Archive for April, 2016



Pinctada margaritifera responses to temperature and pH: Acclimation capabilities and physiological limits

The pearl culture is one of the most lucrative aquacultures worldwide. In many South Pacific areas, it depends on the exploitation of the pearl oyster Pinctada margaritifera and relies entirely on the environmental conditions encountered in the lagoon. In this context, assessing the impact of climatic stressors, such as global warming and ocean acidification, on the functionality of the resource in terms of renewal and exploitation is fundamental. In this study, we experimentally addressed the impact of temperature (22, 26, 30 and 34 °C) and partial pressure of carbon dioxide pCO2 (294, 763 and 2485 μatm) on the biomineralization and metabolic capabilities of pearl oysters. While the energy metabolism was strongly dependent on temperature, results showed its independence from pCO2 levels; no interaction between temperature and pCO2 was revealed. The energy metabolism, ingestion, oxygen consumption and, hence, the scope for growth (SFG) were maximised at 30 °C and dramatically fell at 34 °C. Biomineralization was examined through the expression measurement of nine mantle’s genes coding for shell matrix proteins involved in the formation of calcitic prisms and/or nacreous shell structures; significant changes were recorded for four of the nine (Pmarg-Nacrein A1, Pmarg-MRNP34, Pmarg-Prismalin 14 and Pmarg-Aspein). These changes showed that the maximum and minimum expression of these genes was at 26 and 34 °C, respectively. Surprisingly, the modelled thermal optimum for biomineralization (ranging between 21.5 and 26.5 °C) and somatic growth and reproduction (28.7 °C) appeared to be significantly different. Finally, the responses to high temperatures were contextualised with the Intergovernmental Panel on Climate Change (IPCC) projections, which highlighted that pearl oyster stocks and cultures would be severely threatened in the next decade.

Continue reading ‘Pinctada margaritifera responses to temperature and pH: Acclimation capabilities and physiological limits’

Reduced pH affects pulsing behaviour and body size in ephyrae of the moon jellyfish, Aurelia aurita

Our understanding of how reduced seawater pH affects the behaviour and growth of scyphozoan jellyfish is poor. Here, we investigated the effects of simulated Ocean Acidification (OA) (pH = 7.6 for 7 d) on pulsing behaviour (as an index of swimming behaviour) and aspects of the morphology of ephyrae of the moon jellyfish Aurelia aurita. Ephyrae exposed to reduced pH had a significantly smaller surface area, central disc area, and lappet length and width than controls. Pulsation rate was significantly lower, and the mean pulse-to-pulse period shorter, in the reduced pH treatment. There was, however, no significant treatment effect on either the maximum or minimum pulse-to-pulse period, suggesting that the ability for rapid pulsations was maintained. Ephyrae from the reduced pH treatment displayed a more variable pulsation behaviour, with an elevated standard deviation and root mean square of successive difference (RMSSD) in pulse-to-pulse period. In summary, reduced pH simulating future predicted Ocean Acidification conditions, had important effects on aspects of swimming behaviour and size of A. aurita ephyra, which may have consequences for survival and the population dynamics of field populations.

Continue reading ‘Reduced pH affects pulsing behaviour and body size in ephyrae of the moon jellyfish, Aurelia aurita’

New edition of the “OA-ICC Highlights”

OA-ICC Highlights January-March 2016 final proof

The new edition of the “OA-ICC Highlights” summarizes the the project’s main activities and achievements over the period January – March 2016. The information is structured around the OA-ICC three major areas of work: science, capacity building and communication.

The “OA-ICC Highlights” is a quarterly newsletter and all previous editions can be viewed here.

Warning bells: Pollution turns sea acidic, threatens fish, corals

There is a new threat to the country’s coastal waters, already struggling to cope with pollution from heightened industrial activity. The increasing amounts of carbondioxide getting dissolved in the water is acidifying it that could destroy corals reefs and reduce fish population, warn oceanographers. While most of the carbondioxide released annually by the consumption of fossil fuels such as coal, oil, and natural gas contributes to global warming, about onethird gets dissolved in the oceans, causing the more serious problem of acidification, said former Zoological Survey of India director K Venkataraman.

Organisms such as corals and calcifying planktons, key to the ocean’s ecosystem with their ability to grow shells, will be unable to perform their ‘magic’ in waters with acidic content, a situation that could prove hazardous in the long run, Venkatraman said. Similarly, marshlands, mangroves and seagrass, termed ‘blue carbon’ for their effective high rates of annual carbon sequestration, will not be able to store carbon for longer periods of time because of such waters, he added.

Continue reading ‘Warning bells: Pollution turns sea acidic, threatens fish, corals’

Combined effects of seawater acidification and salinity changes in Ruditapes philippinarum

Due to human activities, predictions for the coming years indicate increasing frequency and intensity of extreme weather events (rainy and drought periods) and pollution levels, leading to salinity shifts and ocean acidification. Therefore, several authors have assessed the effects of seawater salinity shifts and pH decrease on marine bivalves, but most of the studies evaluated the impacts of both factors independently. Since pH and salinity may act together in the environment, and their impacts may differ from their effects when acting alone, there is an urgent need to increase our knowledge when these environmental changes act in combination. Thus, the present study assessed the effects of seawater acidification and salinity changes, both acting alone and in combination, on the physiological (condition index, Na and K concentrations) and biochemical (oxidative stress related biomarkers) performance of R. philippinarum. For that, specimens of R. philippinarum were exposed for 28 days to the combination of different pH levels (7.8 and 7.3) and salinities (14, 28 and 35). The results obtained showed that under control pH (7.8) and low salinity (14) the physiological status and biochemical performance of clams was negatively affected, revealing oxidative stress. However, under the same pH but at salinities 28 and 35 clams were able to maintain/regulate their physiological status and biochemical performance. Moreover, our findings showed that clams under low pH (7.3) and different salinities were able to maintain their physiological status and biochemical performance, suggesting that the low pH tested may mask the negative effects of salinity. Our results further demonstrated that, in general, at each salinity, similar physiological and biochemical responses were found in clams under both tested pH levels. Also, individuals under low pH (salinities 14, 28 and 25) and exposed to pH 7.8 and salinity 28 (control) tend to present a similar response pattern. These results indicate that pH may have less impact on clams than salinity. Thus, our findings point out that the predicted increase of CO2 in seawater and consequently seawater acidification will have fewer impacts on physiological and biochemical performance of R. philippinarum clams than salinity shifts.

Continue reading ‘Combined effects of seawater acidification and salinity changes in Ruditapes philippinarum’

Ocean acidification affects the phyto-zoo plankton trophic transfer efficiency

The critical role played by copepods in ocean ecology and biogeochemistry warrants an understanding of how these animals may respond to ocean acidification (OA). Whilst an appreciation of the potential direct effects of OA, due to elevated pCO2, on copepods is improving, little is known about the indirect impacts acting via bottom-up (food quality) effects. We assessed, for the first time, the chronic effects of direct and/or indirect exposures to elevated pCO2 on the behaviour, vital rates, chemical and biochemical stoichiometry of the calanoid copepod Acartia tonsa. Bottom-up effects of elevated pCO2 caused species-specific biochemical changes to the phytoplanktonic feed, which adversely affected copepod population structure and decreased recruitment by 30%. The direct impact of elevated pCO2 caused gender-specific respiratory responses in A.tonsa adults, stimulating an enhanced respiration rate in males (> 2-fold), and a suppressed respiratory response in females when coupled with indirect elevated pCO2 exposures. Under the combined indirect+direct exposure, carbon trophic transfer efficiency from phytoplankton-to-zooplankton declined to < 50% of control populations, with a commensurate decrease in recruitment. For the first time an explicit role was demonstrated for biochemical stoichiometry in shaping copepod trophic dynamics. The altered biochemical composition of the CO2-exposed prey affected the biochemical stoichiometry of the copepods, which could have ramifications for production of higher tropic levels, notably fisheries. Our work indicates that the control of phytoplankton and the support of higher trophic levels involving copepods have clear potential to be adversely affected under future OA scenarios.

Continue reading ‘Ocean acidification affects the phyto-zoo plankton trophic transfer efficiency’

Effect of elevated CO2 concentration on microalgal communities in Antarctic pack ice

Increased anthropogenic CO2 emissions are causing changes to oceanic pH and CO2 concentrations that will impact many marine organisms, including microalgae. Phytoplankton taxa have shown mixed responses to these changes with some doing well while others have been adversely affected. Here, the photosynthetic response of sea-ice algal communities from Antarctic pack ice (brine and infiltration microbial communities) to a range of CO2 concentrations (400 ppm to 11,000 ppm in brine algae experiments, 400 ppm to 20,000 ppm in the infiltration ice algae experiment) was investigated. Incubations were conducted as part of the Sea-Ice Physics and Ecosystem Experiment II (SIPEX-2) voyage, in the austral spring (September–November), 2012. In the brine incubations, maximum quantum yield (Fv/Fm) and relative electron transfer rate (rETRmax) were highest at ambient and 0.049% (experiment 1) and 0.19% (experiment 2) CO2 concentrations, although, Fv/Fm was consistently between 0.53±0.10–0.68±0.01 across all treatments in both experiments. Highest rETRmax was exhibited by brine cultures exposed to ambient CO2 concentrations (60.15).

In a third experiment infiltration ice algal communities were allowed to melt into seawater modified to simulate the changed pH and CO2 concentrations of future springtime ice-edge conditions. Ambient and 0.1% CO2 treatments had the highest growth rates and Fv/Fm values but only the highest CO2 concentration produced a significantly lower rETRmax.

These experiments, conducted on natural Antarctic sea-ice algal communities, indicate a strong level of tolerance to elevated CO2 concentrations and suggest that these communities might not be adversely affected by predicted changes in CO2 concentration over the next century.

Continue reading ‘Effect of elevated CO2 concentration on microalgal communities in Antarctic pack ice’

Join “Pier-2-Peer” – the new GOA-ON mentorship initiative!

The Global Ocean Acidification Observing Network (GOA-ON;  http://www.goa-on.org/) is expanding its network of contributing countries and regions to achieve global coverage of OA observing capacity. As a global organization, GOA-ON relies on international collaboration to share data and understand the global ecological impacts of ocean acidification and is committed to promoting diversity across discipline, countries, socioeconomic status, gender and ethnicity. This year, the 3rd GOA-ON Science Workshop (8-10 May 2016) will have participation from over 40 countries and many new members from emerging regions are expected to attend.

To support the expansion of the observing network, GOA-ON is launching Pier-2-Peer, the new GOA-ON mentorship program, to match senior scientists with ocean acidification expertise with new GOA-ON members to support the development of OA monitoring (chemical to biological) in emerging regions. In the future, GOA-ON leadership hopes to secure financial support for travel and other training activities for mentors and mentees participating in GOA-ONs Pier-2- Peer mentoring program.

Continue reading ‘Join “Pier-2-Peer” – the new GOA-ON mentorship initiative!’

Carbon Capture and Storage (CCS): Risk assessment focused on marine bacteria

Carbon capture and storage (CCS) is one of the options to mitigate the negative effects of the climate change. However, this strategy may have associated some risks such as CO2 leakages due to an escape from the reservoir. In this context, marine bacteria have been underestimated. In order to figure out the gaps and the lack of knowledge, this work summarizes different studies related to the potential effects on the marine bacteria associated with an acidification caused by a CO2 leak from CSS. An improved integrated model for risk assessment is suggested as a tool based on the rapid responses of bacterial community. Moreover, this contribution proposes a strategy for laboratory protocols using Pseudomona stanieri (CECT7202) as a case of study and analyzes the response of the strain under different CO2 conditions. Results showed significant differences (p≤0.05) under six diluted enriched medium and differences about the days in the exponential growth phase. Dilution 1:10 (Marine Broth 2216 with seawater) was selected as an appropriate growth medium for CO2 toxicity test in batch cultures. This work provide an essential and a complete tool to understand and develop a management strategy to improve future works related to possible effects produced by potential CO2 leaks.

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Empirical algorithms to estimate water column pH in the Southern Ocean

Empirical algorithms are developed using high-quality GO-SHIP hydrographic measurements of commonly measured parameters (temperature, salinity, pressure, nitrate, and oxygen) that estimate pH in the Pacific sector of the Southern Ocean. The coefficients of determination, R2, are 0.98 for pH from nitrate (pHN) and 0.97 for pH from oxygen (pHOx) with RMS errors of 0.010 and 0.008, respectively. These algorithms are applied to Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) biogeochemical profiling floats, which include novel sensors (pH, nitrate, oxygen, fluorescence, and backscatter). These algorithms are used to estimate pH on floats with no pH sensors and to validate and adjust pH sensor data from floats with pH sensors. The adjusted float data provide, for the first time, seasonal cycles in surface pH on weekly resolution that range from 0.05 to 0.08 on weekly resolution for the Pacific sector of the Southern Ocean.

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OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book