Ocean acidification in the Global Calculator

The Global Calculator is a model of the world’s energy, land and food systems that allows users to explore the options for reducing global emissions to 2050, and to see the climate consequences of these choices to 2100. It is a free, interactive and open-source tool that helps you to understand the link between our lifestyle, the energy we use, and the consequences for our climate.

Ocean acidification is also included in this model. You can find it under the “Climate” section.

The Global Calculator takes the amount of extra greenhouse gas emitted by 2100 in the pathway the user has chosen and works out the temperature change and other climate impacts using the latest climate science from the Intergovernmental Panel on Climate Change (IPCC).

The Calculator is aimed at anyone interested in exploring what a low-carbon world could look like, but may particularly be of interest to people working in business, government, NGOs or university students. The Calculator has been funded by the UK Government’s International Climate Fund and the EU’s Climate-KIC, and has been built by an international team from many organisations.

Continue reading ‘Ocean acidification in the Global Calculator’

Carbonate chemistry in the northern South China Sea shelf-sea in June 2010

The distributions of dissolved inorganic carbon (CT), total alkalinity (AT) and pH at 25 °C (pH25) were determined in the northern South China Sea Shelf-sea (NoSoCS) in early June, 2010 during a low flow period. The distributions of the partial pressure of CO2 (pCO2), in situ pH, and temperature normalized pCO2 (NpCO2) were derived from the measured values. The distribution of AT is linearly related to salinity indicating that its distribution is controlled primarily by mixing between the surface water and the subsurface North Pacific Tropical Water. Aside from physical mixing, the distribution of CT is also influenced by its loss through biological uptake and CO2 evasion to the atmosphere. The net community production (NCP) rate in the NoSoCS is estimated to be 10±20 (with a range of 4–13) mmol C m−2 d−1. Within the NoSoCS, the NCP is elevated in the coastal upwelling area, where it is estimated to reach 30±17 mmol C m−2 d−1. In addition to temperature, upwelling and biological uptake also affect the distribution of the surface pCO2 and in situ pH.

The waters in the NoSoCS are super-saturated with respect to aragonite at all depths as the saturation horizon is at 600–800 m in the open northern South China Sea. Nevertheless, the aragonite saturation state, ΩAr, in the surface water, which is mostly between 3.3 and 3.5, is already within the range that has been suggested as barely adequate to marginal for the growth of the tropical shallow-water corals. The ΩAr is linearly related to in situ pH. At the reported rate of pH decrease in the oceans as a result of ocean acidification, ΩAr might reach a value that is considered “extremely marginal” within several decades and the existence of this type of coral reef ecosystem in the NoSoCS may then be threatened.

Continue reading ‘Carbonate chemistry in the northern South China Sea shelf-sea in June 2010′

The effects of water acidification, temperature and salinity on the regenerative capacity of the polychaete Diopatra neapolitana

Changes in seawater pH, temperature and salinity are expected to occur in the near future, which can be a threat to aquatic systems, mainly for marine coastal areas, and their inhabiting species. Hence, the present study proposes to evaluate the effects of temperature shifts, pH decrease and salinity changes in the tissue’s regenerative capacity of the polychaete Diopatra neapolitana. This study evidenced that D. neapolitana individuals exposed to lower pH exhibited a significantly lower capacity to regenerate their body, while with the increase of temperature individuals showed a higher capacity to regenerate their tissues. Furthermore, the present work demonstrated that individuals exposed to salinities 28 and 35 did not present significant differences between them, while salinities 21 and 42 negatively influenced the regenerative capacity of D. neapolitana. At the end of regeneration, comparing all conditions, high salinity (42) seemed to have a greater impact on the regenerative capacity of individuals than the other factors, since under this condition individuals took longer to completely regenerate. Overall, this study demonstrated that variations in abiotic factors can strongly affect D. neapolitana’s performance.

Continue reading ‘The effects of water acidification, temperature and salinity on the regenerative capacity of the polychaete Diopatra neapolitana’

The carbonate mineralogy and distribution of habitat-forming deep-sea corals in the southwest pacific region

Habitat-forming deep-sea scleractinian and alcyonacean corals from around the southwest Pacific were analysed for their calcium carbonate mineralogy. Scleractinian coral species Solenosmilia variabilis, Enallopsammia rostrata, Goniocorella dumosa, Madrepora oculata and Oculina virgosa were all found to be 100% aragonitic, while some members of the alcyonacean taxa Keratoisis spp., Lepidisis spp., and Paragorgia spp. were determined to be high magnesium (Mg) calcite (with 8–11 mol% MgCO3) and Primnoa sp. is bimineralic with both aragonite and Mg calcite. The majority of these habitat-forming deep-sea corals are found at intermediate depths (800–1200 m) in the Antarctic Intermediate Waters (AAIW) with low salinities (∼34.5), temperatures of 4–8 °C and high oxygen concentrations (>180 μmol/kg) and currently sitting above the aragonite saturation horizon (ASH). However, habitat-forming corals have been recorded from greater depths, in cooler waters (2–4 °C) that are undersaturated with respect to aragonite (Ωaragonite <1), but with oxygen levels still >160 μmol/kg. To address the sampling depth bias the coral records were normalised by the number of benthic stations (sampling effort) in the same depth range. This shows that the highest number of corals per sampling effort is between 1000–1400 m with corals present in over 5% of the stations at these depths. The normalised records and Boot Strap analyses suggests that scleractinian corals, especially S. variabilis should be present in >1% of stations down to 1800 m water depth, with E. rostrata, M. oculata and G. dumosa slightly shallower. While alcyonacean corals are found in >1% down to 2600 m, with Keratoisis spp. the deepest down to 2600 m, while Lepidisis spp. and Paragorgia spp. found down to 1800 m. This suggests that most species can probably tolerate some undersaturation of aragonite (Ωaragonite=0.8–0.9), with several species/genera (S. variabilis; Keratoisis spp.) even more tolerant of lower carbonate concentrations ([CO32−]), down to Ωaragonite of 0.7. With this tolerance for some carbonate undersaturation it is unclear how deep sea habitat-forming corals might respond to future ocean acidification. It is likely that some species/genera will cope better than others. However, future changes in oxygen concentrations and food availability, are also going to have a strong influence on the depth and spatial distribution of deep-sea corals in the southwest Pacific.

Continue reading ‘The carbonate mineralogy and distribution of habitat-forming deep-sea corals in the southwest pacific region’

Physiological responses and scope for growth upon medium-term exposure to the combined effects of ocean acidification and temperature in a subtidal scavenger Nassarius conoidalis

Physiological responses (ingestion rate, absorption rate and efficiency, respiration, rate, excretion rate) and scope for growth of a subtidal scavenging gastropod Nassarius conoidalis under the combined effects of ocean acidification (pCO2 levels: 380, 950, 1250 μatm) and temperature (15, 30°C) were investigated for 31 days. There was a significant reduction in all the physiological rates and scope for growth following short-term exposure (1 – 3 days) to elevated pCO2 except absorption efficiency at 15°C and 30°C, and respiration rate and excretion rate at 15°C. The percentage change in the physiological rates ranged from 0% to 90% at 15°C and from 0% to 73% at 30°C when pCO2 was increased from 380 μatm to 1250 μatm. The effect of pCO2 on the physiological rates was enhanced at high temperature for ingestion, absorption, respiration and excretion When the exposure period was extended to 31 days, the effect of pCO2 was significant on the ingestion rate only. All the physiological rates remained unchanged when temperature increased from 24°C to 30°C but the rates at 15°C were significantly lower, irrespective of the duration of exposure. Our data suggested that a medium-term exposure to ocean acidification has no effect on the energetics of N. conoidalis. Nevertheless, the situation may be complicated by a longer term of exposure and/or a reduction in salinity in a warming world.

Continue reading ‘Physiological responses and scope for growth upon medium-term exposure to the combined effects of ocean acidification and temperature in a subtidal scavenger Nassarius conoidalis’

Ocean acidification along the Gulf Coast and East Coast of the USA

As part of an effort to monitor changes in inorganic carbon chemistry of the coastal ocean, near-synoptic cruises are being conducted in the Northern Gulf of Mexico and along the East Coast of the United States. Here we describe observations obtained on a cruise in the summer of 2012 and compare them with results from a cruise following a similar track in 2007. The focus is on describing spatial patterns of aragonite saturation state (ΩAr). This parameter is an indicator of ecosystem health, in particular for calcifying organisms. The results show large-scale regional trends from different source waters at the northeastern and southwestern edges of the domain, along with the modulating effects of remineralization/respiration and riverine inputs. The broader patterns and changes over five years along the coast can be well described by the impacts of large-scale circulation, notably changes in source waters contributions. Changes in the well-buffered Loop Current and Gulf Stream with high ΩAr impact the waters in the southern part of the study area. The less buffered southward coastal currents with low ΩAr originating from the Labrador Sea and Gulf of St. Lawrence impact the ΩAr patterns in the Northern regions. The expected 2% average decrease in ΩAr in the surface mixed layer due to increasing atmospheric CO2 levels over the 5-year period is largely overshadowed by local and regional variability from changes in hydrography and mixed layer dynamics.

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The 8th New Zealand Ocean Acidification Workshop “Ocean Acidification in New Zealand: present state, pHuture directions”, 9-11 February, Dunedin, New Zealand 2015

The 8th NZOA workshop took place at the University of Otago, Dunedin, with 52 participants, 22 talks and a number of posters.

As with previous years there was a wide range of talks covering different aspects of OA. Invited international participants provided both workshops and talks, including a public lecture by Professor Gretchen Hofmann (University of California Santa Barbara), and plenary talks by Maria Byrne (Univ of Sydney) & Katharina Fabricius (AIMS, Townsville) that covered the use of vents as natural CO2 laboratories, multiple stressors, physiological and genetic changes and the potential for genetic evolution/adaptation.

An update was provided on the New Zealand Ocean Acidification Network (NZOAN), and following reports from the national Ocean Acidification Committees, these were then reformed into one organization, the New Zealand Ocean Acidification Community (NZOAC). Following the main workshop, an Ocean Acidification technical day took place at Portobello Marine Laboratory and included a series of workshops, both theoretical and practical, from invited speakers Peter Dillingham and Christina McGraw (U New England, Armidale) and Doug Mackie (University of Otago), covering statistic considerations of experiments and technical aspects of pH and carbonate system measurement.

Continue reading ‘The 8th New Zealand Ocean Acidification Workshop “Ocean Acidification in New Zealand: present state, pHuture directions”, 9-11 February, Dunedin, New Zealand 2015′

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