at one or another stage of their life-cycle); and (c) some biomarkers and histopathology seemingly depended on size/age irrespectively of the locality and the POS chronology. As a whole, the present study gives a very useful set of reference values of biomarkers obtained for Mytilus galloprovincialis of different size-classes. Finally, it is recommended that Mussel Watch programmes should be designed by standardising the age of the sentinel mussels rather than their size, especially if the programme covers large or diverse geographical areas, if long-term trends are relevant or if significant pollution effects on growth are expected.

Combined effects of thermal stress and Cd on lysosomal biomarkers and transcription of genes encoding lysosomal enzymes and HSP70 in mussels, Mytilus galloprovincialis

In estuaries and coastal areas, intertidal organisms may be subject to thermal stress resulting from global warming, together with pollution. In the present study, the combined effects of thermal stress and exposure to Cd were investigated in the endo-lysosomal system of digestive cells in mussels, Mytilus galloprovincialis. Mussels were maintained for 24h at 18°C and 26°C seawater temperature in absence and presence of 50 μg Cd/L seawater. Cadmium accumulation in digestive gland tissue, lysosomal structural changes and membrane stability were determined. Semi-quantitative PCR was applied to reveal the changes elicited by the different experimental conditions in hexosaminidase (hex), β-glucuronidase (gusb), cathepsin L (ctsl) and heat shock protein 70 (hsp70) gene transcription levels. Thermal stress provoked lysosomal enlargement whilst Cd-exposure led to fusion of lysosomes. Both thermal stress and Cd-exposure caused lysosomal membrane destabilisation. hex, gusb and ctsl genes but not hsp70 gene were transcriptionally up-regulated as a result of thermal stress. In contrast, all the studied genes were transcriptionally down-regulated in response to Cd-exposure. Cd bioaccumulation was comparable at 18°C and 26°C seawater temperatures but interactions between thermal stress and Cd-exposure were remarkable both in lysosomal biomarkers and in gene transcription. hex, gusb and ctsl genes, reacted to elevated temperature in absence of Cd but not in Cd-exposed mussels. Therefore, thermal stress resulting from global warming might influence the use and interpretation of lysosomal biomarkers in marine pollution monitoring programmes and, vice versa, the presence of pollutants may condition the capacity of mussels to respond against thermal stress in a climate change scenario.

Zonation in the digestive tract of Eisenia fetida: implications in biomarker measurements for toxicity assessment

Eisenia fetida is a model species for soil health assessment and different biomarkers that detect either the presence of bioavailable contaminants or their biological effect have been developed. These parameters are performed in a target tissue or whole earthworm, without considering the marked zonation in histological organisation, enzyme activities and gene expression pattern existing along the body. Thus, the present work was aimed at (a) characterising the morphofunctional heterogeneity along the digestive tract of E. fetida in tissue morphology and turnover, lysosomal enzyme markers (β-glucuronidase, β-GUS; hexosaminidase, HEX), lipofuscin contents (LPF) and metallothionein (MT) and catalase (CAT) gene expression; and (b) determining whether the responsiveness to Cd exposure varies among tissues and along the digestive tract. HEX and β-GUS exhibited a heterogeneous distribution pattern along and across the digestive tract and Cd exposure caused a marked decrease of HEX and an increase of β-GUS activity. Likewise, the significant decrease of cell turnover and the induction of MT transcription were was zone-dependent. Therefore, in was concluded that the consideration of the zonation when applying biomarker for toxicity assessment would reduce the intrinsic variability that results from overlooking the marked morphofunctional heterogeneity that exists in annelids along their body axis.