Archive for April, 2020



The effect of elevated pCO2 on cadmium resistance of a globally important diatom

Highlights

• Elevated pCO2 alleviated Cd toxicity to P. tricornutum;

• P. tricornutum showed adaptation responses to OA after long-term selection;

• Long-term selected lineages expressed a specific Cd detoxification strategy;

• OA reduced Cd accumulation across trophic levels.

Abstract

Cadmium (Cd) pollution is a widespread threat to marine life, and ongoing ocean acidification (OA) is predicted to impact bio-toxicity of Cd compounds. However, the cascading effects of changed Cd toxicity to marine primary producers are not well characterized. Here, we studied the impact of OA on Cd toxicity responses in a globally important diatom Phaeodactylum tricornutum under both ambient and elevated pCO2 conditions. We found that increased pCO2 alleviated the impact of additive Cd toxicity on P. tricornutum not only under controlled indoor experiments but also in outdoor mesocosm experiments that reflect more natural growth conditions. Transcriptome analysis suggested that genes involved in Cd efflux and phytochelatin production were up-regulated and genes involved in Cd influx were down-regulated in long-term selected lineages under elevated pCO2. We further found a significant reduction of Cd transfer across trophic level, when the scallop Argopecten irradians was fed with Cd-exposed P. tricornutum previously cultured under elevated pCO2. Our results indicate that after long-term selection of P. tricornutum exposed to future OA conditions (i.e. elevated pCO2), the diatom alters its Cd detoxification strategy, which could have broader impacts on the bio-geochemical cycle of Cd in the marine ecosystem.

Continue reading ‘The effect of elevated pCO2 on cadmium resistance of a globally important diatom’

Effects of ocean acidification on Antarctic marine organisms: a meta‐analysis

Southern Ocean waters are among the most vulnerable to ocean acidification. The projected increase in the CO2 level will cause changes in carbonate chemistry that are likely to be damaging to organisms inhabiting these waters. A meta‐analysis was undertaken to examine the vulnerability of Antarctic marine biota occupying waters south of 60°S to ocean acidification. This meta‐analysis showed that ocean acidification negatively affects autotrophic organisms, mainly phytoplankton, at CO2 levels above 1,000 μatm and invertebrates above 1,500 μatm, but positively affects bacterial abundance. The sensitivity of phytoplankton to ocean acidification was influenced by the experimental procedure used. Natural, mixed communities were more sensitive than single species in culture and showed a decline in chlorophyll a concentration, productivity, and photosynthetic health, as well as a shift in community composition at CO2 levels above 1,000 μatm. Invertebrates showed reduced fertilization rates and increased occurrence of larval abnormalities, as well as decreased calcification rates and increased shell dissolution with any increase in CO2 level above 1,500 μatm. Assessment of the vulnerability of fish and macroalgae to ocean acidification was limited by the number of studies available. Overall, this analysis indicates that many marine organisms in the Southern Ocean are likely to be susceptible to ocean acidification and thereby likely to change their contribution to ecosystem services in the future. Further studies are required to address the poor spatial coverage, lack of community or ecosystem‐level studies, and the largely unknown potential for organisms to acclimate and/or adapt to the changing conditions.

Continue reading ‘Effects of ocean acidification on Antarctic marine organisms: a meta‐analysis’

The effects of elevated temperature and PCO2 on the energetics and haemolymph pH homeostasis of juveniles of the European lobster, Homarus gammarus

Regulation of extracellular acid–base balance, while maintaining energy metabolism, is recognised as an important aspect when defining an organism’s sensitivity to environmental changes. This study investigated the haemolymph buffering capacity and energy metabolism (oxygen consumption, haemolymph [l-lactate] and [protein]) in early benthic juveniles (carapace length <40 mm) of the European lobster, Homarus gammarus, exposed to elevated temperature and PCO2. At 13°C, H. gammarus juveniles were able to fully compensate for acid–base disturbances caused by the exposure to elevated seawater PCO2 at levels associated with ocean acidification and carbon dioxide capture and storage (CCS) leakage scenarios, via haemolymph [HCO3−] regulation. However, metabolic rate remained constant and food consumption decreased under elevated PCO2, indicating reduced energy availability. Juveniles at 17°C showed no ability to actively compensate haemolymph pH, resulting in decreased haemolymph pH particularly under CCS conditions. Early benthic juvenile lobsters at 17°C were not able to increase energy intake to offset increased energy demand and therefore appear to be unable to respond to acid–base disturbances due to increased PCO2 at elevated temperature. Analysis of haemolymph metabolites suggests that, even under control conditions, juveniles were energetically limited. They exhibited high haemolymph [l-lactate], indicating recourse to anaerobic metabolism. Low haemolymph [protein] was linked to minimal non-bicarbonate buffering and reduced oxygen transport capacity. We discuss these results in the context of potential impacts of ongoing ocean change and CCS leakage scenarios on the development of juvenile H. gammarus and future lobster populations and stocks.

Continue reading ‘The effects of elevated temperature and PCO2 on the energetics and haemolymph pH homeostasis of juveniles of the European lobster, Homarus gammarus’

Ocean acidification and dynamic energy budget models: parameterisation and simulations for the green-lipped mussel

Highlights

• A dynamic energy budget (DEB) model for the green-lipped mussel.

• Experiments at future projected pCO2/pH levels, simulating ocean acidification (OA).

• Higher respiration rates and less growth at elevated pCO2 (reduced pH).

• Key DEB parameters modified for OA scenarios projected for 2050 and 2100.

• DEB predicts reduced growth, biomass and reproductive capacity with OA.

Abstract

Ocean acidification (OA), the change in ocean chemistry caused by carbon dioxide emissions, poses a serious imminent threat to marine organisms, especially those with calcium carbonate shells. The green-lipped mussel (Perna canaliculus), endemic to New Zealand, is common in coastal ecosystems and is an economically important aquaculture species. As a step towards supporting aquaculture management in a changing environment, we used a dynamic energy budget (DEB) model to investigate the potential influence of OA on growth and reproduction of the mussel. Zero-variate and growth data from local mussel farms were used to parameterise the model with the AmP method. The parameter estimation showed an acceptable goodness of fit, with a low mean relative error of 0.143 and the symmetric mean squared error of 0.125. The model was subsequently modified to estimate parameter values under OA conditions, based on data obtained from laboratory experiments where mussels were grown at future projected reduced pH (elevated pCO2) levels. The maintenance ([ṗM]) and volume-specific cost for growth ([EG]) were identified as the key parameters in response to OA. The model was then applied to simulate mussel energetics under pCO2 scenarios projected for 2050 and 2100. The model predicts that decreasing pH would cause reductions in shell length growth, flesh weight and reproductive capacity. As well as providing a quantitative tool for understanding the influence of OA on mussel physiology, this DEB model is also an important component of individual-based population and ecosystem models, enabling simulation of complex population and ecosystem level responses to OA.

Continue reading ‘Ocean acidification and dynamic energy budget models: parameterisation and simulations for the green-lipped mussel’

Energetic context determines species and community responses to ocean acidification

Physiological responses to ocean acidification are thought to be related to energetic trade‐offs. Although a number of studies have proposed that negative responses to low pH could be minimized in situations where food resources are more readily available, evidence for such effects on individuals remain mixed, and the consequences of such effects at the community level remain untested. We explored the potential for food availability and diet quality to modify the effects of acidification on developing marine fouling communities in field‐deployed mesocosms by supplementing natural food supply with one of two species of phytoplankton, differing in concentration of fatty acids. After twelve weeks, no species demonstrated the interactive effects generally predicted in the literature, where a positive overall effect of diet mitigated the negative overall effects of acidification. Rather, for some species, additional food supply appeared to bring out or exacerbate the negative effects of low pH. Community richness and structure were only altered by acidification, while space occupation and evenness reflected patterns of the most dominant species. Importantly, we find that acidification stress can increase the relative abundance of invasive species, even under resource conditions that otherwise prevented invasive species establishment. Overall, the proposed hypothesis regarding the ability for food addition to mitigate the negative effects of acidification is thus far not widely supported at species or community levels. It is clear that acidification is a strong driving force in these communities but understanding underlying energetic and competitive context is essential to developing mechanistic predictions for climate change responses.

Continue reading ‘Energetic context determines species and community responses to ocean acidification’

Rising carbon dioxide levels will change marine habitats and fish communities

Rising carbon dioxide in the atmosphere and the consequent changes created through ocean acidification will cause severe ecosystem effects, impacting reef-forming habitats and the associated fish, according to new research.

Using submerged natural CO2 seeps off the Japanese Island of Shikine, an international team of marine biologists showed that even slightly higher CO2 concentrations than those existing today may cause profound changes in marine habitats and the fish that rely on them.

Writing in Science of The Total Environment, researchers from the Universities of Palermo (Italy), Tsukuba (Japan) and Plymouth showed that under elevated dissolved CO2 conditions, habitats are dominated by few ephemeral algae.

Continue reading ‘Rising carbon dioxide levels will change marine habitats and fish communities’

Effect of seawater acidity on the initial development of Kumamoto oyster larvae Crassostrea sikamea (Amemiya, 1928)

The oceans have absorbed more than 40% of the carbon dioxide (CO2) generated by anthropogenic activities, causing a decrease in the average pH of 0.1 units in seawater since preindustrial times. This phenomenon has been called “ocean acidification.” This change poses serious threats to the cultivation of oysters and especially to larval and spat production, activities carried out in coastal and estuarine areas, where pH levels are currently below the IPCC scenario for the year 2100 of pH = 7.8. The goal of the present work was to experimentally evaluate the effect of simulated acidification (pH 7.39 ± 0.04) on the culture in a short-term trial of Kumamoto oyster larvae Crassostrea sikamea taking the current ocean pH conditions (pH 8.116 ± 0.023) as a reference. The evaluation was carried out in an experimental system with continuous water flow and pH manipulation by CO2 bubbling. Veliger larvae (6-day-old postspawn) were cultured at a density of six larvae mL–1 and fed with a monoalgal diet based on Isochrysis galbana at 30,000 cells mL–1. Mortality (%) and growth (shell length in µm) were evaluated, and damage to larval morphology (determined using scanning electron microscopy) and Ca2+ contents in the shells (%) were quantified by X-ray fluorescence. The results show a high sensitivity of C. sikamea veliger larvae to low pH levels with negative impacts on growth and survival, decreases in the Ca2+ concentrations of the shells, and the presence of morphological anomalies during the prodissoconch I stage, which were observed after the first 24 h of cultivation in experimental conditions and became progressively more evident, especially by the sixth day of culture. Acute exposure to a low pH and a saturation of aragonite (Ωar) <1 caused poor calcification in C. sikamea larvae, causing negative effects on larvae, such as shell lesions during development, smaller larvae, and higher mortality and relation to a control pH.

Continue reading ‘Effect of seawater acidity on the initial development of Kumamoto oyster larvae Crassostrea sikamea (Amemiya, 1928)’

Systems and methods for determining carbon system parameters of water (United States Patent)

Inventors: Robert Howard Byrne

In one embodiment, determining carbon system parameters of water includes measuring the pH of a first subsample of the water using a spectrophotometer, adding nitric acid as a titrant to a second subsample of the water to obtain a titrated subsample, measuring a concentration of added nitric acid in the titrated subsample using a spectrophotometer, measuring the pH of the titrated subsample using a spectrophotometer, and calculating one or more unknown carbon system parameters using the pH of the first subsample, the pH of the titrated subsample, and the concentration of added nitric acid of the titrated subsample.

Continue reading ‘Systems and methods for determining carbon system parameters of water (United States Patent)’

Impacts of elevated pCO2 on Mediterranean mussel (Mytilus galloprovincialis): metal bioaccumulation, physiological and cellular parameters

Highlights

• Elevated pCO2 did not impact 110mAg bioconcentration in juvenile and adult mussels.

• Seawater acidification increased 109Cd bioconcentration in juvenile mussels but not in adults.

• Eighty-two days of elevated pCO2 decreased feeding rate and haemocyte survival.

• Lysosomal membrane stability in mussels remained unaffected by elevated pCO2.

• Circulating cell-free protein and nucleic acids (ccf-DNA, ccf-RNA, ccf-miRNA) levels in mussels were not impacted by seawater acidification.

Abstract

Ocean acidification alters physiology, acid-base balance and metabolic activity in marine animals. Accordingly, near future elevated pCO2 conditions could be expected to influence the bioaccumulation of metals, feeding rate and immune parameters in marine mussels. To better understand such impairments, a series of laboratory-controlled experiment was conducted by using a model marine mussel, Mytilus galloprovincialis. The mussels were exposed to three pH conditions according to the projected CO2 emissions in the near future (one ambient: 8.10 and two reduced: 7.80 and 7.50). At first, the bioconcentration of Ag and Cd was studied in both juvenile (2.5 cm) and adult (5.1 cm) mussels by using a highly sensitive radiotracer method (110mAg and 109Cd). The uptake and depuration kinetics were followed 21 and 30 days, respectively. The biokinetic experiments demonstrated that the effect of ocean acidification on bioconcentration was metal-specific and size-specific. The uptake, depuration and tissue distribution of 110mAg were not affected by elevated pCO2 in both juvenile and adult mussels, whereas 109Cd uptake significantly increased with decreasing pH in juveniles but not in adults. Regardless of pH, 110mAg accumulated more efficiently in juvenile mussels than adult mussels. After executing the biokinetic experiment, the perturbation was sustained by using the same mussels and the same experimental set-up, which enabled us to determine filtration rate, haemocyte viability, lysosomal membrane stability, circulating cell-free nucleic acids (ccf-NAs) and protein (ccf-protein) levels. The filtration rate and haemocyte viability gradually decreased by increasing the pCO2 level, whereas the lysosomal membrane stability, ccf-NAs, and ccf-protein levels remained unchanged in the mussels exposed to elevated pCO2 condition for eighty-two days. Considering these, this study suggests that acidified seawater partially shift metal bioaccumulation, physiological and cellular parameters in the mussel Mytilus galloprovincialis.

Continue reading ‘Impacts of elevated pCO2 on Mediterranean mussel (Mytilus galloprovincialis): metal bioaccumulation, physiological and cellular parameters’

High-resolution carbonate dynamics of Netarts Bay, OR from 2014 – 2019

Netarts Bay is a shallow, temperate, tidal lagoon located on the northern coast of Oregon and site of the Whiskey Creek Shellfish Hatchery (WCSH). Data collected with an automated flow-through system installed at WCSH capable of high-resolution (1 Hz) pCO2 and hourly TCO2 measurements, with measurement uncertainties of <2.0% and 0.5%, respectively, is analyzed over the 2014-2019 interval. These measurements provide total constraint on the carbonate system, allowing calculation of carbonate variables such as pHt, alkalinity, and carbonate mineral saturation states. Nearly 70% of the bay’s water is drained during each tide cycle, and in-bay fresh water sources are limited to small perennial streams or direct precipitation via high-rainfall events. Summer upwelling, wintertime downwelling, and in-situ bay biogeochemistry represent significant modes of the observed variability in carbonate dynamics. Summer upwelling is associated with large amplitude diel pCO2 variability, elevated TCO2 and alkalinity, but weak variability in salinity. Wintertime downwelling is associated with bay freshening by both local and remote sources, a strong tidal signature in salinity, TCO2, and alkalinity, with diel pCO2 variability much less amplified when compared to summer. Further, analysis of alkalinity-salinity relationships suggests multiple and discrete water masses inhabiting the bay during one year: mixing of end-members associated with direct precipitation, coastal rivers, southward displacement of the Columbia River plume, California Current surface and deep upwelled waters. The importance of in-bay processes such as net community metabolism during intervals of high productivity are apparent. These direct measurements of pCO2 and TCO2 have proved useful to local hatchery owners who have monitored intake waters following historic seed-production failures related to high-CO2 conditions exacerbated by ocean acidification. Continued monitoring efforts will produce baseline measurements necessary to understand how future warming and ocean acidification will impact our sensitive coastal environments.

Continue reading ‘High-resolution carbonate dynamics of Netarts Bay, OR from 2014 – 2019’


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