Posts Tagged 'metals'

Simulating CO2 leakage from sub-seabed storage to determine metal toxicity on marine bacteria


  • Effects of CO2 leakage from CCS activities on marine bacteria were assessed.
  • Zn and Cd toxicity are evaluated under CO2 acidified conditions.
  • Negative responses because of the combination of metals and CO2 were observed.


CO2 storage in sub-seabed marine geological formations has been proposed as an adequate strategy to mitigate high CO2 concentration from the atmosphere. The lack of knowledge about the potential risks of this technology on marine bacteria population in presence of metals has lead us to perform laboratory-scale experiments in order to evaluate its consequences. Thus, the effects of Zn and Cd were studied under acid conditions on Roseobacter sp. and Pseudomonas litoralis. Bacterial abundance (cells mL− 1), growth rates (μ, h− 1), relative inhibitory effects of CO2 (RICO2), and production of Extracellular Polysaccharides Substances (EPS) (μg Glucose cells− 1) were evaluated. A decreasing exopolysaccharides (EPS) production was found under low pH. Bacterial abundance as well as growth rates showed negative effects. Data obtained in this work are useful to determine the potential effects associated with enrichment of CO2 and metals on the marine ecosystem.

Continue reading ‘Simulating CO2 leakage from sub-seabed storage to determine metal toxicity on marine bacteria’

Expected CO2-induced ocean acidification modulates copper toxicity in the green tide alga Ulva prolifera


  • The inhibition of Cu on growth and photosynthesis was reduced at moderate pCO2.
  • The inhibition of Cu on growth and photosynthesis was magnified at high pCO2.
  • Respiration and Chl a were enhanced by increased Cu at low and moderate pCO2 levels.
  • Shrank and branched thalli were induced by high Cu and pCO2.


Cu is considered to be toxic to macroalgae at higher levels. Ocean acidification can also alter the physiological performances of macroalgae. However, little is known regarding the interactive effects of Cu and ocean acidification on macroalgae. In this study, a green tide macroalga, Ulva prolifera, was cultured at the conditions of three levels of Cu (control, 0.5 μM, and 2 μM) and pCO2 (ambient, 1000 μatm, and 1400 μatm) to investigate the responses of U. prolifera to interaction of Cu exposure and ocean acidification. The relative growth rate of thalli decreased with the rise of Cu for all pCO2 conditions except the 1000 μatm pCO2. Compared with the control, 2 μM Cu reduced the net photosynthetic rate for all pCO2 conditions while 0.5 μM Cu only reduced it at 1400 μatm pCO2. The inhibition rate of Cu on the relative growth rate and net photosynthetic rate was reduced at 1000 μatm pCO2 but was magnified at 1400 μatm pCO2. Contrary to growth, the dark respiration rate was enhanced by 0.5 μM Cu at ambient pCO2 and by 2 μM Cu at ambient and 1000 μatm pCO2, although it was reduced by 2 μM Cu at 1400 μatm pCO2 compared to the control. The 0.5 μM Cu did not affect the relative electron transport rate (rETR) for any pCO2 condition but 2 μM Cu decreased it for all pCO2 conditions except 1000 μatm pCO2. The mute effect of 0.5 μM Cu on the net photosynthetic rate and rETR at ambient pCO2 may be due to more Chl a and Chl b being synthesized. In addition, 2 μM Cu and 1400 μatm pCO2 led to branched thalli, which may be a defense mechanism against the stress of high Cu and pCO2. Our data, for the first time, demonstrate that a modest increase of pCO2 can alleviate the toxicity of Cu to U. prolifera whilst a further increase exacerbates it. U. prolifera can respond to the stress of Cu pollution and ocean acidification via physiological and morphological alterations.

Continue reading ‘Expected CO2-induced ocean acidification modulates copper toxicity in the green tide alga Ulva prolifera’

Marine phytoplankton and the changing ocean iron cycle

The availability of the micronutrient iron governs phytoplankton growth across much of the ocean, but the global iron cycle is changing rapidly due to accelerating acidification, stratification, warming and deoxygenation. These mechanisms of global change will cumulatively affect the aqueous chemistry, sources and sinks, recycling, particle dynamics and bioavailability of iron. Biological iron demand will vary as acclimation to environmental change modifies cellular requirements for photosynthesis and nitrogen acquisition and as adaptive evolution or community shifts occur. Warming, acidification and nutrient co-limitation interactions with iron biogeochemistry will all strongly influence phytoplankton dynamics. Predicting the shape of the future iron cycle will require understanding the responses of each component of the unique biogeochemistry of this trace element to many concurrent and interacting environmental changes.

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Indirect effects of climate changes on cadmium bioavailability and biological effects in the Mediterranean mussel Mytilus galloprovincialis

Despite the great interest in the consequences of climate change on the physiological functioning of marine organisms, indirect and interactive effects of rising temperature and pCO2 on bioaccumulation and responsiveness to environmental pollutants are still poorly explored, particularly in terms of cellular mechanisms. According to future projections of temperature and pH/pCO2, this study investigated the main cellular pathways involved in metal detoxification and oxidative homeostasis in Mediterranean mussels, Mytilus galloprovincialis, exposed for 4 weeks to various combinations of two levels of pH/pCO2 (8.2/∼400 μatm and 7.4/∼3000 μatm), temperature (20 and 25 °C), and cadmium addition (0 and 20 μg/L). Bioaccumulation was increased in metal exposed organisms but it was not further modulated by different temperature and pH/pCO2 combinations. However, interactions between temperature, pH and cadmium had significant effects on induction of metallothioneins, responses of the antioxidant system and the onset of oxidative damages, which was tissue dependent. Multiple stressors increased metallothioneins concentrations in the digestive gland revealing different oxidative effects: while temperature and cadmium enhanced glutathione-dependent antioxidant protection and capability to neutralize peroxyl radicals, the metal increased the accumulation of lipid peroxidation products under acidified conditions. Gills did not reveal specific effects for different combinations of factors, but a general stress condition was observed in this tissue after various treatments. Significant variations of immune system were mainly caused by increased temperature and low pH, while co-exposure to acidification and cadmium enhanced metal genotoxicity and the onset of permanent DNA damage in haemocytes. Elaboration of the whole biomarker data in a cellular hazard index, corroborated the synergistic effects of temperature and acidification which increased the toxicological effects of cadmium. The overall results confirmed that climate change could influence ecotoxicological effects of environmental contaminants, highlighting the importance of a better knowledge of cellular mechanisms to understand and predict responsiveness of marine organisms to such multiple stressors.

Continue reading ‘Indirect effects of climate changes on cadmium bioavailability and biological effects in the Mediterranean mussel Mytilus galloprovincialis’

Responses of the sea anemone, Exaiptasia pallida, to ocean acidification conditions and zinc or nickel exposure

Ocean acidification, caused by increasing atmospheric carbon dioxide (CO2), is a growing concern in marine environments. Land-based sources of pollution, such as metals, have also been a noted problem; however, little research has addressed the combined exposure of both pollutants to coral reef organisms. In this study we examined tissue metal accumulation and physiological effects (activity of anti-oxidant enzymes, catalase and glutathione reductase) in the sea anemone, Exaiptasia pallida after exposure to increased CO2, as well as zinc (Zn) or nickel (Ni). After exposure to four concentrations (nominal values = control, 10, 50, 100 μg/L) of Zn or Ni over 7 days, both metals accumulated in the tissues of E. pallida in a concentration-dependent manner. Anemones exposed to elevated CO2 (1000 ppm) accumulated significant tissue burdens of Zn or Ni faster (by 48 h) than those exposed to the same metal concentrations at ambient CO2. No differences were observed in catalase activity due to Zn exposure; however, 50 μg/L Ni caused a significant increase in catalase activity at ambient CO2. No significant effect on catalase activity from CO2 exposure alone was observed. Glutathione reductase activity was affected by increased Zn or Ni exposure and those effects were influenced by increased CO2. Results of this study provide insight into the toxic mechanisms and environmental implications of CO2 and Zn or Ni exposure to the cnidarian E. pallida.

Continue reading ‘Responses of the sea anemone, Exaiptasia pallida, to ocean acidification conditions and zinc or nickel exposure’

Effects of ocean acidification, temperature and copper on the development of early life stages of the native kelp Macrocystis Pyrifera and the invasive kelp Undaria Pinnatifida from Southern New Zealand

Anthropogenic activities have increased atmospheric CO2 concentrations from pre-industrial concentrations of 280 ppm to current values of 400 ppm. These atmospheric emissions of CO2 are responsible for the ongoing increase in seawater temperature and the reduction of pH in the ocean’ surface, phenomena known as ocean warming (OW) and ocean acidification (OA), respectively. Model-based projections indicate that the global ocean surface temperature will increase by 4°C whereas the pH will decrease from a current 8.10 to 7.74 by 2100. However, these two global events are not occurring in isolation because anthropogenic activities also threatens coastal environments at local levels. For instance, in coastal environments, natural concentrations of copper are low but are increasing due to human industrialization. In addition, the speciation and bioavailability of copper in seawater is highly dependent on seawater chemistry. Therefore, reductions in seawater pH due to OA will increase the toxic, free ionic form of copper in oceans by 20% by the end of the current century. These abiotic changes can have important impacts on marine biota and ecosystems. Fleshy (non-calcifying) macroalgae such as those that belong to the Order Laminariales are important components of coastal environments. Macroalgae, as sessile organisms, are exposed to constant changes in abiotic factors and the community dynamics (e.g., growth and reproduction) depend on their tolerance to stress. Despite their importance, few studies have focused on the effects of OW, OA and/or copper pollution on fleshy macroalgae and even less have focused on their early life stages. Early life stages have been reported to be the most sensitive phase of the macroalgal life cycle to stressors. Therefore, the main purpose of this work was to evaluate the separate and interactive effects of seawater temperature, pH and copper concentration on the development of microscopic stages of the native kelp M. pyrifera and the invasive kelp U. pinnatifida from southern New Zealand.The first result of this work was that, in M. pyrifera, sporogenesis occurred in basal sporophylls (specialized reproductive laminae) as well as in non-reproductive laminae such as pneumatocyst-bearing adult blade and young apical scimitars. The sorus surface area was greater on sporophylls (57%) than in adult blades and young scimitars (25%). Meiospore release was greater in apical scimitars, followed by adult blades and sporophylls. However, germination of meiospores from different laminae was not significantly different, indicating that meiospores produced in all types of fertile laminae were equally viable.

The first climate change-related experiment consisted of monitoring meiospore development of M. pyrifera and U. pinnatifida cultured under four seawater pH treatments (pH 7.20, extreme OA predicted for 2300; pH 7.65, OA predicted for 2100; pH 8.01, ambient pH; and pH 8.40, pre-industrial pH) for 15 days. Reduced seawater pH (7.20 and 7.65) had no effects on meiospore germination but had positive effects on germling growth rates and gametophyte size of both species compared to higher pH (8.01 and 8.40). Gametophyte sex ratio was biased towards females under all pH treatments. Germling growth rate under OA was significantly higher in M. pyrifera compared to U. pinnatifida but gametophyte development was equal for both kelps under all seawater pH treatments, indicating that the microscopic stages of the native M. pyrifera and the invasive U. pinnatifida will respond similarly to OA.

The second experiment climate change-related experiment consisted of monitoring meiospore development of M. pyrifera and U. pinnatifida cultured under four seawater pH treatments (pH 7.20, 7.65, 8.03, and 8.40) and two temperature treatments (12°C, ambient temperature; and 16°C, OW predicted for 2100) for 15 days. Reduced seawater pH and elevated temperature had no effects on meiospore development and positive effects on germling growth rates and gametophyte size of both species compared to higher pH (8.01 and 8.40) and lower temperature (12°C), whereas gametophyte sex ratio was not affected by the interaction between the two factors. Despite some small differences between species, results of this experiment suggest that microscopic stages of the native M. pyrifera and the invasive U. pinnatifida will respond similarly to OA and OW.

The single effects of the local stressor, copper pollution, on the development of M. pyrifera and U. pinnatifida meiospore were examined. After settlement, meiospores of both kelps were exposed to five nominal copper treatments (control, 100, 200, 300 and 400 µg L-1 Cu) for 9 days. Analyses of total dissolved copper (CuT) concentrations in the blanks showed that nominal copper concentrations were reduced to 54, 91, 131 and 171 µg L-1 CuT (i.e., > 50% of the CuT was adsorbed onto the culture vessel walls). In the media with meiospores, the CuT also decreased: to 39, 86, 97 and 148 µg L-1 CuT in M. pyrifera, and to 39, 65, 97 and 146 µg L-1 CuT in U. pinnatifida (i.e., 6 – 15% of the dissolved copper was adsorbed by the cells). Meiospore germination decreased with increasing copper concentrations but gametogenesis was arrested under all copper treatments. The effective copper concentration causing 50% of arrested germination (Cu EC50) was higher for U. pinnatifida (231 µg L-1 CuT) than for M. pyrifera (157 µg L-1 CuT), suggesting ecological success for the invasive species in copper polluted environments; however, the subsequent inhibition of gametogenesis under all copper treatments indicated no difference in copper tolerance between both kelp early life stages.

The reduction of CuT during the previous experiment occurred because copper might be adsorbed onto glass and/or plastic and this can be avoided using a proper trace metal clean procedure. Therefore, a review on the methodologies used in the literature on copper ecotoxicology of marine macro- and microalgae, specifically the use of trace metal clean procedures such as the labware used (glassware vs plasticware), methods of cleaning the labware (acid soaking and ultrapure water rinsing), stock solution preparation (copper source and acidification), and measurement and reporting of dissolved copper concentrations was performed. The main results of this review were that 50% of the articles did not specify the laboratory–ware, 25% used glassware and 25% plasticware; only ~30% of the studies specified cleaning protocols for labware to remove trace metal impurities; the copper form used to prepare the stock solutions was specified in ~80% of studies but acidification to stabilize the dissolved copper was performed in only ~20%; and the dissolved copper concentration was measured in only ~30% of studies. Based on these finding, a trace metal procedure was recommended for conducting copper ecotoxicological studies.

A four-factor experiment was performed to investigate the interactive effects of OA, OW and copper pollution on the meiospore development of M. pyrifera and U. pinnatifida. Meiospores of both species were cultured under two seawater pH treatments (7.65 and 8.16), and two temperature treatments (12 and 16°C), and to the species-specific Cu-EC50 for 18 days. In both species, meiospore germination and germling growth rates significantly decreased in the copper treatment, irrespective of pH and temperature whereas gametophyte development for both species was inhibited by copper in all pH and temperature treatments. These results suggest that a local stressor (e.g., copper) is more important to the development of microscopic stages of M. pyrifera and U. pinnatifida than global climate change factors.

In summary, results of this study indicate that meiospore development of M. pyrifera and U. pinnatifida will be able to tolerate future OA and OW. That tolerance might be related to: 1) macro- and microscopic stages of both kelps being able to use HCO3- and CO2 to support photosynthesis, therefore, the higher CO2(aq) availability due to OA (pH 7.20 to 7.65) will not affect their physiology; and 2) both M. pyrifera and U. pinnatifida have a wide temperature tolerance (4 to 30C°) which may allow them to perform well in a future warmer ocean (+ 4C°). In contrast, relatively high copper concentrations inhibited meiospore development of both kelp species. This finding indicates that local drivers (e.g., copper pollution) may be more important to physiological processes during meiospore development than global climate change factors. Furthermore, the responses of meiospores to the experimental abiotic factors (i.e., OA, OW and Cu) were similar between the study species, indicating that the invasive U. pinnatifida is unlikely to have an advantage over the native M. pyrifera in natural coastal environments.

Continue reading ‘Effects of ocean acidification, temperature and copper on the development of early life stages of the native kelp Macrocystis Pyrifera and the invasive kelp Undaria Pinnatifida from Southern New Zealand’

Lethal and sub-lethal effects of elevated CO2 concentrations on marine benthic invertebrates and fish

Concern about leakage of carbon dioxide (CO2) from deep-sea storage in geological reservoirs is increasing because of its possible adverse effects on marine organisms locally or at nearby coastal areas both in sediment and water column. In the present study, we examined how elevated CO2 affects various intertidal epibenthic (benthic copepod), intertidal endobenthic (Manila clam and Venus clam), sub-tidal benthic (brittle starfish), and free-living (marine medaka) organisms in areas expected to be impacted by leakage. Acute lethal and sub-lethal effects were detected in the adult stage of all test organisms exposed to varying concentrations of CO2, due to the associated decline in pH (8.3 to 5.2) during 96-h exposure. However, intertidal organisms (such as benthic copepods and clams) showed remarkable resistance to elevated CO2, with the Venus clam being the most tolerant (LpH50 = 5.45). Sub-tidal species (such as brittle starfish [LpH50 = 6.16] and marine medaka [LpH50 = 5.91]) were more sensitive to elevated CO2 compared to intertidal species, possibly because they have fewer defensive capabilities. Of note, the exposure duration might regulate the degree of acute sub-lethal effects, as evidenced by the Venus clam, which showed a time-dependent effect to elevated CO2. Finally, copper was chosen as a model toxic element to find out the synergistic or antagonistic effects between ocean acidification and metal pollution. Combination of CO2 and Cu exposure enhances the adverse effects to organisms, generally supporting a synergistic effect scenario. Overall, the significant variation in the degree to which CO2 adversely affected organisms (viz., working range and strength) was clearly observed, supporting the general concept of species-dependent effects of elevated CO2.

Continue reading ‘Lethal and sub-lethal effects of elevated CO2 concentrations on marine benthic invertebrates and fish’

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Ocean acidification in the IPCC AR5 WG II

OUP book