metals Archives - Ocean Acidification

Posts Tagged 'metals'

DNA methylation plasticity drives copepod resilience to coastal high pCO2 and cadmium pollution under multigenerational exposure

Published 20 October 2025 Science Closed
Tags: adaptation, biological response, crustaceans, laboratory, metals, molecular biology, mortality, multiple factors, North Pacific, otherprocess, reproduction, zooplankton

Highlights

Fluctuating acidification caused the most Cd multigenerational toxicity in copepods.
The adverse effects of acidification and Cd tended to intensify during F1-F3.
The copepods potentially adapted to combined exposure in F4.
DNA hypomethylation rendered copepods presenting the adaptive potential.

ABSTRACT

The vast majority of coastal organisms have been facing multigenerational scenarios of fluctuatingly high pCO₂ and Cd pollution in their natural habitats. However, the adaptive capacity of these organisms to such combined stressors and the underlying mechanisms remain poorly understood. In this study, we conducted a multigenerational experiment (F1-F4) to investigate the adaptive responses of the marine copepod Tigriopus japonicus to combined fluctuatingly high pCO₂ and Cd exposure, along with the associated mechanisms. Our findings revealed that steady high pCO₂ aggravated Cd multigenerational toxicity, and it was more under fluctuating acidification. Notably, by the F4 generation, copepods potentially adapted to the combined stressors. Through transcriptomic and DNA methylation analyses of copepods from the F1 and F4 generations, we found that under combined exposure, F1 copepods likely reallocated more energy to counteract Cd toxicity; however, DNA hypermethylation inhibited Cd exclusion and detoxification/stress response pathways, ultimately compromising development and reproduction. In contrast, in the F4 generation, DNA hypomethylation enhanced processes such as cuticle repair program, compensatory mechanism (e.g., detoxification and immune response), and reproduction, consequently increasing the copepod’s fitness. These findings reveal an epigenetic basis for phenotypic acclimatization, offering marine copepods a supplementary mechanism to cope with combined stressors.

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Synergistic effects of ocean acidification and copper on gamete health and fertilization potential of the Pacific oyster Magallana (Crassostrea) gigas

Published 26 August 2025 Science Closed
Tags: adaptation, biological response, laboratory, metals, mollusks, mortality, multiple factors, North Pacific, otherprocess, physiology, reproduction

Highlights

Ocean acidification exacerbates copper toxicity in Pacific oyster gametes.
Sperm show higher sensitivity to combined stressors than oocytes.
Fertilization success decreases at low pH and high copper concentrations.

Abstract

Ocean acidification (OA) and metal pollution pose significant threats to marine ecosystems, particularly in coastal areas. This study investigated the synergistic effects of OA and copper toxicity on Pacific oyster (Magallana gigas) gametes. Spermatozoa and oocytes were exposed to varying pCO₂ levels and copper concentrations for 2 h. Flow cytometry was used to assess cell mortality, reactive oxygen species (ROS) production, and fertilization success. Results showed increased mortality in both sperm and oocytes with rising copper and pCO₂ levels, with sperm exhibiting higher sensitivity. ROS production in gametes displayed complex patterns, suggesting adaptive responses at lower copper concentrations and potential cell death at higher levels. Fertilization success decreased significantly at lower pH combined with higher copper concentrations (> 10 μg Cu/L). These findings demonstrate that OA exacerbates copper toxicity in M. gigas gametes through interactive effects, highlighting the need to consider multiple stressors when assessing pollutant impacts on coastal ecosystems.

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Influence of CO2-induced acidification and temperature increased on the toxicity of metals in sediment in the mussel Mytella charruana

Published 15 April 2025 Science Closed
Tags: biological response, laboratory, metals, mollusks, multiple factors, physiology, South Pacific, temperature

Environmental and climate changes have placed increasing pressure on the resilience of marine ecosystems. In addition to these transformations, coastal environments are also affected by anthropogenic stressors, such as metal contamination. Bivalves play a crucial ecological role in marine and estuarine ecosystems. This study aimed to evaluate the effects of CO₂-induced acidification, warming, and mixed metals contamination on the mangrove mussel Mytella charruana. We evaluated DNA damage (strand breaks), lipid peroxidation (LPO) levels, and reduced glutathione (GSH) content, as well as the enzymatic activities of glutathione S-transferase (GST) and glutathione peroxidase (GPx) in the gills and digestive glands. Additionally, neurotoxicity was assessed in muscle tissues through acetylcholinesterase (AChE) activity. Laboratory experiments were conducted using sediments spiked with metals (Cu, Pb, Zn, and Hg), alongside a control group (non-spiked sediments), combining with three pH levels (7.5, 7.1, and 6.7) and two temperatures (25 and 27°C). Five mussels per treatment (four replicates) were exposed for 96 h. Two pools of two organisms each were separated per replicate (n = 8) and their gills, digestive glands, and muscles were dissected for biochemical biomarkers analyses. Temperature increase and metal contamination were the primary factors modulating antioxidant responses in the gills and digestive glands, as well as AChE activity in the muscle. However, when combined with CO₂-induced acidification, these stressors also affected DNA integrity and LPO. Acidification alone showed no effect for any biomarker analyzed. Higher IBR values indicated effects for combined metal exposure, even at concentrations below individual safety levels. Here, we provide insights from a short-term experiment on the complex interactions between predicted scenarios, in which climate change stressors influenced estuarine mussel responses when associated with a mixture of metals in sediments. These findings contribute to understanding of organismal responses in complex scenarios of contamination and climate change, particularly in estuarine environments.

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Combined effects of ocean acidification and copper exposure on the polyps of moon jellyfish Aurelia coerulea

Published 24 March 2025 Science Closed
Tags: biological response, cnidaria, laboratory, metals, morphology, multiple factors, performance, physiology, reproduction, respiration

Ocean acidification (OA) can interact with Copper (Cu) pollutants and threaten marine organisms and ecosystems. In this study, we assessed the effects of OA and Cu²⁺, alone and in combination, on the polyps of Aurelia coerulea, a common jellyfish renowned for its complex life cycle and frequent global blooms. The results revealed that ocean acidification and Cu²⁺ exposure significantly inhibited the activities of catalase, Ca²⁺-ATPase, acid phosphatase, and alkaline phosphatase in polyps, resulting in antioxidative stress effects and a significant increase in respiratory metabolism. In addition, the combination of ocean acidification and Cu²⁺ exposure caused severe tissue damage to polyps, thereby impeding their predation behavior and reducing their asexual reproduction rates. These two environmental stressors showed synergistic effects on the Ca²⁺-ATPase activity, predation rate, reproduction rate, and injury index of polyps. Therefore, reduced seawater pH and copper contamination adversely affect the physiology, growth, and development of A. coerulea polyps, which may affect the survival and population dynamics of wild populations.

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Response of the photosynthetic physiology of Ulva lactuca to Cu toxicity under ocean acidification

Published 8 January 2025 Science Closed
Tags: algae, biological response, growth, laboratory, metals, multiple factors, photosynthesis, physiology

Highlights

Low Cu concentrations promote the growth of Ulva lactuca.
The growth of Ulva lactuca was decreased with Cu increase under low CO₂ condition.
Ocean acidification can exacerbate the adverse effects of Cu on Ulva lactuca.

Abstract

Ocean acidification can significantly affect the physiological performance of macroalgae. While copper (Cu) is an essential element for macroalgae and has been extensively studied, the interactive effects of ocean acidification and Cu on these organisms remain less understood. In this study, we measured the photosynthetic characteristics of Ulva lactuca exposed to varying Cu concentrations at two CO₂ levels (415 ppmv, low concentration; 1000 ppmv, high concentration). The results indicated that during chronic toxicity testing, the growth of juvenile U. lactuca significantly increased at Cu concentrations of 0.001 μM, 0.01 μM, and 0.1 μM regardless of low CO₂ concentrations or high CO₂ concentrations condition. In acute toxicity tests, elevated Cu concentrations negatively impacted the growth rate, yield, and photosynthetic rate of U. lactuca under low CO₂ concentrations. Conversely, high CO₂ concentrations enhanced the photosynthetic capacity of U. lactuca with increased Cu concentrations, while the growth rate significantly decreased at Cu concentration of 1.5 μM. Additionally, the activities of peroxidase (POD) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) increased, with an enhancement of malondialdehyde (MDA) content at 1.5 μM Cu under high CO₂ conditions. However, the structure of the chloroplast thylakoid was disrupted by elevated Cu concentrations. These findings suggest that low Cu concentrations promote the growth of U. lactuca, whereas high Cu concentrations inhibit algal growth, and ocean acidification may exacerbate the adverse effects of Cu on U. lactuca in acute toxicity tests.

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Cellular and genetic responses of Phaeodactylum tricornutum to seawater acidification and copper exposure

Published 2 January 2025 Science Closed
Tags: biological response, laboratory, metals, molecular biology, morphology, multiple factors, North Pacific, physiology, phytoplankton, toxicants

Highlights

Seawater acidification reduced Cu uptake in marine diatom Phaeodactylum tricornutum.
Seawater acidification resulted in rougher surfaces, lower adhesion and modulus in the diatom.
Diatoms regulated Cu homeostasis via FRE1, CTR1, and ATPase 5-1B transporters.
The expression of CTR1 and FRE1 were significantly downregulated in response to seawater acidification.

Abstract

The ongoing decline in seawater pH, driven by the absorption of excess atmospheric CO₂, represents a major environmental issue. This reduction in pH can interact with metal pollution, resulting in complex effects on marine phytoplankton. In this study, we examined the combined impacts of seawater acidification and copper (Cu) exposure on the marine diatom Phaeodactylum tricornutum. Our data indicate that elevated pCO₂ had a minor effect on the growth and photochemistry and overall performance of P. tricornutum. However, seawater acidification significantly influenced cell size, surface roughness, and adhesion. Higher pCO₂ levels led to increased Cu accumulation in P. tricornutum under low ambient Cu concentrations, while significantly reducing Cu accumulation. The smaller cell size and reduced negative charge on the cell surface may explain the decreased Cu accumulation and toxicity. In response to metal stress, P. tricornutum upregulated Cu efflux to mitigate the increased Cu stress in acidified seawater. The expression of the metal transporter gene CTR1 and the reductase gene FRE1 were significantly downregulated, while ATPase5-1B was upregulated in cells exposed to elevated Cu concentrations at 1200 μatm pCO₂. Our study provides useful insights into the interactions between metals and diatoms in an increasingly acidified ocean.

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Multigenerational impact of global change: increased mercury toxicity in a marine copepod

Published 26 November 2024 Science Closed
Tags: biological response, BRcommunity, crustaceans, laboratory, metals, molecular biology, multiple factors, physiology, reproduction, toxicants, zooplankton

Highlights

OA plus OW significantly increased MeHg accumulation in Hg-treated T. japonicus.
Hg-induced reproductive toxicity was more serious under OA plus OW.
Transcriptomic analysis supported higher Hg toxicity in copepods under OA plus OW.
Accurate Hg toxicity assessment should consider global change stressors.

Abstract

A multi-generational experiment (F1-F4) was conducted for a marine copepod Tigriopus japonicus to investigate its physiological and molecular responses to mercury (Hg) pollution and/or its combination with ocean acidification (OA) plus ocean warming (OW). The projected future scenario, i.e., OA plus OW (AW) significantly increased methylmercury accumulation in copepods by 1.14 times, despite insignificant change for total Hg bioaccumulation. Transcriptomic analysis indicated that copepods initiated several detoxification defense processes, including reactive oxygen species metabolic process, glutathione metabolism, and protein refolding, in response to increased Hg toxicity under combined exposure of AW and Hg; meanwhile, inhibited energy metabolism was observed in this case, linking to reduced number of nauplii/clutch but accelerated development in copepods probably due to an energetic trade-off. Increased Hg toxicity due to AW could also be ascribed to the impairment in immune defense (e.g., lysosome and vitamin metabolism) and reproduction-related processes (e.g., growth factor activity). Collectively, this study reveals the multi-generational response mechanism of copepods to Hg pollution under global change, emphasizing an exacerbated adverse effect of Hg, and it provides a scientific basis for an accurate understanding of the potential impact of Hg pollution on marine ecosystems.

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Variations of polyphenols and carbohydrates of Emiliania huxleyi grown under simulated ocean acidification conditions

Published 30 October 2024 Science Closed
Tags: biological response, laboratory, metals, multiple factors, photosynthesis, physiology, phytoplankton

Cultures of the coccolithophore Emiliania huxleyi were grown under four different CO₂-controlled pH conditions (7.75, 7.90, 8.10, and 8.25) to explore variations in extra- and intracellular polyphenols and carbohydrates in response to different ocean acidification scenarios. Acidification did not significantly affect final cell densities and carbohydrate contents. Intra- and extracellular phenolic compounds were identified and quantified by reverse-phase high-performance liquid chromatography (RP-HPLC), with the highest concentrations of total exuded phenolics at a pH of 8.25 (43 ± 3 nM) and 7.75 (18.0 ± 0.9 nM). Accumulation of intracellular phenolic compounds was observed in cells with decreasing pH, reaching the maximum level (9.24 ± 0.19 attomole per cell) at the lowest pH (7.75). The phenolic profiles presented significant changes in exuded epicatechin and protocatechuic acid (p < 0.05 and 0.01, respectively) and intracellular vanillic acid (p < 0.001), which play an essential role in the availability of trace metals. A significant increase in chlorophyll a content was observed in cells grown at the most acidic pH (p < 0.01), which also showed significantly higher radical inhibition activity (p < 0.01). The nature and concentration of these organic compounds present in the culture medium may influence trace metal bioavailability, affecting the biogeochemical cycling of carbon and microbial functional diversity.

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Effect of copper and temperature on the photosynthetic physiological characteristics of Ulva linza under elevated CO2 concentrations

Published 18 September 2024 Science Closed
Tags: algae, biological response, laboratory, metals, mitigation, morphology, multiple factors, North Pacific, physiology, temperature, toxicants

Highlights

The growth of Ulva linza was reduced with increased CO₂ and Cu at 5 °C.
Elevated CO₂ alleviated toxic effects on thalli at high Cu concentrations at 15 °C.
The response of algal to Cu pollution, high CO₂, and temperature was analyzed.

Abstract

Copper (Cu) is vital for macroalgae’s functions, but high concentrations can be toxic. Rising CO₂ levels affect algal growth and Cu bioavailability. In this study, the results reveal that at 5 °C, low Cu increased Ulva linza growth, while high Cu and elevated CO₂ decreased growth. At 10 °C, low Cu and elevated CO₂ enhanced growth, but high Cu did not have a significant impact. At 15 °C, high Cu reduced growth, but elevated CO₂ offset this effect. Furthermore, under elevated CO₂ conditions, the chloroplast structure of the algae appeared to be denser, accompanied by a large amount of starch granules, compared to low CO₂ conditions. These results emphasize that lower temperatures, in conjunction with elevated CO₂ concentration, could intensify the toxic effects of high Cu concentrations on thalli. However, at higher temperatures, elevated CO₂ concentration appeared to be capable of mitigating the detrimental effects of heavy metals on algae.

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Magnesium (Mg/Ca, δ26Mg), boron (B/Ca, δ11B), and calcium ([Ca2+]) geochemistry of Arctica islandica and Crassostrea virginica extrapallial fluid and shell under ocean acidification

Published 9 September 2024 Science Closed
Tags: biological response, BRcommunity, calcification, laboratory, metals, mollusks, multiple factors, physiology

The geochemistry of biogenic carbonates has long been used as proxies to record changing seawater parameters. However, the effect of ocean acidification on seawater chemistry and organism physiology could impact isotopic signatures and how elements are incorporated into the shell. In this study, we investigated the geochemistry of three reservoirs important for biomineralization – seawater, the extrapallial fluid (EPF), and the shell – in two bivalve species, Crassostrea virginica and Arctica islandica. Additionally, we examined the effects of three ocean acidification conditions (ambient: 500 ppm CO₂, moderate: 900 ppm CO₂, and high: 2800 ppm CO₂) on the geochemistry of the same three reservoirs for C. virginica. We present data on calcification rates, EPF pH, measured elemental ratios (Mg/Ca, B/Ca), and isotopic signatures (δ²⁶Mg, δ¹¹B). In both species, comparisons of seawater and EPF Mg/Ca and B/Ca, [Ca²⁺], and δ²⁶Mg indicate that the EPF has a distinct composition that differs from seawater. Shell δ¹¹B did not faithfully record seawater pH and δ¹¹B-calculated pH values were consistently higher than pH measurements of the EPF with microelectrodes, indicating that the shell δ¹¹B may reflect a localized environment within the entire EPF reservoir. In C. virginica, EPF Mg/Ca and B/Ca, as well as absolute concentrations of Mg, B, and [Ca²⁺], were all significantly affected by ocean acidification, indicating that OA affects the physiological pathways regulating or storing these ions, an observation that complicates their use as proxies. Reduction in EPF [Ca²⁺] may represent an additional mechanism underlying reduction in calcification in C. virginica in response to seawater acidification. The complexity of dynamics of EPF chemistry suggest boron proxies in these two mollusc species are not straightforwardly related to seawater pH, but ocean acidification does lead to both a decrease in microelectrode pH and boron-isotope-based pH, potentially showing applicability of boron isotopes in recording physiological changes. Collectively, our findings show that bivalves have high physiological control over the internal calcifying fluid, which presents a challenge to using boron isotopes for reconstructing seawater pH.

Continue reading ‘Magnesium (Mg/Ca, δ26Mg), boron (B/Ca, δ11B), and calcium ([Ca2+]) geochemistry of Arctica islandica and Crassostrea virginica extrapallial fluid and shell under ocean acidification’

Ocean acidification alleviated nickel toxicity to a marine copepod under multigenerational scenarios but at a cost with a loss of transcriptome plasticity during recovery

Published 31 May 2024 Science Closed
Tags: biological response, chemistry, laboratory, metals, molecular biology, mollusks, multiple factors, North Pacific, physiology

Highlights

Ni multigenerational exposure significantly decreased the fitness of T. japonicus.
OA markedly alleviated Ni multigenerational toxicity in T. japonicus.
Antagonism was observed for OA and Ni at transcriptomic and physiological levels.
Parental co-exposure to OA and Ni reduced the transcriptome plasticity in recovery.

Abstract

Marine ecosystem has been experiencing multiple stressors caused by anthropogenic activities, including ocean acidification (OA) and nickel (Ni) pollution. Here, we examined the individual/combined effects of OA (pCO₂ 1000 μatm) and Ni (6 μg/L) exposure on a marine copepod Tigriopus japonicus for six generations (F1-F6), followed by one-generation recovery (F7) in clean seawater. Ni accumulation and several important phenotypic traits were measured in each generation. To explore within-generation response and transgenerational plasticity, we analyzed the transcriptome profile for the copepods of F6 and F7. The results showed that Ni exposure compromised the development, reproduction and survival of copepods during F1-F6, but its toxicity effects were alleviated by OA. Thus, under OA and Ni combined exposure, due to their antagonistic interaction, the disruption of Ca²⁺ homeostasis, and the inhibition of calcium signaling pathway and oxytocin signaling pathway were not found. However, as a cost of acclimatization/adaption potential to long-term OA and Ni combined exposure, there was a loss of transcriptome plasticity during recovery, which limited the resilience of copepods to previously begin environments. Overall, our work fosters a comprehensive understanding of within- and transgenerational effects of climatic stressor and metal pollution on marine biota.

Continue reading ‘Ocean acidification alleviated nickel toxicity to a marine copepod under multigenerational scenarios but at a cost with a loss of transcriptome plasticity during recovery’

The incorporation of strontium and barium into the otoliths of the flounder Paralichthys olivaceus at early life stages demonstrates resilience to ocean acidification

Published 2 May 2024 Science Closed
Tags: biological response, chemistry, fish, laboratory, metals, multiple factors, physiology

Ocean acidification could modify the bioavailability and chemical properties of trace elements in seawater, which could affect their incorporation into the calcareous structures of marine organisms. Fish otoliths, biomineralized ear stones made by aragonite, are suspended within the endolymph fluid of teleosts, indicating that the elemental incorporation of otoliths might also be susceptible to ocean acidification. In this study, we evaluated the combined effects of CO₂-induced ocean acidification (pH 8.10, 7.70, and 7.30, corresponding to ocean acidification scenarios under the representative concentration pathway 8.5 model as projected by the Intergovernmental Panel on Climate Change) and water elemental concentrations of strontium (Sr) and barium (Ba; low, medium, and high) on elemental incorporation into otoliths of the flounder Paralichthys olivaceus at early life stages. Our results revealed that the elemental incorporation of Sr and Ba into otoliths was principally dependent on the corresponding water elemental concentrations rather than on ocean acidification. Moreover, the partition coefficients (D_Me) of Sr and Ba may stabilize after dynamic equilibrium is reached as the water elemental concentration increases, but are not affected by ocean acidification. Therefore, the incorporation of Sr and Ba into otoliths of the flounder at early life stages may not serve as an effective indicator of ocean acidification. In other words, the findings suggest that ocean acidification does not impact the incorporation of Sr and Ba incorporation into otoliths when tracing the temperature or salinity experiences of the flounder. Our findings will provide new knowledge for understanding the potential ecological effects of ocean acidification on the recruitment dynamics of fish species.

Continue reading ‘The incorporation of strontium and barium into the otoliths of the flounder Paralichthys olivaceus at early life stages demonstrates resilience to ocean acidification’

Interactive impacts of CO2-induced seawater acidification and cadmium exposure on antioxidant defenses of juvenile tongue sole Cynoglossus semilaevis

Published 8 April 2024 Science Closed
Tags: biological response, chemistry, fish, laboratory, metals, multiple factors

Highlights

Both SA and Cd induce oxidative stress and boost LPO in tongue sole.
SA amplifies oxidative stress and intensifies LPO in fish by interacting with Cd.
Antioxidants exhibit a higher sensitivity to SA compared to Cd exposure.
Escalating levels of stressors enhance the integrated antioxidant response.
Sensitive biomarkers for oxidant stress by SA and Cd exposure are identified.

Abstract

Antioxidant responses of juvenile sole exposed to seawater acidification (SA) and Cd were investigated. SA increased lipid peroxidation (LPO) in the fish, independent of Cd concentrations. Cd at medium and high levels inflated LPO under no or moderate SA conditions. This effect was absent under high SA levels, due to SA effect exceeding and obscuring Cd effect. SA and Cd collaborated to provoke LPO, with SOD and CAT being stimulated to defend against oxidative stress, while those related to GSH redox cycle were inhibited under SA exposure. Responses of GSH-related antioxidants to Cd impact varied contingent on their interactions with SA. This defensive strategy was insufficient to protect fish from increased LPO. Antioxidants responded more sensitively to SA than Cd exposure. GSH, GR, SOD and CAT are sensitive biomarkers for SA conditions. The findings offer insights into assessing fish’s antioxidant defense strategy under Cd and SA circumstances in natural habitats.

Continue reading ‘Interactive impacts of CO2-induced seawater acidification and cadmium exposure on antioxidant defenses of juvenile tongue sole Cynoglossus semilaevis’

Ocean acidification impact on the uptake of trace elements by mussels and their biochemical effects

Published 13 March 2024 Science Closed
Tags: biological response, chemistry, laboratory, metals, mollusks, morphology, multiple factors, North Atlantic, performance, physiology

Highlights

Copper and cerium bioavailability may increase under ocean acidification.
Ocean acidification impacts metal accumulation in mussel gills.
Biochemical responses in M. galloprovincialis altered by trace metals and OA.
Complex interplay of oxidative stress markers affected by OA and metals.

Abstract

This study delves into the intricate interplay between ocean acidification (OA), metal bioaccumulation, and cellular responses using mussels (Mytilus galloprovincialis) as bioindicators. For this purpose, environmentally realistic concentrations of isotopically labelled metals (Cd, Cu, Ag, Ce) were added to investigate whether the OA increase would modify metal bioaccumulation and induce adverse effects at the cellular level. The study reveals that while certain elements like Cd and Ag might remain unaffected by OA, the bioavailability of Cu and Ce could potentially escalate, leading to amplified accumulation in marine organisms. The present findings highlight a significant rise in Ce concentrations within different mussel organs under elevated pCO₂ conditions, accompanied by an increased isotopic fractionation of Ce (^140/142Ce), suggesting a heightened potential for metal accumulation under OA. The results suggested that OA influenced metal accumulation in the gills of mussels. Conversely, metal accumulation in the digestive gland was unaffected by OA. The exposure to both trace metals and OA affects the biochemical responses of M. galloprovincialis, leading to increased metabolic capacity, changes in energy reserves, and alterations in oxidative stress markers, but the specific effects on other biomarkers (e.g., lipid peroxidation, some enzymatic responses or acetylcholinesterase activity) were not uniform, suggesting complex interactions between the stressors and the biochemical pathways in the mussels.

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Biological and physiological responses of marine crabs to ocean acidification: a review

Published 14 February 2024 Science Closed
Tags: biological response, crustaceans, metals, morphology, mortality, multiple factors, oxygen, performance, physiology, review, salinity, temperature

Marine crabs play an integral role in the food chain and scavenge the debris in the ecosystem. Gradual increases in global atmospheric carbon dioxide cause ocean acidification (OA) and global warming that leads to severe consequences for marine organisms including crabs. Also, OA combined with other stressors like temperature, hypoxia, and heavy metals causes more severe adverse effects in marine crabs. The present review was made holistic discussion of information from 111 articles, of which 37 peer-reviewed original research papers reported on the effect of OA experiments and its combination with other stressors like heavy metals, temperature, and hypoxia on growth, survival, molting, chitin quality, food indices, tissue biochemical constituents, hemocytes population, and biomarker enzymes of marine crabs. Nevertheless, the available reports are still in the infancy of marine crabs, hence, this review depicts the possible gaps and future research needs on the impact of OA on marine crabs.

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A meta-analysis reveals global change stressors potentially aggravate mercury toxicity in marine biota

Published 22 January 2024 Science Closed
Tags: abundance, biological response, metals, modeling, morphology, mortality, multiple factors, otherprocess, performance, physiology, reproduction, review, temperature, toxicants

Growing evidence demonstrates that global change can modulate mercury (Hg) toxicity in marine organisms; however, the consensus on such effect is lacking. Here, we conducted a meta-analysis to evaluate the effects of global change stressors on Hg biotoxicity according to the IPCC projections (RCP 8.5) for 2100, including ocean acidification (−0.4 units), warming (+4 °C), and their combination (acidification-warming). The results indicated an overall aggravating effect (ln RR^Δ = −0.219) of global change on Hg toxicity in marine organisms, while the effect varied with different stressors; namely, acidification potentially alleviates Hg biotoxicity (ln RR^Δ = 0.117) while warming and acidification-warming have an aggravating effect (ln RR^Δ = −0.328 and −0.097, respectively). Moreover, warming increases Hg toxicity in different trophic levels, i.e., primary producers (ln RR^Δ = −0.198) < herbivores (ln RR^Δ = −0.320) < carnivores (ln RR^Δ = −0.379), implying increasing trends of Hg biomagnification through the food web. Notably, ocean hypoxia appears to boost Hg biotoxicity, although it was not considered in our meta-analysis because of the small sample size. Given the persistent global change and combined effects of these stressors in marine environments, multigeneration and multistressor research is urgently needed to fully disclose the impacts of global change on Hg pollution and its risk.

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Emergent properties of free-living nematode assemblages exposed to multiple stresses

Published 7 December 2023 Science Closed
Tags: abundance, biological response, BRcommunity, community composition, laboratory, mesocosms, metals, multiple factors, nematodes, otherprocess, sediment, South Atlantic, temperature

Highlights

Co-occurring stressors have significant interactive effects on nematode assemblages.
Metal contamination surpasses the effects of temperature rise and acidification.
Temperature rise intensified contamination effects on nematodes.
Acidification acted as a buffer to the contamination effects on nematodes.
Nematode genera showed variable responses to contamination.

Abstract

Biological communities are currently facing multi-stressor scenarios whose ecological impacts are challenging to estimate. In that respect, considering the complex nature of ecosystems and types and interaction among stressors is mandatory. Microcosm approaches using free-living nematode assemblages can effectively be used to assess complexity since they preserve the interactions inherent to complex systems when testing for multiple stress effects. In this study, we investigated the interaction effects of three stress factors, namely i-metallic mixture of Cu, Pb, Zn, and Hg (control [L0], low, [L1] and high [L2]), ii- CO₂-driven acidification (pH 7.6 and 8.0), and iii- temperature rise (26 and 28 °C), on estuarine free-living nematode assemblages. Metal contamination had the greatest influence on free-living nematode assemblages, irrespective of pH and temperature scenarios. Interestingly, whilst the most abundant free-living nematode genera showed significant decreases in their densities when exposed to contamination, other, less abundant, genera were apparently favored and showed significantly higher densities in contaminated treatments. The augmented densities of tolerant genera may be attributed to indirect effects resulting from the impacts of toxicity on other components of the system, indicating the potential for emergent effects in response to stress. Temperature and pH interacted significantly with contamination. Whilst temperature rise had potentialized contamination effects, acidification showed the opposite trend, acting as a buffer to the effects of contamination. Such results show that temperature rise and CO₂-driven acidification interact with contamination on coastal waters, highlighting the importance of considering the intricate interplay of these co-occurring stressors when assessing the ecological impacts on coastal ecosystems.

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The impact of ocean acidification and cadmium toxicity in the marine crab Scylla serrata: biological indices and oxidative stress responses

Published 23 October 2023 Science Closed
Tags: biological response, crustaceans, Indian, laboratory, metals, morphology, mortality, multiple factors, performance, physiology, toxicants

Highlights

Growth, food index, ALP, and heamocytes of crabs were decreased in OA + Cd exposure.
Antioxidants and metabolic enzymes were elevated in crabs under OA + Cd treatments.
Bioaccumulation of Cd was more in crabs subjected to OA + Cd.
OA + Cd interaction was higher on growth, protein, amino acid, and heamocytes of crabs.

Abstract

Ocean acidification (OA) and heavy metals pollution in marine environments are potentially threatening marine life. The interactive effect of OA and heavy metals could be more vulnerable to marine organisms than individual exposures. In the current study, the effect of OA on the toxicity of cadmium (Cd) in the crab Scylla serrata was evaluated. Crab instars (0.07 cm length and 0.1 g weight) were subjected to pH 8.2, 7.8, 7.6, 7.4, 7.2, and 7.0 with and without 0.01 mg l⁻¹ of Cd for 60 days. We notice a significant decrease in growth, molting, protein, carbohydrate, amino acid, lipid, alkaline phosphatase, and haemocytes of crabs under OA + Cd compared to OA treatment. In contrast, the growth, protein, amino acid, and haemocyte levels were significantly affected by OA, Cd, and its interactions (OA + Cd). However, superoxide dismutase, catalase, lipid peroxidation, glutamic oxaloacetate transaminase, glutamic pyruvate transaminase, and accumulation of Cd in crabs were considerably elevated in OA + Cd treatments compared to OA alone treatments. The present investigation showed that the effect of Cd toxicity might be raised under OA on S. serrata. Our study demonstrated that ocean acidification significantly affects the biological indices and oxidative stress responses of S. serrata exposed to Cd toxicity.

Continue reading ‘The impact of ocean acidification and cadmium toxicity in the marine crab Scylla serrata: biological indices and oxidative stress responses’

Ocean acidification increases copper accumulation and exacerbates copper toxicity in Amphioctopus fangsiao (Mollusca: Cephalopoda): a potential threat to seafood safety

Published 31 May 2023 Science Closed
Tags: biological response, growth, laboratory, metals, molecular biology, mollusks, morphology, multiple factors, North Pacific, performance, physiology

Highlights

A. fangsiao can adapt well to ocean acidification after 21-days experiment.
Copper accumulation in tissues showed increase in acidified seawater.
Copper exposure can influence the growth and feeding of A. fangsiao.
Acidification exacerbated the copper effect in metabolism and oxidative stress.
Copper exposure triggered DNA and protein and mitochondrial damage.

Abstract

Ocean acidification (OA) and trace metal pollutants coexist to exert combined effects on the functions and services of marine ecosystems. Increasing atmospheric carbon dioxide has caused a decrease in the pH of the ocean, affecting the bioavailability and speciation of trace metals and consequently altering metal toxicity in marine organisms. As an important trace metal functioned in hemocyanin, the richness of Copper (Cu) in octopuses is remarkable. Therefore, the biomagnification and bioaccumulation capacities of Cu in octopuses may be a non-negligible risk of contamination. Here, Amphioctopus fangsiao was continuously exposed to acidified seawater (pH 7.8) and copper (50 μg/L) to investigate the combined effect of ocean acidification and Cu exposure on marine mollusks. Our results showed that A. fangsiao could adapt well to ocean acidification after 21 days of the rearing experiment. However, the accumulation of Cu in A. fangsiao intestine increased significantly in acidified seawater under high levels of Cu stress. In addition, Cu exposure can influence the physiological function of A. fangsiao, including growth and feeding. This study also demonstrated that Cu exposure disturbed glucolipid metabolism and induced oxidative damage to intestine tissue, and ocean acidification further exacerbated these toxic effects. The obvious histological damage and microbiota alterations were also caused by Cu stress and its combined effect with ocean acidification. At the transcription level, we found numerous differentially expressed genes (DEGs) and significantly enriched KEGG pathways, involving glycolipid metabolism, transmembrane transport, glucolipid metabolism, oxidative stress, mitochondrial, protein and DNA damage, all revealing the strong toxicological synergetic effect of Cu and OA exposure and the molecular adaptation mechanism of A. fangsiao. Collectively, this study demonstrated that octopuses may withstand future ocean acidification conditions, however, the complex interactions of future OA and trace metal pollution need to be emphasized. OA can influence the toxicity of trace metals, inducing a potential threat to marine organism safety.

Continue reading ‘Ocean acidification increases copper accumulation and exacerbates copper toxicity in Amphioctopus fangsiao (Mollusca: Cephalopoda): a potential threat to seafood safety’

High and diurnally fluctuating carbon dioxide exposure produces lower mercury toxicity in a marine copepod

Published 19 May 2023 Science Closed
Tags: biological response, crustaceans, laboratory, metals, molecular biology, multiple factors, physiology, toxicants, zooplankton

Highlights

Elevated pCO₂ decreased Hg accumulation in Hg-treated T. japonicus.
Fluctuating elevated pCO₂ further decreased Hg bioaccumulation.
Hg exposure caused energy depletion and oxidative stress in T. japonicus.
Elevated pCO₂ initiated compensatory response in copepods to decrease Hg toxicity.
Fluctuating elevated pCO₂ presented more immune defense related genes/processes.

Abstract

Coastal waters have experienced fluctuations in partial pressure of carbon dioxide (pCO₂) and mercury (Hg) pollution, yet little is known concerning how natural pCO₂ fluctuations affect Hg biotoxicity. Here, a marine copepod Tigriopus japonicus was interactively exposed to different seawater pCO₂ (ambient 400, steady elevated 1000, and fluctuating elevated 1000 ± 600 μatm) scenarios and Hg (control, 2 μg/L) treatments for 7 d. The results showed that elevated pCO₂ decreased Hg bioaccumulation, and it was even more under fluctuating elevated pCO₂ condition. We found energy depletion and oxidative stress under Hg-treated copepods, while combined exposure initiated compensatory response to alleviate Hg toxicity. Intriguingly, fluctuating acidification presented more immune defense related genes/processes in Hg-treated copepods when compared to steady acidification, probably linking with the greater decrease in Hg bioaccumulation. Collectively, understanding how fluctuating acidification interacts with Hg contaminant will become more crucial in predicting their risks to coastal biota and ecosystems.

Continue reading ‘High and diurnally fluctuating carbon dioxide exposure produces lower mercury toxicity in a marine copepod’

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