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AGU session on ocean acidification: Marine-based management of atmospheric carbon dioxide and ocean acidification

The AGU Fall Meeting will be held on 9-13 December 2019 in San Francisco, CA. The meeting will include a session on ocean acidification titled “Marine-based management of atmospheric carbon dioxide and ocean acidification”.

Session description: Ocean biology, chemistry and physics play a central role in naturally controlling oceanic/atmospheric CO2 levels. To avoid major global climate impacts and ocean acidification, reducing CO2 emissions is no longer sufficient; CO2 removal from the ocean/atmosphere system is now also required. This session will explore ways of restoring, enhancing, and augmenting naturally-occurring marine processes for regulating oceanic and atmospheric CO2 and ocean acidity levels. Specific examples include, but are not limited to: Blue Carbon, macrophyte introduction, aquaculture, permaculture, nutrient enrichment, marine BECCS, enhanced weathering, alkalinity addition, enhanced upwelling/downwelling, and chemical or physical seawater CO2 stripping, conducted at local to global scales. In addition to technical aspects, presentations on the economic, regulatory, policy, geopolitical, governance, legal and ethical implications of the preceding are also invited.

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Robustness of Adamussium colbecki shell to ocean acidification in a short-term exposure


• Adamussium colbecki shell crystals deposition is not affected by low pH exposure.

• A. colbecki shell resulted robust to low pH exposure in terms of micro and nano-mechanics.

• Larger resilience of Antarctic communities to predation than foreseen in a Global Change scenario.


Atmospheric pCO2 has increased since the industrial revolution leading to a lowering of the ocean surface water pH, a phenomenon called ocean acidification (OA). OA is claimed to be a major threat for marine organisms and ecosystems and, particularly, for Polar regions. We explored the impact of OA on the shell mechanical properties of the Antarctic scallop Adamussium colbecki exposed for one month to acidified (pH 7.6) and natural conditions (unmanipulated littoral water), by performing Scanning Electron Microscopy, nanoindentation and Vickers indentation on the scallop shell. No effect of pH could be detected either in crystal deposition or in the mechanical properties. A. colbecki shell was found to be resistant to OA, which suggests this species to be able to face a climate change scenario that may threat the persistence of the endemic Antarctic species. Further investigation should be carried out in order to elucidate the destiny of this key species in light of global change.

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An enhanced ocean acidification observing network: from people to technology to data synthesis and information exchange

A successful integrated ocean acidification (OA) observing network must include (1) scientists and technicians from a range of disciplines from physics to chemistry to biology to technology development; (2) government, private, and intergovernmental support; (3) regional cohorts working together on regionally specific issues; (4) publicly accessible data from the open ocean to coastal to estuarine systems; (5) close integration with other networks focusing on related measurements or issues including the social and economic consequences of OA; and (6) observation-based informational products useful for decision making such as management of fisheries and aquaculture. The Global Ocean Acidification Observing Network (GOA-ON), a key player in this vision, seeks to expand and enhance geographic extent and availability of coastal and open ocean observing data to ultimately inform adaptive measures and policy action, especially in support of the United Nations 2030 Agenda for Sustainable Development. GOA-ON works to empower and support regional collaborative networks such as the Latin American Ocean Acidification Network, supports new scientists entering the field with training, mentorship, and equipment, refines approaches for tracking biological impacts, and stimulates development of lower-cost methodology and technologies allowing for wider participation of scientists. GOA-ON seeks to collaborate with and complement work done by other observing networks such as those focused on carbon flux into the ocean, tracking of carbon and oxygen in the ocean, observing biological diversity, and determining short- and long-term variability in these and other ocean parameters through space and time.

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Ocean acidification affects calcareous tube growth in adult stage and reared offspring of serpulid polychaetes

The energetically costly transition from free-swimming larvae to benthic life stage and maintenance of a calcareous structure can make calcifying marine invertebrates vulnerable to ocean acidification. The first goal of this study was to evaluate the impacts of ocean acidification on calcified tube growth for two Serpulidae polychaete worms. Spirorbis sp. and Spirobranchus triqueter were collected at 11 m depth from the Northwest Mediterranean Sea and maintained for 30 and 90 d, at three mean pHT levels (total scale) of 8.1 (ambient), 7.7, and 7.4. Moderately decreased tube elongation rates were observed in both species at a pHT of 7.7 while severe reductions occurred at pHT 7.4. There was visual evidence of dissolution and tubes were more fragile at lower pH but, fragility was not attributed to changes in fracture toughness. Instead, it appeared to be due to the presence of larger alveoli covered in a thinner calcareous layer. The second objective of the study was to test for effects in offspring development of the species S. triqueter. Spawning was induced, and offspring were reared in the same pH conditions the parents experienced. Trochophore size was reduced at the lowest pH level but settlement success was similar across pH conditions. Post-settlement tube growth was most affected. At 38 d post-settlement, juvenile tubes at pHT of 7.7 and 7.4 were half the size of those at pHT 8.1. Results suggest future carbonate chemistry will negatively affect initiation and persistence of both biofouling and epiphytic polychaete tube worms.

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Climate change and carbon dioxide may help squid thrive

While the world is thinking about ways to fight ocean acidification and reduce the concentration of carbon-dioxide in the atmosphere to fight climate change, some marine animals may be able to survive even under the most cruel conditions in the ocean. That said, a new study has found that even in the worst-case ocean acidification scenario, carbon dioxide could actually help squid thrive.

According to new research conducted by Dr Blake Spady at the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University, the squid live on the edge of their environmental oxygen limitations because of their swimming technique that demands a lot of energy. Because of this, scientists expected that they would have a lot of difficulties surviving in this scenario, as the carbon dioxide concentrations continue to grow in the ocean water.

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Impact of climate change on the American lobster (Homarus americanus): Physiological responses to combined exposure of elevated temperature and pCO2

• Climate Change (2300 scenario) has a significant impact on the acid-base status in H. americanus.

• Climate Change causes retention of ammonia in hemolymph.

• Under Climate Change conditions hemolymph pCO2 does NOT exceed environmental pCO2.

• Climate Change causes increase in MO2 and ammonia excretion.

• Climate Change causes decrease in citrate synthase in tail muscle.

The physiological consequences of exposing marine organisms to predicted future ocean scenarios, i.e. simultaneous increase in temperature and pCO2, have only recently begun to be investigated. Adult American lobster (Homarus americanus) were exposed to either current (16 °C, 47 Pa pCO2, pH 8.10) or predicted year 2300 (20 °C, 948 Pa pCO2, pH 7.10) ocean parameters for 14–16 days prior to assessing physiological changes in their hemolymph parameters as well as whole animal ammonia excretion and resting metabolic rate. Acclimation of lobster simultaneously to elevated pCO2 and temperature induced a prolonged respiratory acidosis that was only partially compensated for via accumulation of extracellular HCO3– and ammonia. Furthermore, acclimated animals possessed significantly higher ammonia excretion and oxygen consumption rates suggesting that future ocean scenarios may increase basal energetic demands on H. americanus. Enzyme activity related to protein metabolism (glutamine dehydrogenase, alanine aminotransferase, and aspartate aminotransferase) in hepatopancreas and muscle tissue were unaltered in future ocean scenario exposed animals; however, muscular citrate synthase activity was reduced suggesting that, while protein catabolism may be unchanged, the net energetic output of muscle may be compromised in future scenarios. Overall, H. americanus acclimated to ocean conditions predicted for the year 2300 appear to be incapable of fully compensating against climate change-related acid-base challenges and experience an increase in metabolic waste excretion and oxygen consumption. Combining our study with past literature on H. americanus suggests that the whole lifecycle from larvae to adult stages is at risk of severe growth, survival and reproductive consequences due to climate change.

Continue reading ‘Impact of climate change on the American lobster (Homarus americanus): Physiological responses to combined exposure of elevated temperature and pCO2’

Effects of ocean acidification on marine photosynthetic organisms under the concurrent influences of warming, UV radiation, and deoxygenation

The oceans take up over 1 million tons of anthropogenic CO2 per hour, increasing dissolved pCO2 and decreasing seawater pH in a process called ocean acidification (OA). At the same time greenhouse warming of the surface ocean results in enhanced stratification and shoaling of upper mixed layers, exposing photosynthetic organisms dwelling there to increased visible and UV radiation as well as to a decreased nutrient supply. In addition, ocean warming and anthropogenic eutrophication reduce the concentration of dissolved O2 in seawater, contributing to the spread of hypoxic zones. All of these global changes interact to affect marine primary producers. Such interactions have been documented, but to a much smaller extent compared to the responses to each single driver. The combined effects could be synergistic, neutral, or antagonistic depending on species or the physiological processes involved as well as experimental setups. For most calcifying algae, the combined impacts of acidification, solar UV, and/or elevated temperature clearly reduce their calcification; for diatoms, elevated CO2 and light levels interact to enhance their growth at low levels of sunlight but inhibit it at high levels. For most photosynthetic nitrogen fixers (diazotrophs), acidification associated with elevated CO2 may enhance their N2 fixation activity, but interactions with other environmental variables such as trace metal availability may neutralize or even reverse these effects. Macroalgae, on the other hand, either as juveniles or adults, appear to benefit from elevated CO2 with enhanced growth rates and tolerance to lowered pH. There has been little documentation of deoxygenation effects on primary producers, although theoretically elevated CO2 and decreased O2 concentrations could selectively enhance carboxylation over oxygenation catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase and thereby benefit autotrophs. Overall, most ocean-based global change biology studies have used single and/or double stressors in laboratory tests. This overview examines the combined effects of OA with other features such as warming, solar UV radiation, and deoxygenation, focusing on primary producers.

Continue reading ‘Effects of ocean acidification on marine photosynthetic organisms under the concurrent influences of warming, UV radiation, and deoxygenation’

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Ocean acidification in the IPCC AR5 WG II

OUP book