Climate change due to an increasing concentration of carbon dioxide in the atmosphere is a global issue. It can impact aquatic environments by affecting water flow, pollutant transformation and migration, and other toxicant-related effects. We assessed the interactive effects of temperature warming and pH changes on variations in accumulation of total arsenic (AsT) in the red alga Sarcodia suae at different levels of arsenite (AsIII). Result showed that AsT variations in the alga were moderated by significant joint effects of warming temperature and/or increasing pH levels and their interactions with increasing AsIII concentrations. Our study suggests possible deleterious impacts on macroalgal populations due to toxicological effects associated with prevailing environmental conditions. Therefore, improved pollution management, climate change adaptation, and mitigation strategies are needed to deal with current environmental issues and As aggravation.
Continue reading ‘Increasing arsenic accumulation as an implication of climate change: a case study using red algae’Posts Tagged 'toxicants'
Assessment of paracetamol toxic effects under varying seawater pH conditions on the marine polychaete Hediste diversicolor using biochemical endpoints
Published 13 April 2022 Science ClosedTags: annelids, biological response, BRcommunity, laboratory, multiple factors, North Atlantic, physiology, toxicants
Simple Summary
Context of climate change is being widely studied, nevertheless its effects in the toxicity of other contaminants have been poorly study. Particularly, the effects of ocean acidification on the modulation of pharmaceutical absorption and consequent effects, have not been extensively addressed before. In this study, we aimed to assess the effects of ocean acidification (specifically pH values of 8.2, 7.9, and 7.6) combined with paracetamol exposure (0, 30, 60, and 120 µg/L) on the polychaeta Hediste diversicolor. To do so, specific biomarkers were measured namely (CAT), glutathione S-transferases (GSTs), acetylcholinesterase (AChE), and cyclooxygenase (COX) activities, as well as thiobarbituric acid reactive substance (TBARS), were quantified to serve as ecotoxicological endpoints. Alterations of CAT, and GSTs activities, and TBARS levels indicate an alteration in redox balances. Differences in exposed pH levels indicate the possible modulation of the absorption of this pharmaceutical in ocean acidifications scenarios. Alterations in AChE were only observed following paracetamol exposure, not being altered by media pH. Hereby obtained results suggest that seawater acidification is detrimental to marine wildlife, since it may enhance toxic effects caused by environmental realistic concentrations of pharmaceuticals. This work is crucial to understand the potential effects of pharmaceuticals in a climate change scenario.
Abstract
Increasing atmospheric carbon dioxide (CO2) levels are likely to lower ocean pH values, after its dissolution in seawater. Additionally, pharmaceuticals drugs are environmental stressors due to their intrinsic properties and worldwide occurrence. It is thus of the utmost importance to assess the combined effects of pH decreases and pharmaceutical contamination, considering that their absorption (and effects) are likely to be strongly affected by changes in oceanic pH. To attain this goal, individuals of the marine polychaete Hediste diversicolor were exposed to distinct pH levels (8.2, 7.9, and 7.6) and environmentally relevant concentrations of the acidic drug paracetamol (PAR: 0, 30, 60, and 120 µg/L). Biomarkers such as catalase (CAT), glutathione S-transferases (GSTs), acetylcholinesterase (AChE), and cyclooxygenase (COX) activities, as well as peroxidative damage (through thiobarbituric acid reactive substance (TBARS) quantification), were quantified to serve as ecotoxicological endpoints. Data showed a general increase in CAT and a decrease in GST activities (with significant fluctuations according to the tested conditions of PAR and pH). These changes are likely to be associated with alterations of the redox cycle driven by PAR exposure. In addition, pH levels seemed to condition the toxicity caused by PAR, suggesting that the toxic effects of this drug were in some cases enhanced by more acidic conditions. An inhibition of AChE was observed in animals exposed to the highest concentration of PAR, regardless of the pH value. Moreover, no lipid peroxidation was observed in most individuals, although a significant increase in TBARS levels was observed for polychaetes exposed to the lowest pH. Finally, no alterations of COX activities were recorded on polychaetes exposed to PAR, regardless of the pH level. The obtained results suggest that seawater acidification is detrimental to marine wildlife, since it may enhance toxic effects caused by environmental realistic concentrations of acidic drugs, such as PAR. This work was crucial to evidence that ocean acidification, in the context of a global change scenario of increased levels of both atmospheric and oceanic CO2, is a key factor in understanding the putative enhanced toxicity of most pharmaceutical drugs that are of an acidic nature.
Continue reading ‘Assessment of paracetamol toxic effects under varying seawater pH conditions on the marine polychaete Hediste diversicolor using biochemical endpoints’Species specific responses to grazer cues and acidification in phytoplankton- winners and losers in a changing world
Published 11 April 2022 Science ClosedTags: biological response, BRcommunity, community composition, crustaceans, growth, laboratory, morphology, multiple factors, otherprocess, physiology, phytoplankton, toxicants, zooplankton
Phytoplankton induce defensive traits in response to chemical alarm signals from grazing zooplankton. However, these signals are potentially vulnerable to changes in pH and it is not yet known how predator recognition may be affected by ocean acidification. We exposed four species of diatoms and one toxic dinoflagellate to future pCO2 levels, projected by the turn of the century, in factorial combinations with predatory cues from copepods (copepodamides). We measured the change in growth, chain length, silica content, and toxin content. Effects of increased pCO2 were highly species specific. The induction of defensive traits was accompanied by a significant reduction in growth rate in three out of five species. The reduction averaged 39% and we interpret this as an allocation cost associated with defensive traits. Copepodamides induced significant chain length reduction in three of the four diatom species. Under elevated pCO2 Skeletonema marinoi reduced silica content by 30% and in Alexandrium minutum the toxin content was reduced by 30%. Using copepodamides to induce defensive traits in the absence of direct grazing provides a straightforward methodology to assess costs of defense in microplankton. We conclude that copepodamide signalling system is likely robust to ocean acidification. Moreover, the variable responses of different taxa to ocean acidification suggest that there will be winners and losers in a high pCO2 world, and that ocean acidification may have structuring effects on phytoplankton communities.
Continue reading ‘Species specific responses to grazer cues and acidification in phytoplankton- winners and losers in a changing world’Rising CO2 will increase toxicity of marine dinoflagellate Alexandrium minutum
Published 15 March 2022 Science ClosedTags: biological response, laboratory, morphology, multiple factors, phytoplankton, toxicants
Highlights
- High level CO2 significantly promoted growth of toxic Alexandrium minutum.
- Total yields of paralytic shellfish toxins by A. minutum were enhanced by rising CO2.
- Rising CO2 promoted transformation from GTX2&3 to more potent GTX1&4.
- High level CO2 may depress the release of PSTs from inside to outside of the cells.
- All the processes collectively increase the risk of A. minutum under CO2 enrichment.
Abstract
Ocean acidification caused by increasing emission of carbon dioxide (CO2) is expected to have profound impacts on marine ecological processes, including the formation and evolution of harmful algal blooms (HABs). We designed a set of experiments in the laboratory to examine the effects of increasing CO2 on the growth and toxicity of a toxic dinoflagellate Alexandrium minutum producing paralytic shellfish toxins (PSTs). It was found that high levels of CO2 (800 and 1,200 ppm) significantly promoted the growth of A. minutum compared to the group (400 ppm) representing the current CO2 level. The total yields of PSTs by A. minutum, including both intracellular and extracellular toxins, were significantly enhanced, probably due to the induction of core enzyme activity and key amino acids synthesis for PST production. More interestingly, high level of CO2 promoted the transformation from gonyautoxin2&3 to gonyautoxin1&4 and depressed the release of PSTs from inside to outside of the cells. All these processes collectively led to an apparent increase of A. minutum toxicity. Our study demonstrated that rising CO2 would increase the risk of toxic A. minutum based on the comprehensive analyses of different processes including algal growth and toxin synthesis, transformation and release.
Continue reading ‘Rising CO2 will increase toxicity of marine dinoflagellate Alexandrium minutum’Ocean acidification, but not environmental contaminants, affects fertilization success and sperm motility in the sea urchin Paracentrotus lividus
Published 1 March 2022 Science ClosedTags: biological response, echinoderms, laboratory, Mediterranean, multiple factors, performance, reproduction, toxicants
Ocean acidification poses an increasing concern for broadcast spawning species that release gametes in the water column where fertilization occurs. Indeed, the functionality of gametes and their interactions may be negatively affected by reduced pH. Susceptibility to other environmental stressors, such as pollutants, may be also altered under acidified conditions, resulting in more detrimental effects. To verify this hypothesis, combined exposures to CO2-driven acidification and environmentally relevant concentrations (0.5 µg/L) of three contaminants (caffeine, diclofenac, and PFOS, all singularly or in mixture) were carried out to highlight potential negative effects on fertilization success and motility of sperm in the sea urchin Paracentrotus lividus. Our results showed a significant reduction in the percentage of fertilized eggs when sperm were pre-exposed to reduced pH (ambient pH minus 0.4 units) compared to that of controls (ambient, pH = 8.1). Sperm speed and motility also decreased when sperm were activated and then exposed at reduced pH. Conversely, at both pH values tested, no significant effect due to the contaminants, nor of their interaction with pH, was found on any of the biological endpoints considered.
Continue reading ‘Ocean acidification, but not environmental contaminants, affects fertilization success and sperm motility in the sea urchin Paracentrotus lividus’Methane hydrate dissociation across the Oligocene–Miocene boundary
Published 28 February 2022 Science ClosedTags: Antarctic, field, modeling, paleo, regionalmodeling, sediment, toxicants
Methane hydrate dissociation has long been considered as a mechanism for global carbon cycle perturbations, climate change and even mass extinctions in Earth’s history. However, direct evidence of hydrate destabilization and methane release coinciding with such events is scarce. Here we report the presence of diagnostic lipid biomarkers with depleted carbon isotopes from three sites in the Southern Ocean that are directly linked to methane release and subsequent oxidation across the Oligocene–Miocene boundary (23 million years ago). The biomarker evidence indicates that the hydrate destabilization was initiated during the peak of the Oligocene–Miocene boundary glaciation and sea-level low stand, consistent with our model results suggesting the decrease in hydrostatic pressure eroded the base of global methane hydrate stability zones. Aerobic oxidation of methane in seawater consumes oxygen and acidifies the ocean, acting as a negative feedback that perhaps facilitated the rapid and mysterious termination of glaciation in the early Miocene.
Continue reading ‘Methane hydrate dissociation across the Oligocene–Miocene boundary’Responses of Ruditapes philippinarum to contamination by pharmaceutical drugs under ocean acidification scenario
Published 17 February 2022 Science ClosedTags: biological response, mollusks, multiple factors, North Atlantic, physiology, toxicants
Highlights
- Ocean acidification alters the impacts of pharmaceutical drugs in marine bivalves.
- Regardless the pH, drug combination had fewer impacts than drugs acting alone.
- At control pH, CTZ acting alone caused the highest impacts.
- Reduced pH per se caused cellular damage.
- At reduced pH, CBZ and CTZ, alone or combined had limited impacts.
Abstract
In coastal systems, organisms are exposed to a multitude of stressors whose interactions and effects are poorly studied. Pharmaceutical drugs and Climate Change consequences, such as reduced pH, are examples of stressors affecting marine organisms, as bivalves. Although a vast literature is available for the effects of these stressors when acting individually, very limited information exists on the impacts that the combination of both can have on marine bivalves. For this reason, this study aimed to evaluate the impacts of a simulated ocean acidification scenario (control pH, 8.0; reduced pH, pH 7.6) on the effects of the antiepileptic carbamazepine (CBZ, 1 μg/L) and the antihistamine cetirizine (CTZ, 0.6 μg/L), when acting individually and combined (CBZ + CTZ), on the edible clam Ruditapes philippinarum. After 28 days of exposure, drug concentrations, bioconcentration factors and biochemical parameters related to the clam’s metabolic capacity and oxidative stress were evaluated. The results showed that R. philippinarum clams responded differently to pharmaceutical drugs depending on the pH tested, influencing both bioconcentration and biological responses. In general, drug combined treatments showed fewer impacts than drugs acting alone, and acidification seemed to activate at a higher extension the elimination processes that were not activated under control pH. Also, reduced pH per se exerted negative impacts (e.g., cellular damage) on R. philippinarum and the combination with pharmaceutical drugs did not enhance the toxicity.
Continue reading ‘Responses of Ruditapes philippinarum to contamination by pharmaceutical drugs under ocean acidification scenario’Moderate acidification mitigates the toxic effects of phenanthrene on the mitten crab Eriocheir sinensis
Published 11 February 2022 Science ClosedTags: biological response, crustaceans, laboratory, mitigation, molecular biology, mortality, multiple factors, North Pacific, physiology, toxicants
Highlights
- Phenanthrene at environmentally-relevant concentration caused toxic effects on crabs.
- Acidification (pH6.5) mitigated the toxic effects of phenanthrene on crabs.
- Phenanthrene caused enrichment of disease and immune related pathways.
- The interaction of pH 6.5 and phenanthrene made the metabolic pathway more enriched.
Abstract
Freshwater acidification and phenanthrene may result in complex adverse effects on aquatic animals. Juvenile Chinese mitten crabs (Eriocheir sinensis) were exposed to different pH levels (7.8, 6.5, and 5.5) under phenanthrene (PHE) (0 (control) and 50 μg/L) conditions for 14 days. Antioxidant and transcriptomic responses were determined under stress conditions to evaluate the physiological adaptation of crabs. Under the control pH 7.8, PHE led to significantly reduced activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione S-transferase (GST), but increased glutathione peroxidase (GSH-Px), 7-ethoxyresorufin-o-deethylase (EROD) activities, and malondialdehyde (MDA) levels. However, moderate acidification (pH 6.5) changed PHE effects by increasing antioxidant enzymes. Acidification generally reduced SOD, GPx, GST and EROD activities, but increased CAT, GR, MDA. Compared with pH7.8 group, pH7.8 × PHE and pH6.5 × PHE groups had 1148 and 1498 differentially expressed genes, respectively, with “Biological process” being the main category in the two experimental groups. pH7.8 × PHE treatment caused significant enrichment of disease and immune-related pathways, while under pH6.5 × PHE, more pathways related to metabolism, detoxification, environmental information processing, and energy supply were significantly enriched. Thus, PHE had a significant inhibitory effect on antioxidant performance in crabs, while moderate acidification (pH6.5) mitigated the toxic effects of PHE. Overall, moderate acidification has a positive effect on the defense against the negative effects of PHE in Chinese mitten crabs, and this study provides insights into the defense mechanism of crustaceans in response to combined stress of acidification and PHE.
Continue reading ‘Moderate acidification mitigates the toxic effects of phenanthrene on the mitten crab Eriocheir sinensis’Does pH variation influence the toxicity of organic contaminants in estuarine sediments? Effects of Irgarol on nematode assemblages
Published 2 February 2022 Science ClosedTags: biological response, community composition, laboratory, multiple factors, nematodes, otherprocess, physiology, sediment, South Atlantic, toxicants
Highlights
- Effects of acidification on the Irgarol toxicity to a benthic community was assessed.
- Lower nematode diversity was observed at the highest Irgarol concentration.
- Estuarine nematode assemblage was impacted by continuous exposure to low pHs.
- Toxicity of Irgarol was independent of pH variation.
Abstract
Natural pH values in coastal waters vary largely among locations, ecosystems, and time periods; still, there is an ongoing acidification trend. In this scenario, more acidic pH values can alter bioavailability of organic contaminants, to organisms. Despite this, interactive effects between pH and chemical substances are not usually considered in Ecological Risk Assessment protocols. This study investigated the effects of pH on the toxicity of a hydrophobic organic compound on a benthic community using a microcosm experiment setup to assess the response of nematode assemblages exposed to environmentally relevant concentrations of Irgarol at two natural pH conditions. Estuarine nematode assemblages were exposed to two concentrations of Irgarol at pH 7.0 and 8.0 for periods of 7 and 35 days. Lower diversity of nematode genera was observed at the highest tested Irgarol concentration (1281 ± 65 ng.g−1). The results showed that the effects of Irgarol contamination were independent of pH variation, indicating no influence of acidification within this range on the toxicity of Irgarol to benthic meiofauna. However, the results showed that estuarine nematode assemblages are impacted by long-term exposure to low (but naturally occurring) pHs. This indicates that estuarine organisms may be under naturally high physiological pressure and that permanent changes in the ecosystem’s environmental factors, such as future coastal ocean acidification, may drive organisms closer to the edges of their tolerance windows.
Continue reading ‘Does pH variation influence the toxicity of organic contaminants in estuarine sediments? Effects of Irgarol on nematode assemblages’
Effects of water acidification on immune responses of the gercacinid,
Cardiosoma armatum (Herklots, 1851)
Published 18 January 2022
Science
Closed
Tags: biological response, crustaceans, laboratory, North Atlantic, physiology, toxicants
The biological response to chemical pollutants reflects the acid–base status of an aquatic ecosystem. The gercacinid, Cardiosoma armatum (75±0.1 g) was exposed to acidified waters to evaluate the effects on its immune parameters. The crabs were exposed to pH 4.0, 5.0, 6.0 and 7.8 (control) for 28 days. The hematological parameters of control crabs and crabs exposed to varied doses of acidified water indicated a marked reduction. Significant (p<0.05) higher alkaline phosphatase and albumen were obtained in pH 4.0, 5.0 and 6.0 compared to control; other values were mostly similar to control. The highest superoxide dismutase (SOD) (252.61±0.06 min/mg pro) was recorded in control group, while highest CAT activity (2.08±0.16 min/mg protein) was recorded in crabs exposed to pH 4 treatment. Furthermore, the control group’s SOD activity was significantly higher than the exposed groups. With a lower pH, the quantities of malondialdehyde increased substantially and were significantly different from the control group. While these findings demonstrate that changes in pH have limited impact on energy use, decreasing immune system conditions show that C. armatum is susceptible to pH variations and may be influenced in aquaculture, where a pH drop is more prominent.
Continue reading ‘Effects of water acidification on immune responses of the gercacinid,Cardiosoma armatum (Herklots, 1851)’
Under pressure: nanoplastics as a further stressor for sub-Antarctic pteropods already tackling ocean acidification
Published 4 January 2022 Science ClosedTags: Antarctic, biological response, laboratory, mollusks, mortality, multiple factors, toxicants, zooplankton
In the Southern Ocean (SO), plastic debris has already been found in waters and sediments. Nanoplastics (<1 μm) are expected to be as pervasive as their larger counterparts, but more harmful to biological systems, being able to enter cells and provoke toxicity. In the SO, (nano)plastic pollution occurs concomitantly with other environmental threats such as ocean acidification (OA), but the potential cumulative impact of these two challenges on SO marine ecosystems is still overlooked. Here the single and combined effects of nanoplastics and OA on the sub-Antarctic pteropod Limacina retroversa are investigated under laboratory conditions, using two surface charged polystyrene nanoparticles (PS NPs) as a proxy for nanoplastics. Sub-Antarctic pteropods are threatened by OA due to the sensitivity of their shells to changes in seawater carbonate chemistry. Short-term exposure (48 h) to PS NPs compromised the ability of pteropods to counteract OA stress, resulting in a negative effect on their survival. Our results highlights the importance of addressing plastic pollution in the context of climate change to identify realistic critical thresholds of SO pteropods.
Continue reading ‘Under pressure: nanoplastics as a further stressor for sub-Antarctic pteropods already tackling ocean acidification’Responses of biogenic sulfur compounds concentrations to dust aerosol enrichment and ocean acidification in the western Pacific Ocean
Published 20 December 2021 Science ClosedTags: biological response, laboratory, morphology, multiple factors, North Pacific, phytoplankton, toxicants
Abstract
Deck incubation experiments were conducted to investigate how the addition of atmospheric dust aerosols and ocean acidification (OA) affect phytoplankton growth and the production of dimethylsulfide (DMS), its precursor dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO) in the oligotrophic western Pacific Ocean. The incubation experiment showed that the deposition of simulated dust aerosols greatly influenced phytoplankton growth and the release of biogenic sulfur compounds (BSCs). Furthermore, it altered the N:P ratios in seawater and phytoplankton community composition, elevating the proportions of strong DMSP and DMSO producers (mainly haptophytes). The average Chl-a and DMS/P/O concentrations in the acidified treatment (pH 7.9) were 86.76%, 82.53%, 84.17%, and 231.06% higher, respectively, than in the control. The results indicated that lower pH promoted the growth of diatoms and, to a certain extent, the release of the three BSCs.
Plain Language Summary
About 500 Mt of dust are deposited in the ocean each year. Atmospheric dust deposition can supply enough nutrients to the ocean to enhance marine primary productivity and affect the subsequent concentrations of the climate-gas dimethylsulfide (DMS) and related biogenic sulfur compounds (BSCs). Besides, ocean acidification is increasingly severe and low pH can affect the growth of phytoplankton. Therefore, we carried out deck incubation experiments to determine how the deposition of atmospheric dust aerosols and ocean acidification (OA) alter the production of BSCs. We found that the addition of dust aerosols elevated the abundance of strong DMSP and DMSO producers (Phaeocystis sp. and Gephyrocapsa oceanica) and increased the concentrations of sulfur compounds. The lower pH accelerated the growth of diatoms in the early and mid-late stages of treatments and promoted the production of BSCs.
Continue reading ‘Responses of biogenic sulfur compounds concentrations to dust aerosol enrichment and ocean acidification in the western Pacific Ocean’Combined effects of short term exposure to seawater acidification and microplastics on the early development of the oyster Crassostrea rivularis
Published 1 December 2021 Science ClosedTags: biological response, laboratory, mollusks, multiple factors, physiology, reproduction, toxicants
Highlights
- OA and MPs increased the deformation rate of C. rivularis spawn.
- OA and MPs impaired the shell development of the C. rivularis larvae.
- The moderate concentration of MPs exposure induced the increase of ALP.
- The oyster larva has filter selectivity to reduce the microplastics intake.
Abstract
Ocean acidification and microplastics pollution are two consequences of anthropogenic activities. In regions such as estuarine areas, ocean acidification (OA) and microplastics (MPs) pollution are occurring simultaneously. The present study tested the combined effects of OA and MPs on the embryonic development and physiological response of the larval oyster Crassostrea rivularis in a short exposure duration. The fertilization process was exposed to six combinations of three MPs levels (0, 10 and 1000 items L−1) × two pH levels (7.3, 8.1) for 9 d after hatching. As a result, the hatching rate was not affected by either pH reduction or MPs exposure, while the deformation rate increased under low pH, MPs exposure and their combination. Larval shell length was reduced under low pH, MPs exposure and the combined exposure of the two factors. Furthermore, swimming speed decreased under low pH throughout the experiment but the MPs‘ effect was limited. Predictably, MPs in the body increased with the increase of MPs concentration. Compared to low pH, the oyster ingested more MPs under normal pH. But combined OA and MPs didn’t affect the MPs intake. Moreover, no significant effects of OA and MPs on total antioxidant capacity and malondialdehyde were observed. However, alkaline phosphatase was significantly affected by low pH and MPs exposure independently. PCA showed that development of C. rivularis larvae changed over time and MPs concentration increase augmented intake of MPs by oysters. Consequently, we speculate that OA and MPs exposure may harm oyster C. rivularis embryonic and larval development, but not induce their antioxidant response in a short duration. Long term study about combined effects of OA and MPs on C. rivularis development is needed in the future.
Continue reading ‘Combined effects of short term exposure to seawater acidification and microplastics on the early development of the oyster Crassostrea rivularis’
