Physiological responses of gray mullet Mugil cephalus to low-pH water

We examined changes in the physiological responses of gray mullet Mugil cephalus exposed to acidic seawater (pH 6.0, 6.5, 7.0) and normal seawater (pH 8.0, control) for 15 days. As pH decreased, survival rate and body weight also decreased. Levels of aminotransferase, total protein and triglycerides also differed significantly with changes in pH, presumably due to stress caused by exposure to acidic water. The level of osmotic pressure was significantly higher in the pH 6.0 group than in other groups. Superoxide dismutase was significantly higher in the pH 6.5 and 7.0 groups than in the pH 8.0 group, and glutathione level was lowest in the pH 6.0 group. We conclude that decreasing the pH level of seawater induces a stress response in fish, damaging their ability to control their hematological and osmotic pressure. Antioxidant enzymes are generally sensitive to osmotic stress; in this study, antioxidant activity significantly changed with pH level. These results indicate that physiological stress induced by exposure to acidification reduces survival rates and inhibits growth in M. cephalus.

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Release of Version 5 of the Surface Ocean CO2 Atlas – celebrating 10 years of SOCAT!

On behalf of the Surface Ocean CO2 Atlas (SOCAT) scientific community, we are proud to announce the release of SOCAT Version 5! SOCAT is a synthesis activity by the international marine carbon research community (>100 contributors). SOCAT version 5 has 21.5 million quality-controlled, surface ocean fCO2 (fugacity of carbon dioxide) observations from 1957 to January 2017 for the global oceans and coastal seas. Calibrated sensor data are also available. Automation allows annual, public releases of SOCAT. The SOCAT data is discoverable, accessible and citable. SOCAT enables quantification of the ocean carbon sink and ocean acidification and evaluation of ocean biogeochemical models. Celebrating its 10th anniversary in 2017, SOCAT represents a milestone in biogeochemical and climate research, and in informing policy.

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Scales and drivers of seasonal pCO2 dynamics and net ecosystem exchange along the coastal waters of southeastern Arabian Sea

The impact of seasonal coastal upwelling on the dynamics of dissolved inorganic carbon (DIC) and sea-air fluxes of CO2 along the coastal waters of Kochi was investigated during 2015, as a part of Ecosystem Modelling Project. The surface water pCO2 varied from 396 to 630 μatm during the study period. Significant inter-seasonal variations were found in the distribution of physico-chemical variables and surface pCO2. An increase of 102.1 μatm of pCO2 was noticed over a two-decade period with a rate of 5.3 μatm y− 1. There was an agreement between the fluxes of CO2 and net ecosystem production (NEP) with respect to the trophic status while NEP was higher than CO2 fluxes by a factor of 3.9. The annual net ecosystem exchange (NEE) was estimated to be 15.02 mmol C m− 2 d− 1 indicating that the coastal waters of Kochi are highly heterotrophic in nature.

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Combined effects of elevated pCO2 and warming facilitate Cyanophage infections

Elevated pCO2 and warming are generally expected to influence cyanobacterial growth, and may promote the formation of blooms. Yet, both climate change factors may also influence cyanobacterial mortality by favoring pathogens, such as viruses, which will depend on the ability of the host to adapt. To test this hypothesis, we grew Plectonema boryanum IU597 under two temperature (25 and 29°C) and two pCO2 (400 and 800 μatm) conditions for 1 year, after which all treatments were re-exposed to control conditions for a period of 3 weeks. At several time points during the 1 year period, and upon re-exposure, we measured various infection characteristics of it associated cyanophage PP, including the burst size, latent period, lytic cycle and the efficiency of plaquing (EOP). As expected, elevated pCO2 promoted growth of P. boryanumequally over the 1 year period, but warming did not. Burst size increased in the warm treatment, but decreased in both the elevated pCO2 and combined treatment. The latent period and lytic cycle both became shorter in the elevated pCO2 and higher temperature treatment, and were further reduced by the combined effect of both factors. Efficiency of plaquing (EOP) decreased in the elevated pCO2 treatment, increased in the warm treatment, and increased even stronger in the combined treatment. These findings indicate that elevated pCO2 enhanced the effect of warming, thereby further promoting the virus infection rate. The re-exposure experiments demonstrate adaptation of the host leading to higher biomass build-up with elevated pCO2 over the experimental period, and lower performance upon re-exposure to control conditions. Similarly, virus burst size and EOP increased when given warm adapted host, but were lower as compared to the control when the host was re-exposed to control conditions. Our results demonstrate that adaptation but particularly physiological acclimation to climate change conditions favored viral infections, while limited host plasticity and slow adaptation after re-exposure to control conditions impeded host biomass build-up and viral infections.

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Combined effects of sea water acidification and copper exposure on the symbiont-bearing foraminifer Amphistegina gibbosa

Coral reefs are threatened by global and local stressors such as ocean acidification and trace metal contamination. Reliable early warning monitoring tools are needed to assess and monitor coral reef health. Symbiont-bearing foraminifers (Amphistegina gibbosa) were kept under ambient conditions (no sea water acidification and no copper addition) or exposed to combinations of different levels of sea water pH (8.1, 7.8, 7.5 and 7.2) and environmentally relevant concentrations of dissolved copper (measured: 1.0, 1.6, 2.3 and 3.2 µg L−1) in a mesocosm system. After 10- and 25-d exposure, foraminifers were analyzed for holobiont Ca2+-ATPase activity, bleaching, growth and mortality. Enzyme activity was inhibited in foraminifers exposed to pH 7.2 and 3.2 µg L−1 Cu for 25 d. Bleaching frequency was also higher at pH 7.2 combined with copper addition. There was no significant effect of sea water acidification and copper addition on mortality. However, test size was smaller in foraminifers exposed to copper, with a positive interactive effect of sea water acidification. These findings can be explained by the higher availability of free copper ions at lower water pH. This condition would increase Cu competition with Ca2+ for the binding sites on the organism, thus inhibiting Ca2+-ATPase activity and affecting the organism’s overall fitness. Findings reported here suggest that key processes in A. gibbosa, such as calcification and photosynthesis, are affected by the combined effect of global (sea water acidification) and local (copper contamination) stressors. Considering the experimental conditions employed (mesocosm system, possible ocean acidification scenarios, low copper concentrations, biomarkers of ecological relevance and chronic exposure), our findings support the use of foraminifera and biomarkers analyzed in the present study as reliable tools to detect and monitor the ecological impacts of multiple stressors in coral reef environments.

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Herrera, Kilmer team up on ocean acidification issue

WASHINGTON, D.C. — Two U.S. representatives from Washington state, Derek Kilmer and Jaime Herrera Beutler, have reintroduced bipartisan legislation to help fight ocean acidification. The bill, entitled the Ocean Acidification Innovation Act (H.R. 2882), would allow federal agencies to use existing funds to design prize competitions in order to bolster efforts to manage, research, and monitor ocean acidification and its impacts.

According to a press release, the “budget-neutral” legislation was created in collaboration with the X PRIZE Foundation, a non-profit that creates public competitions, with the goal of getting people and businesses more invested in finding solutions to problems that affect society at large. For example, in 2004, the organization gave an award for efforts to develop personal space flights. The industry has since grown, generating more than $1 billion in investments.

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The rise of CO2 and ocean acidification

Ocean acidification is a closely linked consequence of increasing carbon dioxide (CO2) in the atmosphere, involving multiple changes in seawater chemistry. Observed long-term trends are superimposed on natural variability over a range of space and time scales. The future scale and impacts of ocean acidification depend on how rapidly CO2emissions can be reduced. Although the chemistry of ocean acidification is relatively well understood, effects on marine life, and subsequent socio-economic consequences, remain uncertain. The main biological knowledge gaps relate to genetic adaptation potential, interactions with other stressors (that may also be linked to climate change), and complex ecological interactions associated with competition, species interdependencies, and food webs. Societal impacts are likely to be greatest for human communities that are most reliant directly on marine bioresources, predominantly in coastal areas and small island states.

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Ocean acidification in the IPCC AR5 WG II

OUP book