Posts Tagged 'toxicants'

Physiological responses of corals to ocean acidification and copper exposure

Highlights

  • Differences in copper accumulation and sensitivity were observed between coral species and between coral and zooxanthellae
  • Increased CO2 did not influence copper accumulation
  • Synergistic effects from combined CO2 and copper exposure were observed in corals
  • Altered enzyme activity was observed in both coral exposed to copper or CO2
  • A. cervicornis was more affected by copper and P. damicornis was more affected by increased CO2

Abstract

Acidification and land-based sources of pollution have been linked to widespread declines of coral cover in coastal reef ecosystems. In this study, two coral species, Acropora cervicornis and Pocillopora damicornis were exposed to increased copper at two CO2 levels for 96 h. Copper accumulation and anti-oxidant enzyme activities were measured. Copper accumulation only increased in A. cervicornis zooxanthellae and corresponded with photosynthetic toxicity. Enzyme activities in both coral species were affected; however, A. cervicornis was more sensitive than P. damicornis, and zooxanthellae were more affected than animal fractions of holobionts. Generally, activities of all anti-oxidant enzymes increased, with copper exposure in corals; whereas, activities of glutathione reductase and to some degree glutathione peroxidase were observed due to increasing CO2 exposure alone. Exposure to copper in combination with higher CO2 resulted in a synergistic response in some cases. These results provide insight into mechanisms of copper and CO2 impacts in corals.

Continue reading ‘Physiological responses of corals to ocean acidification and copper exposure’

Integrated multi-biomarker responses of juvenile seabass to diclofenac, warming and acidification co-exposure

Highlights

• An integrated multi-biomarker approach was used to assess ecotoxicological responses of D. labrax under the co-exposure to DCF, warming and acidification.
• DCF decreased HSI, BBratio, erythrocyte viability and HSP70/HSC70 content in fish brain.
• DCF induced ENAs, oxidative stress, Ub synthesis in muscle, brain AChE activity and liver VTG synthesis.
• DCF deleterious effects were either enhanced or reversed/inhibited by the co-exposure to acidification and/or warming.
• IBR showed that DCF and warming co-exposure resulted in an overall higher degree of stress.
• Results highlighted the need to consider interactions between different stressors in future ecotoxicological studies.

Abstract

Pharmaceutical drugs, such as diclofenac (DCF), are frequently detected in the marine environment, and recent evidence has pointed out their toxicity to non-target marine biota. Concomitantly, altered environmental conditions associated with climate change (e.g. warming and acidification) can also affect the physiology of marine organisms. Yet, the underlying interactions between these environmental stressors (pharmaceutical exposure and climate change-related stressors) still require a deeper understanding. Comprehending the influence of abiotic variables on chemical contaminants’ toxicological attributes provides a broader view of the ecological consequences of climate change. Hence, the aim of this study was to assess the ecotoxicological responses of juvenile seabass Dicenthrachus labrax under the co-exposure to DCF (from dietary sources, 500 ± 36 ng kg-1 dw), warming (ΔTºC = +5 °C) and acidification (ΔpCO2 ~1000 µatm, equivalent to ΔpH = -0.4 units), using an “Integrated Biomarker Response” (IBR) approach. Fish were exposed to these three stressors, acting alone or combined, for 28 days in a full cross-factorial design, and blood, brain, liver and muscle tissues were subsequently collected in order to evaluate: i) animal/organ fitness; ii) hematological parameters and iii) molecular biomarkers. Results not only confirmed the toxicological attributes of dietary exposure to DCF in marine fish species at the tissue (e.g. lower HSI), cellular (e.g. increased ENAs and lower erythrocytes viability) and molecular levels (e.g. increased oxidative stress, protein degradation, AChE activity and VTG synthesis), but also showed that such attributes are altered by warming and acidification. Hence, while acidification and/or warming enhanced some effects of DCF exposure (e.g. by further lowering erythrocyte viability, and increasing brain GST activity and Ub synthesis in muscle), the co-exposure to these abiotic stressors also resulted in a reversion/inhibition of some molecular responses (e.g. lower CAT and SOD inhibition and VTG synthesis). IBRs evidenced that an overall higher degree of stress (i.e. high IBR index) was associated with DCF and warming co-exposure, while the effects of acidification were less evident. The distinct responses observed when DCF acted alone or the animals were co-exposed to the drug together with warming and acidification not only highlighted the relevance of considering the interactions between multiple environmental stressors in ecotoxicological studies, but also suggested that the toxicity of pharmaceuticals can be aggravated by climate change-related stressors (particularly warming), thus, posing additional biological challenges to marine fish populations.

Continue reading ‘Integrated multi-biomarker responses of juvenile seabass to diclofenac, warming and acidification co-exposure’

Does exposure to reduced pH and diclofenac induce oxidative stress in marine bivalves? A comparative study with the mussel Mytilus galloprovincialis and the clam Ruditapes philippinarum

Highlights
• Combined effects of seawater acidification and diclofenac are assessed in bivalves.
• Biochemical parameters were more influenced by reduced pH than by diclofenac.
• Lowered pH induced oxidative stress in M. galloprovincialis and R. philippinarum.
• Lowered pH reduced COX activity in of R. philippinarum.
R. philippinarum is more vulnerable to acidification than M. galloprovincialis.

Abstract
CO2-driven acidification and emerging contaminants, such as pharmaceuticals, pose new threats for the maintenance of natural populations of marine organisms by interfering with their normal biochemical pathways and defences. The combined effects of seawater acidification, as predicted in climate change scenarios, and an emerging contaminant (the non-steroidal anti-inflammatory drug, NSAID, diclofenac) on oxidative stress-related parameters were investigated in the Mediterranean mussel Mytilus galloprovincialis and the Manila clam Ruditapes philippinarum. A flow-through system was used to carry out a three-week exposure experiment with the bivalves. First, the animals were exposed to only three pH values for 7 days. The pH was manipulated by dissolving CO2 in the seawater to obtain two reduced pH treatments (pH −0.4 units and pH −0.7 units), which were compared with seawater at the natural pH level (8.1). Thereafter, the bivalves were concomitantly exposed to the three experimental pH values and environmentally relevant concentrations of diclofenac (0.00, 0.05 and 0.50 μg/L) for an additional 14 days. The activities of superoxide dismutase, catalase and cyclooxygenase, and lipid peroxidation and DNA strand-break formation were measured in both the gills and digestive gland after 7, 14 and 21 days of exposure to each experimental condition. The results show that the biochemical parameters measured in both the mussels and clams were more influenced by the reduced pH than by the contaminant or the pH*contaminant interaction, although the biomarker variation patterns differed depending on the species and tissues analysed. Generally, due to increases in its antioxidant defence, M. galloprovincialis was more resistant than R. philippinarum to both diclofenac exposure and reduced pH. Conversely, reduced pH induced a significant decrease in COX activity in both the gills and digestive gland of clams, possibly resulting in the increased DNA damage observed in the digestive gland tissue.

Continue reading ‘Does exposure to reduced pH and diclofenac induce oxidative stress in marine bivalves? A comparative study with the mussel Mytilus galloprovincialis and the clam Ruditapes philippinarum’

Seawater acidification aggravated cadmium toxicity in the oyster Crassostrea gigas: Metal bioaccumulation, subcellular distribution and multiple physiological responses

Highlights
• Ocean acidification aggravated the toxicity of environmental relevant concentration of Cd on C. gigas.
• OA exacerbated the oxidative stresses, histopathological damage, and apoptosis of Cd-exposed oysters.
• Apoptosis-pathway was generally stimulated in Cd-OA exposed oysters.
• Increased toxicity perhaps associated with the increased accumulation and altered subcellular distribution of Cd.

Abstract
Mounting evidence has demonstrated the combined effects of ocean acidification (OA) and other environmental stressors on marine organisms. Although metal pollution is widely distributed in coasts and estuaries, the combined effects of OA and metal pollution have received little attention until recent years. In this study, the accumulation and subcellular distribution of cadmium (Cd) and the physiological responses of the oyster Crassostrea gigas were investigated after 31 days of exposure to OA and Cd, either alone or in combination. Increased Cd accumulation was found both in gills (about 57% increase at pH 7.8, 22% increase at pH 7.6) and digestive glands (about 38% increase at pH 7.8, 22% increase at pH 7.6) of C. gigas under elevated pCO2 exposure. Although a similar total Cd accumulation pattern was seen in oyster gills and digestive glands, a higher partition of Cd in the BIM (biologically inactive metal) fractions of gills (about 60%) was found in Cd-exposed treatments compared to the digestive glands (about 45%), which might correspond to the generally lower toxicity in gills. Moreover, synergetic effects of Cd and OA on the oxidative stresses, histopathological damage, and apoptosis of exposed oysters were observed in this study, which might be explained by significant interactions of these two factors on increased generation of ROS. These findings demonstrated that OA could aggravate the toxicity of metals in marine organisms, with significant implications for coastal benthic ecosystems regarding the widespread metal contamination and the concurrent increase of acidified seawater.

Continue reading ‘Seawater acidification aggravated cadmium toxicity in the oyster Crassostrea gigas: Metal bioaccumulation, subcellular distribution and multiple physiological responses’

Synergistic effects of nano-ZnO and low pH of sea water on the physiological energetics of the thick shell mussel Mytilus coruscus

In order to investigate the ecotoxicological effects of nano-ZnO particles and seawater acidification on marine bivalves, the thick shell mussels, Mytilus coruscus were subjected to joint treatments with different nano-ZnO concentrations (0 [control], 2.5 and 10 mg L-1 [high]) under two pH levels (7.7 [low]and 8.1 [control]) for 14 days. The results showed that respiration rate (RR), absorption efficiency (AE), clearance rate (CR), O:N ratio and scope for growth (SFG) were significantly reduced with nano-ZnO concentration increase, but ammonium excretion rate (ER) was increased. Low pH significantly reduced CR, RR, SFG, and O:N ratio of the mussels especially under high nano-ZnO conditions, and significantly increased ER. Principal component analysis (PCA) showed consistent relationships among most tested parameters, especially among SFG, RR, O:N ratio and CR under the normal pH and 0 nano-ZnO conditions. Therefore, seawater acidification and nano-ZnO interactively impact the ecophysiological responses of mussels and cause more severe effects when they appear concurrently.

Continue reading ‘Synergistic effects of nano-ZnO and low pH of sea water on the physiological energetics of the thick shell mussel Mytilus coruscus’

Antidepressants in a changing ocean: Venlafaxine uptake and elimination in juvenile fish (Argyrosomus regius) exposed to warming and acidification conditions

Highlights

• VFX can be uptaken by fish through both water and diet.
• Both warming and acidification decreased VFX uptake in liver.
• VFX uptake in brain was favoured under warming conditions.
• VFX elimination in liver was impaired by warming and acidification.

Abstract

The presence of antidepressants, such as venlafaxine (VFX), in marine ecosystems is increasing, thus, potentially posing ecological and human health risks. The inherent mechanisms of VFX uptake and elimination still require further understanding, particularly accounting for the impact of climate change-related stressors, such as warming and acidification. Hence, the present work aimed to investigate, for the first time, the effects of increased seawater temperature (ΔT°C = +5 °C) and pCO2 levels (ΔpCO2 ∼1000 μatm, equivalent to ΔpH = −0.4 units) on the uptake and elimination of VFX in biological tissues (muscle, liver, brain) and plasma of juvenile meagre (Argyrosomus regius) exposed to VFX through two different exposure pathways (via water, i.e. [VFX ] ∼20 μg L−1, and via feed, i.e. [VFX] ∼160 μg kg−1 dry weight, dw). Overall, results showed that VFX can be uptaken by fish through both water and diet. Fish liver exhibited the highest VFX concentration (126.7 ± 86.5 μg kg−1 and 6786.4 ± 1176.7 μg kg−1 via feed and water exposures, respectively), as well as the highest tissue:plasma concentration ratio, followed in this order by brain and muscle, regardless of exposure route. Both warming and acidification decreased VFX uptake in liver, although VFX uptake in brain was favoured under warming conditions. Conversely, VFX elimination in liver was impaired by both stressors, particularly when acting simultaneously. The distinct patterns of VFX uptake and elimination observed in the different scenarios calls for a better understanding of the effects of exposure route and abiotic conditions on emerging contaminants’ toxicokinetics.

Continue reading ‘Antidepressants in a changing ocean: Venlafaxine uptake and elimination in juvenile fish (Argyrosomus regius) exposed to warming and acidification conditions’

Effects of water warming and acidification on bioconcentration, metabolization and depuration of pharmaceuticals and endocrine disrupting compounds in marine mussels (Mytilus galloprovincialis)

Highlights

• Citalopram showed the highest bioconcentration in mussels, methylparaben the lowest.
• Response to warming and acidification differed depending on the compound.
• Acidification decreased mussels capacity to metabolize venlafaxine.
• Acidification was the dominant factor when both stressors were combined.

Abstract

Warming and acidification are expected impacts of climate change to the marine environment. Besides, organisms that live in coastal areas, such as bivalves, can also be exposed to anthropogenic pollutants like pharmaceuticals (PhACs) and endocrine disrupting compounds (EDCs). In this study, the effects of warming and acidification on the bioconcentration, metabolization and depuration of five PhACs (sotalol, sulfamethoxazole, venlafaxine, carbamazepine and citalopram) and two EDCs (methylparaben and triclosan) were investigated in the mussel species (Mytilus galloprovincialis), under controlled conditions. Mussels were exposed to warming and acidification, as well as to the mixture of contaminants up to 15.7 μg L−1 during 20 days; followed by 20 days of depuration. All contaminants bioconcentrated in mussels with levels ranging from 1.8 μg kg−1 dry weight (dw) for methylparaben to 12889.4 μg kg−1 dw for citalopram. Warming increased the bioconcentration factor (BCF) of sulfamethoxazole and sotalol, whereas acidification increased the BCF of sulfamethoxazole, sotalol and methylparaben. In contrast, acidification decreased triclosan levels, while both stressors decreased venlafaxine and citalopram BCFs. Warming and acidification facilitated the elimination of some of the tested compounds (i.e. sotalol from 50% in control to 60% and 68% of elimination in acidification and warming respectively). However, acidification decreased mussels’ capacity to metabolize contaminants (i.e. venlafaxine). This work provides a first insight in the understanding of aquatic organisms’ response to emerging contaminants pollution under warming and acidification scenarios.

Continue reading ‘Effects of water warming and acidification on bioconcentration, metabolization and depuration of pharmaceuticals and endocrine disrupting compounds in marine mussels (Mytilus galloprovincialis)’


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Ocean acidification in the IPCC AR5 WG II

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