Maria Pavlaki | University of Aveiro (original) (raw)

Papers by Maria Pavlaki

Water

Bioaccumulation of cadmium was assessed in different tissues of the benthic fish Solea senegalens... more Bioaccumulation of cadmium was assessed in different tissues of the benthic fish Solea senegalensis. Juvenile Senegalese soles were simultaneously exposed to cadmium-contaminated diet (Hediste diversicolor) and water during 14 days and allowed to depurate for another 14 days. Cadmium content was measured in muscle, gills, liver and intestine, with recorded values increasing in these tissues in this same order. Muscle showed a considerably lower cadmium accumulation after 14 days of uptake. Cadmium kinetics in juvenile Senegalese soles revealed that the highest uptake flux of this metal occurred in the intestine. Cadmium depuration from the liver was not detected, which suggests the existence of a storage compartment for this metal in Solea senegalensis during uptake and depuration. Comparisons between maximum acceptable values for cadmium in the muscle, the Target Hazard Quotient and the Estimated Weekly Intake, indicated that acceptable limits were not exceeded, and the muscle of j...

Environmental Toxicology and Chemistry

The present study assessed cadmium uptake and depuration rates in the euryhaline estuarine shrimp... more The present study assessed cadmium uptake and depuration rates in the euryhaline estuarine shrimp Palaemon varians under different exposure routes. Postlarval shrimp were exposed for 4 d under different exposure routes: contaminated water, contaminated diet, and a 2-way exposure scenario where both contaminated water and diet were used. After exposure, postlarval shrimp were transferred to a clean medium and fed a noncontaminated diet for 96 h. Bioaccumulation via the different exposure routes was modeled with a standard first-order, one-compartment toxicokinetics model and one with an additional parameter reflecting an inert fraction or storage compartment. The simultaneous 2-way exposure (through water and diet) resulted in accumulation being almost twice as high as the sum of the individual exposure routes, thus indicating that accumulation from multiple routes may be more than additive. Cadmium uptake from water was faster than uptake from food maintained for 48 h at that same cadmium concentration. Shrimp were unable to eliminate cadmium from their body, showing no depuration during 96 h after exposure via different routes, thus suggesting that a longer depuration period is needed. Model comparisons did not provide a significantly better fit when the model included the presence of an inert fraction. The present study highlights the importance of assessing accumulation using multiple exposure routes compared with individual routes because the latter may underestimate bioaccumulation. Environ Toxicol Chem 2018;37:1614-1622. © 2018 SETAC.

Ecotoxicology and environmental safety, Jan 18, 2017

mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for s... more mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd(2+) ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd(2+) ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd(2+) speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of ...

Science of The Total Environment, 2016

Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, w... more Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, which potentiate their emission to the environment. The toxicity of Ag-NP has been associated with the release of Ag ions (Ag(+)), which are more toxic to aquatic organisms than Ag-NP. In this study, a toxicokinetics approach was applied to compare the potential of Daphnia magna to accumulate Ag from either Ag-NP or AgNO3 through different exposure routes: a) water, b) diet and c) water and diet. A one-compartment kinetics model was applied to describe the development of Ag body concentrations over time and derive uptake (k1w; k1d) and elimination (k2) rate constants. Under water-only exposure, AgNO3 induced higher Ag uptake rate constants and bioconcentration factors when compared to Ag-NP. For dietary exposure, no differences in Ag concentrations in D. magna, along with the kinetics parameters, were found for both Ag forms. Simultaneous water and dietary exposures to Ag-NP induced higher Ag concentrations in D. magna compared to AgNO3. In this combined exposure, uptake from water explains most for the increase in Ag body concentration in D. magna for Ag-NP exposure, whereas uptake from the diet was the major contributor for the increase in Ag concentration in D. magna under AgNO3 exposure. Biomagnification was not observed for any of the exposure routes applied in this study, neither for Ag-NP nor for AgNO3.

Environmental Toxicology and Chemistry, 2016

Silver nanoparticles (AgNP) are highly used worldwide, which will most likely lead to their relea... more Silver nanoparticles (AgNP) are highly used worldwide, which will most likely lead to their release to the environment and subsequently increase environmental concentrations. Therefore studying AgNPs' deleterious effects to organisms is crucial to understand their environmental impacts. The freshwater snail Physa acuta was chosen to evaluate the potential deleterious effects of AgNP and counterpart AgNO3 , through water only exposures. AgNPs' toxicity is greatly influenced by medium composition. Thus, two test media were tested: Artificial Pond Water (APW) and modified APW (modified by removing calcium chloride from medium). Acute tests (96h) were performed with juvenile and adult snails, in both media, to assess lethality, and egg mass chronic tests, with APW medium only, to assess embryo viability and mortality, carried out until reaching 90% hatching success in the control. Acute toxicity increased with decreasing shell length for both silver forms (ion and nanoparticle), i.e. juveniles where more sensitive than adults. Different test media led to dissimilar LC50 values, with chloride playing an important role in toxicity, most probably by complexation with silver ions and thus reducing silver's bioavailability, uptake and toxicity. Chronic tests showed that hatching success was more sensitive to silver in the ionic form than in the particulate form. Different forms of silver, exposure media and life cycle stages led to different patterns of toxicity, highlighting an impairment in the snails' life cycle. This article is protected by copyright. All rights reserved.

Environmental pollution (Barking, Essex : 1987), Jan 17, 2016

Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different tr... more Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems - the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all teste...

Ecotoxicology and Environmental Safety, 2014

In aquatic ecosystems several stressors may act together and affect the life traits of organisms.... more In aquatic ecosystems several stressors may act together and affect the life traits of organisms. Pesticide runoffs are usually associated with high inputs of organic matter and depletion of oxygen in aquatic systems. This study aimed at combining anthropogenic stress (chemicals) and natural stress (food availability) and evaluates their joint effect to the life traits of Daphnia magna. The neonicotinoid insecticide imidacloprid and the heavy metal nickel chloride were used and a 21 d chronic test was carried out to obtain reproduction and growth data. The conceptual model Independent action, usually used for assessing response patterns in chemical mixtures, was used for data interpretation. Results showed an increase in the reproduction and growth pattern of D. magna as food levels increased. Both chemicals significantly impaired the reproduction as well as the somatic growth of the organism while the same happened with food concentrations lower than 3×10(5) cells/mL. It was also observed that food availability did not change the toxicity of imidacloprid and nickel chloride when food levels were higher than 3×10(5) cells/mL. When combined with low food levels, imidacloprid showed a slight increase in toxicity, showing that daphnids become more sensitive with reduced food availability, however in a non-significant way. However, toxicity of nickel appeared to be independent of the food level. Both chemicals induced mortality to the organisms exposed in the absence of food only at the end of the test.

Journal of Applied Toxicology, 2014

The persistent organic pollutant p,p&... more The persistent organic pollutant p,p'-DDE, the major metabolite of the insecticide DDT, has displayed evidence of endocrine disruption through the inhibition of androgen binding to androgen receptors in different species. Although p,p'-DDE was continuously detected in wild fish with abnormal gonad development such as intersex, little is known about its mode of action during gonad development in fish. To elucidate the potential endocrine effects of this pollutant in zebrafish (Danio rerio), juveniles (30 days post hatch) were exposed to p,p'-DDE during the critical window of sexual differentiation. Fish were exposed to sublethal concentrations ranging from 0.01 to 20 µg l(-1) over 14 days and were maintained in control water for an additional 4 months. As core endpoints, the vitellogenin (vtg) concentration was measured at the end of exposure, and sex ratio and the gonadosomatic index were assessed 4 months after the end of exposure. An increase in vtg production in whole body homogenate was observed in fish exposed to 0.2 and 2.0 µg l(-1) p,p'-DDE. No significant differences were displayed in morphological parameters such as the gonadosomatic index of males and females or sex ratio. However, exposed females presented histopathological changes that include the reduction of the number of mature oocytes, which might impair their successful reproduction. These results demonstrate the ability of p,p'-DDE to cause endocrine disruption in zebrafish exposed during gonad differentiation of juvenile specimens. Furthermore, vtg induction by p,p'-DDE in juvenile zebrafish arises as a predictive marker for adverse effects of this DDT metabolite on the ovarian function of female zebrafish. Copyright © 2014 John Wiley & Sons, Ltd.

Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, w... more Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, which potentiate their emission to the environment. The toxicity of Ag-NP has been associated with the release of Ag ions (Ag+), which are more toxic to aquatic organisms than Ag-NP. In this study, a toxicokinetics approach was applied to compare the potential of Daphnia magna to accumulate Ag from either Ag-NP or AgNO3 through different exposure routes: a) water, b) diet and c) water and diet. A one-compartment kinetics model was applied to describe the development of Ag body concentrations over time and derive uptake (k1w; k1d) and elimination (k2) rate constants. Under water-only exposure, AgNO3 induced higher Ag uptake rate constants and bioconcentration factors when compared to Ag-NP. For dietary exposure, no differences in Ag concentrations in D. magna, along with the kinetics parameters, were found for both Ag forms. Simultaneous water and dietary exposures to Ag-NP induced higher Ag concentrations in D. magna compared to AgNO3. In this combined exposure, uptake from water explains most for the increase in Ag body concentration in D. magna for Ag-NP exposure, whereas uptake from the diet was the major contributor for the increase in Ag concentration in D. magna under AgNO3 exposure. Biomagnification was not observed for any of the exposure routes applied in this study, neither for Ag-NP nor for AgNO3.

Silver nanoparticles (AgNPs) are widely used worldwide, most likely leading to their release into... more Silver nanoparticles (AgNPs) are widely used worldwide, most likely leading to their release into the environment and a subsequent increase of environmental concentrations. Studies of their deleterious effects on organisms is crucial to understand their environmental impacts. The freshwater snail Physa acuta was chosen to evaluate the potential deleterious effects of AgNPs and their counterpart AgNO3, through water-only exposures. The toxicity of AgNPs is greatly influenced by medium composition. Thus, 2 media were tested: artificial pond water (APW) and modified APW (adapted by removing calcium chloride). Acute tests (96 h) were performed with juvenile and adult snails in both media to assess lethality, and egg mass chronic tests were conducted with APW medium only to assess embryo viability and mortality, carried out until 90% hatching success was reached in the control. Acute toxicity increased with decreasing shell length for both silver forms (ion and nanoparticle); that is, juveniles were more sensitive than adults. Different test media led to dissimilar median lethal concentrations, with chloride playing an important role in toxicity, most likely by complexation with silver ions, which would reduce the bioavailability, uptake, and toxicity of silver. Chronic tests showed that hatching success was more sensitive to silver in the ionic form than in the particulate form. Different forms of silver, exposure media, and life cycle stages led to different patterns of toxicity, highlighting an impairment in the snails’ life cycle.

Marine and estuarine ecosystems are highly productive areas that often act as a final sink for se... more Marine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd2+ ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd2+ ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd2+ speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of 7.5, while depuration rate fluctuated, thus suggesting that both parameters are mediated by metabolic processes (to maintain homeostasis at pH levels lower than normal) and ion competition at membrane binding sites. Cadmium concentration in A. tonsa, uptake and depuration rates increased with increasing temperature, a trend that can be attributed to an increase in metabolic energy demand at higher temperatures. The present study shows that cadmium uptake and depuration rates in the marine copepod A. tonsa is mostly affected by biological processes, mainly driven by metabolic mechanisms, and to a lesser extent by metal speciation in the exposure medium.

Journal of Applied Toxicology, 2014

Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different tr... more Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems – the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all tested species. Recorded cadmium toxicity was (by increasing order): S. senegalensis eggs < P. varians post-larvae < P. varians zoea I < S. senegalensis larvae < A. tonsa eggs < A. tonsa LDR. DNA damage to all species exposed to cadmium increased with increasing concentrations. Overall, understanding cadmium chemical speciation is paramount to reliably evaluate the effects of this metal in marine ecosystems. Cadmium is genotoxic to all three species tested and therefore may differentially impact individuals and populations of marine taxa. As A. tonsa was the most sensitive species and occupies a lower trophic level, it is likely that cadmium contamination may trigger bottom-up cascading effects in marine trophic interactions.

The persistent organic pollutant p,p′-DDE, the major metabolite of the insecticide DDT, has displ... more The persistent organic pollutant p,p′-DDE, the major metabolite of the insecticide DDT, has displayed evidence of endocrine disruption through the inhibition of androgen binding to androgen receptors in different species. Although p,p′-DDE was continuously detected in wild fish with abnormal gonad development such as intersex, little is known about its mode of action during gonad development in fish. To elucidate the potential endocrine effects of this pollutant in zebrafish (Danio rerio), juveniles (30 days post hatch) were exposed to p,p′-DDE during the critical window of sexual differentiation. Fish were exposed to sublethal concentrations ranging from 0.01 to 20 µg l–1 over 14 days and were maintained in control water for an additional 4 months. As core endpoints, the vitellogenin (vtg) concentration was measured at the end of exposure, and sex ratio and the gonadosomatic index were assessed 4 months after the end of exposure. An increase in vtg production in whole body homogenate was observed in fish exposed to 0.2 and 2.0 µg l–1 p,p′-DDE. No significant differences were displayed in morphological parameters such as the gonadosomatic index of males and females or sex ratio. However, exposed females presented histopathological changes that include the reduction of the number of mature oocytes, which might impair their successful reproduction. These results demonstrate the ability of p,p′-DDE to cause endocrine disruption in zebrafish exposed during gonad differentiation of juvenile specimens. Furthermore, vtg induction by p,p′-DDE in juvenile zebrafish arises as a predictive marker for adverse effects of this DDT metabolite on the ovarian function of female zebrafish. Copyright © 2014 John Wiley & Sons, Ltd.

… and environmental safety, Jan 1, 2010

Water

Bioaccumulation of cadmium was assessed in different tissues of the benthic fish Solea senegalens... more Bioaccumulation of cadmium was assessed in different tissues of the benthic fish Solea senegalensis. Juvenile Senegalese soles were simultaneously exposed to cadmium-contaminated diet (Hediste diversicolor) and water during 14 days and allowed to depurate for another 14 days. Cadmium content was measured in muscle, gills, liver and intestine, with recorded values increasing in these tissues in this same order. Muscle showed a considerably lower cadmium accumulation after 14 days of uptake. Cadmium kinetics in juvenile Senegalese soles revealed that the highest uptake flux of this metal occurred in the intestine. Cadmium depuration from the liver was not detected, which suggests the existence of a storage compartment for this metal in Solea senegalensis during uptake and depuration. Comparisons between maximum acceptable values for cadmium in the muscle, the Target Hazard Quotient and the Estimated Weekly Intake, indicated that acceptable limits were not exceeded, and the muscle of j...

Environmental Toxicology and Chemistry

The present study assessed cadmium uptake and depuration rates in the euryhaline estuarine shrimp... more The present study assessed cadmium uptake and depuration rates in the euryhaline estuarine shrimp Palaemon varians under different exposure routes. Postlarval shrimp were exposed for 4 d under different exposure routes: contaminated water, contaminated diet, and a 2-way exposure scenario where both contaminated water and diet were used. After exposure, postlarval shrimp were transferred to a clean medium and fed a noncontaminated diet for 96 h. Bioaccumulation via the different exposure routes was modeled with a standard first-order, one-compartment toxicokinetics model and one with an additional parameter reflecting an inert fraction or storage compartment. The simultaneous 2-way exposure (through water and diet) resulted in accumulation being almost twice as high as the sum of the individual exposure routes, thus indicating that accumulation from multiple routes may be more than additive. Cadmium uptake from water was faster than uptake from food maintained for 48 h at that same cadmium concentration. Shrimp were unable to eliminate cadmium from their body, showing no depuration during 96 h after exposure via different routes, thus suggesting that a longer depuration period is needed. Model comparisons did not provide a significantly better fit when the model included the presence of an inert fraction. The present study highlights the importance of assessing accumulation using multiple exposure routes compared with individual routes because the latter may underestimate bioaccumulation. Environ Toxicol Chem 2018;37:1614-1622. © 2018 SETAC.

Ecotoxicology and environmental safety, Jan 18, 2017

mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for s... more mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd(2+) ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd(2+) ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd(2+) speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of ...

Science of The Total Environment, 2016

Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, w... more Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, which potentiate their emission to the environment. The toxicity of Ag-NP has been associated with the release of Ag ions (Ag(+)), which are more toxic to aquatic organisms than Ag-NP. In this study, a toxicokinetics approach was applied to compare the potential of Daphnia magna to accumulate Ag from either Ag-NP or AgNO3 through different exposure routes: a) water, b) diet and c) water and diet. A one-compartment kinetics model was applied to describe the development of Ag body concentrations over time and derive uptake (k1w; k1d) and elimination (k2) rate constants. Under water-only exposure, AgNO3 induced higher Ag uptake rate constants and bioconcentration factors when compared to Ag-NP. For dietary exposure, no differences in Ag concentrations in D. magna, along with the kinetics parameters, were found for both Ag forms. Simultaneous water and dietary exposures to Ag-NP induced higher Ag concentrations in D. magna compared to AgNO3. In this combined exposure, uptake from water explains most for the increase in Ag body concentration in D. magna for Ag-NP exposure, whereas uptake from the diet was the major contributor for the increase in Ag concentration in D. magna under AgNO3 exposure. Biomagnification was not observed for any of the exposure routes applied in this study, neither for Ag-NP nor for AgNO3.

Environmental Toxicology and Chemistry, 2016

Silver nanoparticles (AgNP) are highly used worldwide, which will most likely lead to their relea... more Silver nanoparticles (AgNP) are highly used worldwide, which will most likely lead to their release to the environment and subsequently increase environmental concentrations. Therefore studying AgNPs&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; deleterious effects to organisms is crucial to understand their environmental impacts. The freshwater snail Physa acuta was chosen to evaluate the potential deleterious effects of AgNP and counterpart AgNO3 , through water only exposures. AgNPs&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; toxicity is greatly influenced by medium composition. Thus, two test media were tested: Artificial Pond Water (APW) and modified APW (modified by removing calcium chloride from medium). Acute tests (96h) were performed with juvenile and adult snails, in both media, to assess lethality, and egg mass chronic tests, with APW medium only, to assess embryo viability and mortality, carried out until reaching 90% hatching success in the control. Acute toxicity increased with decreasing shell length for both silver forms (ion and nanoparticle), i.e. juveniles where more sensitive than adults. Different test media led to dissimilar LC50 values, with chloride playing an important role in toxicity, most probably by complexation with silver ions and thus reducing silver&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s bioavailability, uptake and toxicity. Chronic tests showed that hatching success was more sensitive to silver in the ionic form than in the particulate form. Different forms of silver, exposure media and life cycle stages led to different patterns of toxicity, highlighting an impairment in the snails&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; life cycle. This article is protected by copyright. All rights reserved.

Environmental pollution (Barking, Essex : 1987), Jan 17, 2016

Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different tr... more Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems - the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all teste...

Ecotoxicology and Environmental Safety, 2014

In aquatic ecosystems several stressors may act together and affect the life traits of organisms.... more In aquatic ecosystems several stressors may act together and affect the life traits of organisms. Pesticide runoffs are usually associated with high inputs of organic matter and depletion of oxygen in aquatic systems. This study aimed at combining anthropogenic stress (chemicals) and natural stress (food availability) and evaluates their joint effect to the life traits of Daphnia magna. The neonicotinoid insecticide imidacloprid and the heavy metal nickel chloride were used and a 21 d chronic test was carried out to obtain reproduction and growth data. The conceptual model Independent action, usually used for assessing response patterns in chemical mixtures, was used for data interpretation. Results showed an increase in the reproduction and growth pattern of D. magna as food levels increased. Both chemicals significantly impaired the reproduction as well as the somatic growth of the organism while the same happened with food concentrations lower than 3×10(5) cells/mL. It was also observed that food availability did not change the toxicity of imidacloprid and nickel chloride when food levels were higher than 3×10(5) cells/mL. When combined with low food levels, imidacloprid showed a slight increase in toxicity, showing that daphnids become more sensitive with reduced food availability, however in a non-significant way. However, toxicity of nickel appeared to be independent of the food level. Both chemicals induced mortality to the organisms exposed in the absence of food only at the end of the test.

Journal of Applied Toxicology, 2014

The persistent organic pollutant p,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;... more The persistent organic pollutant p,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-DDE, the major metabolite of the insecticide DDT, has displayed evidence of endocrine disruption through the inhibition of androgen binding to androgen receptors in different species. Although p,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-DDE was continuously detected in wild fish with abnormal gonad development such as intersex, little is known about its mode of action during gonad development in fish. To elucidate the potential endocrine effects of this pollutant in zebrafish (Danio rerio), juveniles (30 days post hatch) were exposed to p,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-DDE during the critical window of sexual differentiation. Fish were exposed to sublethal concentrations ranging from 0.01 to 20 µg l(-1) over 14 days and were maintained in control water for an additional 4 months. As core endpoints, the vitellogenin (vtg) concentration was measured at the end of exposure, and sex ratio and the gonadosomatic index were assessed 4 months after the end of exposure. An increase in vtg production in whole body homogenate was observed in fish exposed to 0.2 and 2.0 µg l(-1) p,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-DDE. No significant differences were displayed in morphological parameters such as the gonadosomatic index of males and females or sex ratio. However, exposed females presented histopathological changes that include the reduction of the number of mature oocytes, which might impair their successful reproduction. These results demonstrate the ability of p,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-DDE to cause endocrine disruption in zebrafish exposed during gonad differentiation of juvenile specimens. Furthermore, vtg induction by p,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-DDE in juvenile zebrafish arises as a predictive marker for adverse effects of this DDT metabolite on the ovarian function of female zebrafish. Copyright © 2014 John Wiley &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Sons, Ltd.

Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, w... more Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, which potentiate their emission to the environment. The toxicity of Ag-NP has been associated with the release of Ag ions (Ag+), which are more toxic to aquatic organisms than Ag-NP. In this study, a toxicokinetics approach was applied to compare the potential of Daphnia magna to accumulate Ag from either Ag-NP or AgNO3 through different exposure routes: a) water, b) diet and c) water and diet. A one-compartment kinetics model was applied to describe the development of Ag body concentrations over time and derive uptake (k1w; k1d) and elimination (k2) rate constants. Under water-only exposure, AgNO3 induced higher Ag uptake rate constants and bioconcentration factors when compared to Ag-NP. For dietary exposure, no differences in Ag concentrations in D. magna, along with the kinetics parameters, were found for both Ag forms. Simultaneous water and dietary exposures to Ag-NP induced higher Ag concentrations in D. magna compared to AgNO3. In this combined exposure, uptake from water explains most for the increase in Ag body concentration in D. magna for Ag-NP exposure, whereas uptake from the diet was the major contributor for the increase in Ag concentration in D. magna under AgNO3 exposure. Biomagnification was not observed for any of the exposure routes applied in this study, neither for Ag-NP nor for AgNO3.

Silver nanoparticles (AgNPs) are widely used worldwide, most likely leading to their release into... more Silver nanoparticles (AgNPs) are widely used worldwide, most likely leading to their release into the environment and a subsequent increase of environmental concentrations. Studies of their deleterious effects on organisms is crucial to understand their environmental impacts. The freshwater snail Physa acuta was chosen to evaluate the potential deleterious effects of AgNPs and their counterpart AgNO3, through water-only exposures. The toxicity of AgNPs is greatly influenced by medium composition. Thus, 2 media were tested: artificial pond water (APW) and modified APW (adapted by removing calcium chloride). Acute tests (96 h) were performed with juvenile and adult snails in both media to assess lethality, and egg mass chronic tests were conducted with APW medium only to assess embryo viability and mortality, carried out until 90% hatching success was reached in the control. Acute toxicity increased with decreasing shell length for both silver forms (ion and nanoparticle); that is, juveniles were more sensitive than adults. Different test media led to dissimilar median lethal concentrations, with chloride playing an important role in toxicity, most likely by complexation with silver ions, which would reduce the bioavailability, uptake, and toxicity of silver. Chronic tests showed that hatching success was more sensitive to silver in the ionic form than in the particulate form. Different forms of silver, exposure media, and life cycle stages led to different patterns of toxicity, highlighting an impairment in the snails’ life cycle.

Marine and estuarine ecosystems are highly productive areas that often act as a final sink for se... more Marine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd2+ ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd2+ ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd2+ speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of 7.5, while depuration rate fluctuated, thus suggesting that both parameters are mediated by metabolic processes (to maintain homeostasis at pH levels lower than normal) and ion competition at membrane binding sites. Cadmium concentration in A. tonsa, uptake and depuration rates increased with increasing temperature, a trend that can be attributed to an increase in metabolic energy demand at higher temperatures. The present study shows that cadmium uptake and depuration rates in the marine copepod A. tonsa is mostly affected by biological processes, mainly driven by metabolic mechanisms, and to a lesser extent by metal speciation in the exposure medium.

Journal of Applied Toxicology, 2014

Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different tr... more Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems – the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all tested species. Recorded cadmium toxicity was (by increasing order): S. senegalensis eggs < P. varians post-larvae < P. varians zoea I < S. senegalensis larvae < A. tonsa eggs < A. tonsa LDR. DNA damage to all species exposed to cadmium increased with increasing concentrations. Overall, understanding cadmium chemical speciation is paramount to reliably evaluate the effects of this metal in marine ecosystems. Cadmium is genotoxic to all three species tested and therefore may differentially impact individuals and populations of marine taxa. As A. tonsa was the most sensitive species and occupies a lower trophic level, it is likely that cadmium contamination may trigger bottom-up cascading effects in marine trophic interactions.

The persistent organic pollutant p,p′-DDE, the major metabolite of the insecticide DDT, has displ... more The persistent organic pollutant p,p′-DDE, the major metabolite of the insecticide DDT, has displayed evidence of endocrine disruption through the inhibition of androgen binding to androgen receptors in different species. Although p,p′-DDE was continuously detected in wild fish with abnormal gonad development such as intersex, little is known about its mode of action during gonad development in fish. To elucidate the potential endocrine effects of this pollutant in zebrafish (Danio rerio), juveniles (30 days post hatch) were exposed to p,p′-DDE during the critical window of sexual differentiation. Fish were exposed to sublethal concentrations ranging from 0.01 to 20 µg l–1 over 14 days and were maintained in control water for an additional 4 months. As core endpoints, the vitellogenin (vtg) concentration was measured at the end of exposure, and sex ratio and the gonadosomatic index were assessed 4 months after the end of exposure. An increase in vtg production in whole body homogenate was observed in fish exposed to 0.2 and 2.0 µg l–1 p,p′-DDE. No significant differences were displayed in morphological parameters such as the gonadosomatic index of males and females or sex ratio. However, exposed females presented histopathological changes that include the reduction of the number of mature oocytes, which might impair their successful reproduction. These results demonstrate the ability of p,p′-DDE to cause endocrine disruption in zebrafish exposed during gonad differentiation of juvenile specimens. Furthermore, vtg induction by p,p′-DDE in juvenile zebrafish arises as a predictive marker for adverse effects of this DDT metabolite on the ovarian function of female zebrafish. Copyright © 2014 John Wiley & Sons, Ltd.

… and environmental safety, Jan 1, 2010