Posts Tagged 'toxicants'

The effect of pH on the acute toxicity of phenanthrene in a marine microalgae Chlorella salina

Phenanthrene is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) found in continental shelf environment of China and is on the EPA’s Priority Pollutant list. In this study, the effects of phenanthrene on marine algal growth rate were determined after 96-h exposure at pH 6.0, 7.0, 8.0, 9.0, and 10.0 in seawater of salinity 35. Two measuring techniques to assess growth inhibition were also compared using prompt fluorescence and microscopic cell count. The results showed that the toxicity of phenanthrene increased significantly (p < 0.05) with decreasing pH, with the nominal concentration required to inhibit growth rate by 50%, EC50, decreasing from 1.893 to 0.237 mg L−1 as pH decreased from 9.0 to 6.0, with a decrease higher than 55% from 10.0 to 9.0. In addition, the nominal EC50 values calculated in this study were at the same range of some environmental concentrations of phenanthrene close to areas of crude oil exploration. Based on the two measuring techniques, the results showed that cell count and fluorescence measurement were significantly different (p < 0.05), and the nominal EC50 values calculated with cell count measurement were significantly higher than fluorescence measurement at pH 8.0, 9.0 and 10.0. In conclusion, the present studies confirmed that acidification of seawater could affect the toxicity of phenanthrene to this species of microalgae, and which encouraged further studies involving responses of marine organisms to ocean acidification.

Continue reading ‘The effect of pH on the acute toxicity of phenanthrene in a marine microalgae Chlorella salina’

Genotoxic effects of combined multiple stressors on Gammarus locusta haemocytes: Interactions between temperature, pCO2 and the synthetic progestin levonorgestrel

Highlights

• Combined factors (temperature, pCO2, levonorgestrel) were assessed on G. locusta.

• Comet assay as valid technique to evaluate DNA damage in haemocytes.

• Haemocytes of each treatment were exposed, ex vivo, to an oxidant agent – H2O2.

• Stress factors alone did not significantly increase DNA damage, after 21 days.

• Solvent increased haemocytes DNA damage – not observed in hormone treatments.

Abstract

Climate change and pharmaceutical contamination are two priority research topics due to their impacts in the aquatic ecosystems and in the food chain structure. In the bottom of many food chains are the invertebrates, like the amphipods, which are important environmental and ecotoxicological models. In this study, we combined the increase of temperature [ambient and warming temperature], pCO2 [normocapnia and hypercapnia] and the synthetic progestin levonorgestrel (LNG) [environmentally relevant concentration (10 ng L−1) and 100-fold higher (1000 ng L−1)] to evaluate the genotoxic effects on the amphipod Gammarus locusta haemocytes, using the comet assay technique. Additionally, the study examined protective/potentiating effects of the three tested factors against hydrogen peroxide (H2O2)-induced DNA damage in haemocytes after ex vivo exposure. Our data revealed no significant effects of any of the three stressors on DNA damage of G. locusta haemocytes or protection against H2O2-induced DNA damage after twenty-one days exposure. Only a significant effect of the solvent was visible, since it was able to induce higher DNA damage (i.e. strand breaks) on exposed individuals. On the other hand, LNG exposure seemed to induce a slight increase of DNA damage after H2O2 exposure. Our findings suggest that more short-term studies to conclude about the genotoxicity and/or protective effects of the stress factors in G. locusta should be made, attending to the fast turnover rate of repairing cells that could have masked impacts seen only after the end of the experiment.

Cruzeiro C., Ramos A., Loganimoce E. M., Arenas F., Rocha E. & Cardoso P. G., 2019. Genotoxic effects of combined multiple stressors on Gammarus locusta haemocytes: Interactions between temperature, pCO2 and the synthetic progestin levonorgestrel. Environmental Pollution 245: 864-872. Article (subscription required).

Effects of oil and global environmental drivers on two keystone marine invertebrates

Ocean warming (OW) and acidification (OA) are key features of global change and are predicted to have negative consequences for marine species and ecosystems. At a smaller scale increasing oil and gas activities at northern high latitudes could lead to greater risk of petroleum pollution, potentially exacerbating the effects of such global stressors. However, knowledge of combined effects is limited. This study employed a scenario-based, collapsed design to investigate the impact of one local acute stressor (North Sea crude oil) and two chronic global drivers (pH for OA and temperature for OW), alone or in combination on aspects of the biology of larval stages of two key invertebrates: the northern shrimp (Pandalus borealis) and the green sea urchin (Strongylocentrotus droebachiensis). Both local and global drivers had negative effects on survival, development and growth of the larval stages. These effects were species- and stage-dependent. No statistical interactions were observed between local and global drivers and the combined effects of the two drivers were approximately equal to the sum of their separate effects. This study highlights the importance of adjusting regulation associated with oil spill prevention to maximize the resilience of marine organisms to predicted future global conditions.

Continue reading ‘Effects of oil and global environmental drivers on two keystone marine invertebrates’

Bioaccumulation and ecotoxicological responses of juvenile white seabream (Diplodus sargus) exposed to triclosan, warming and acidification

Highlights

• TCS was primarily bioaccumulated by fish muscle, followed by liver and brain.
• Climate change significantly reduced TCS bioaccumulation in all fish tissues.
• TCS and TCS + acidification increased LPO and inhibited HSP70/HSC70 synthesis.
• AChE activity was inhibited by TCS alone or combined with both abiotic stressors.
• VTG content was further diminished by TCS co-exposed with both abiotic stressors.

Abstract

Triclosan (TCS) is a synthetic microbial compound widely used in the formulation of various personal care products. Its frequent detection in marine ecosystems, along with its physical and chemical properties, suggest that TCS can be highly persistent, being easily bioaccumulated by biota and, therefore, eliciting various toxicological responses. Yet, TCS’s mechanisms of bioaccumulation and toxicity still deserve further research, particularly focusing on the interactive effects with climate change-related stressors (e.g. warming and acidification), as both TCS chemical behaviour and marine species metabolism/physiology can be strongly influenced by the surrounding abiotic conditions. Hence, the aim of this study was to assess TCS bioaccumulation and ecotoxicological effects (i.e. animal fitness indexes, antioxidant activity, protein chaperoning and degradation, neurotoxicity and endocrine disruption) in three tissues (i.e. brain, liver and muscle) of juvenile Diplodus sargus exposed to the interactive effects of TCS dietary exposure (15.9 μg kg−1 dw), seawater warming (ΔTºC = +5 °C) and acidification (ΔpCO2 ∼ +1000 μatm, equivalent to ΔpH = −0.4 units). Muscle was the primary organ of TCS bioaccumulation, and climate change stressors, particularly warming, significantly reduced TCS bioaccumulation in all fish tissues. Furthermore, the negative ecotoxicological responses elicited by TCS were significantly altered by the co-exposure to acidification and/or warming, through either the enhancement (e.g. vitellogenin content) or counteraction/inhibition (e.g. heat shock proteins HSP70/HSC70 content) of molecular biomarker responses, with the combination of TCS plus acidification resulting in more severe alterations. Thus, the distinct patterns of TCS tissue bioaccumulation and ecotoxicological responses induced by the different scenarios emphasized the need to further understand the interactive effects between pollutants and abiotic conditions, as such knowledge enables a better estimation and mitigation of the toxicological impacts of climate change in marine ecosystems.

Continue reading ‘Bioaccumulation and ecotoxicological responses of juvenile white seabream (Diplodus sargus) exposed to triclosan, warming and acidification’

Living in a multi-stressors environment: an integrated biomarker approach to assess the ecotoxicological response of meagre (Argyrosomus regius) to venlafaxine, warming and acidification

Highlights
• VFX toxicity was influenced by exposure route, as well as by abiotic stressors
• VFX water exposure induced more severe biomarker responses than VFX feed exposure
• Muscle, liver and brain biomarker responses were significantly affected by warming
• Biomarker changes due to acidification were more evident in fish gills
• The combination of the three stressors simultaneously increased stress severity
• The importance of assessing potential interaction between stressors was evidenced

Abstract
Pharmaceuticals, such as the antidepressant venlafaxine (VFX), have been frequently detected in coastal waters and marine biota, and there is a growing body of evidence that these pollutants can be toxic to non-target marine biota, even at low concentrations. Alongside, climate change effects (e.g. warming and acidification) can also affect marine species’ physiological fitness and, consequently, compromising their ability to cope with the presence of pollutants. Yet, information regarding interactive effects between pollutants and climate change-related stressors is still scarce. Within this context, the present study aims to assess the differential ecotoxicological responses (antioxidant activity, heat shock response, protein degradation, endocrine disruption and neurotoxicity) of juvenile fish (Argyrosomus regius) tissues (muscle, gills, liver and brain) exposed to VFX (via water or feed), as well as to the interactive effects of warming (ΔT°C = +5 °C) and acidification (ΔpCO2 ~ +1000 µatm, equivalent to ΔpH = −0.4 units), using an integrated multi-biomarker response (IBR) approach.

Overall, results showed that VFX toxicity was strongly influenced by the uptake pathway, as well as by warming and acidification. More significant changes (e.g. increases surpassing 100% in lipid peroxidation, LPO, heat shock response protein content, HSP70/HSC70, and total ubiquitin content, Ub,) and higher IBR index values were observed when VFX exposure occurred via water (i.e. average IBR = 19, against 17 in VFX-feed treatment). The co-exposure to climate change-related stressors either enhanced (e.g. glutathione S-transferases activity (GST) in fish muscle was further increased by warming) or attenuated the changes elicited by VFX (e.g. vitellogenin, VTG, liver content increased with VFX feed exposure acting alone, but not when co-exposed with acidification). Yet, increased stress severity was observed when the three stressors acted simultaneously, particularly in fish exposed to VFX via water (i.e. average IBR = 21). Hence, the distinct fish tissues responses elicited by the different scenarios emphasized the relevance of performing multi-stressors ecotoxicological studies, as such approach enables a better estimation of the environmental hazards posed by pollutants in a changing ocean and, consequently, the development of strategies to mitigate them.

Continue reading ‘Living in a multi-stressors environment: an integrated biomarker approach to assess the ecotoxicological response of meagre (Argyrosomus regius) to venlafaxine, warming and acidification’

The health risk for seafood consumers under future ocean acidification (OA) scenarios: OA alters bioaccumulation of three pollutants in an edible bivalve species through affecting the in vivo metabolism

Highlights

• OA increased B[a]P accumulation in blood clams.
• OA decreased the accumulation of NFZ and CAP in blood clams.
• Health risks increased for B[a]P but not for NFZ & CAP.
• Changes in accumulation may be due to altered eliminating ability.

Abstract

The current knowledge about the effect of pCO2-driven ocean acidification on the bioaccumulation of pollutants in marine species is still scarce, as only limited types of pollutants have been investigated. Therefore, to obtain a better understanding of the effect of ocean acidification on the process of bioaccumulation and subsequent food safety, the accumulation of benzo[a]pyrene (B[a]P), chloramphenicol (CAP), and nitrofurazone (NFZ) in an edible bivalve species, Tegillarca granosa, under present and near-future ocean acidification scenarios was investigated in the present study. The health risks associated with consuming contaminated blood clams were also assessed using target hazard quotient (THQ), lifetime cancer risk (CR), or margin of exposure (MoE). To explain the alterations in bioaccumulation of these pollutants, the expressions of genes encoding corresponding key metabolic proteins were analyzed as well. The results obtained showed that ocean acidification exerted a significant effect on the accumulation of B[a]P, NFZ, and CAP in the clams. After four-week exposure to B[a]P, NFZ, or CAP contaminated seawater acidified with CO2 at pH 7.8 and 7.4, significantly greater amounts of B[a]P and lower amounts of NFZ and CAP were accumulated in the clams compared to that in the control. Although no non-carcinogenic risk of consuming B[a]P-contaminated blood clams was detected using the THQ values obtained, the CR values obtained indicated a high life-time risk in all groups. In addition, according to the MoE values obtained, the health risks in terms of consuming NFZ- and CAP-contaminated clams were significantly reduced under ocean acidification scenarios but still cannot be ignored, especially for children. The gene expression results showed that the ability of clams to eliminate B[a]P may be significantly constrained, whereas the ability to eliminate NFZ and CAP may be enhanced under ocean acidification scenarios, indicating that the changes in the accumulation of these pollutants may be due to the altered in vivo metabolism.

Continue reading ‘The health risk for seafood consumers under future ocean acidification (OA) scenarios: OA alters bioaccumulation of three pollutants in an edible bivalve species through affecting the in vivo metabolism’

Development of the sea urchin Heliocidaris crassispina from Hong Kong is robust to ocean acidification and copper contamination

Highlights

• Ocean acidification will increase the fraction of the most toxic form of copper, increasing its bioavailability to marine organisms
• We tested the hypothesis that copper contaminated waters are more toxic to sea urchin larvae under future pH conditions in three laboratory experiments
• Larvae are robust to the pH and the copper levels we tested (little/no mortality)
• However, significant sub-lethal effects, could have indirect consequences on survival

Abstract

Metallic pollution is of particular concern in coastal cities. In the Asian megacity of Hong Kong, despite water qualities have improved over the past decade, some local zones are still particularly affected and could represent sinks for remobilization of labile toxic species such as copper. Ocean acidification is expected to increase the fraction of the most toxic form of copper (Cu2+) by 2.3-folds by 2100 (pH ≈7.7), increasing its bioavailability to marine organisms. Multiple stressors are likely to exert concomitant effects (additive, synergic or antagonist) on marine organisms.

Here, we tested the hypothesis that copper contaminated waters are more toxic to sea urchin larvae under future pH conditions. We exposed sea urchin embryos and larvae to two low-pH and two copper treatments (0.1 and 1.0 μM) in three separate experiments. Over the short time typically used for toxicity tests (up to 4-arm plutei, i.e. 3 days), larvae of the sea urchin Heliocidaris crassispina were robust and survived the copper levels present in Hong Kong waters today (≤0.19 μM) as well as the average pH projected for 2100. We, however, observed significant mortality with lowering pH in the longer, single-stressor experiment (Expt A: 8-arm plutei, i.e. 9 days). Abnormality and arm asymmetry were significantly increased by pH or/and by copper presence (depending on the experiment and copper level). Body size (d3; but not body growth rates in Expt A) was significantly reduced by both lowered pH and added copper. Larval respiration (Expt A) was doubled by a decrease at pHT from 8.0 to 7.3 on d6. In Expt B1.0 and B0.1, larval morphology (relative arm lengths and stomach volume) were affected by at least one of the two investigated factors.

Although the larvae appeared robust, these sub-lethal effects may have indirect consequences on feeding, swimming and ultimately survival. The complex relationship between pH and metal speciation/uptake is not well-characterized and further investigations are urgently needed to detangle the mechanisms involved and to identify possible caveats in routinely used toxicity tests.

Continue reading ‘Development of the sea urchin Heliocidaris crassispina from Hong Kong is robust to ocean acidification and copper contamination’


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