Archive for November, 2015

Acidification des océans : la menace invisible (text and videos; in French)

La menace est invisible. Pourtant c’est l’une des conséquences du réchauffement climatique, qui pourrait modifier en profondeur la biodiversité marine : l’acidification de la mer. Un phénomène déjà en marche même si en Bretagne, les effets ne se feraient sentir que vers 2080.

Chaque mois, les scientifiques de la station marine de Roscoff se rendent en rade de Brest pour réaliser des prélèvements. Prélèvements d’eau de mer pour mesurer sa température, sa salinité, son PH. Mais aussi prélèvements de maërl, une petite algue calcaire que l’on trouve au fond de la mer et qui à l’instar du corail, abrite une multitude d’animaux : le maërl leur sert un peu de garde-manger.

Continue reading ‘Acidification des océans : la menace invisible (text and videos; in French)’

Ocean acidification affects larval swimming in Ostrea lurida but not Crassostrea gigas

The effects of ocean acidification (OA), which results from increased CO2 emissions, are of particular concern for calcifying marine organisms. In marine invertebrates, the larval stages are generally considered the most vulnerable to the effects of OA and many recent studies show negative impacts of OA on early developmental stages of calcifying marine invertebrates. I studied the impact of OA on larval swimming performance and behavior in the Pacific oyster, Crassostrea gigas, and the Olympia oyster, Ostrea lurida. Swimming studies can be used to understand how short-term performance and behavior changes may affect the long-term success of populations. In this study, digital larval tracking was used to test for changes in swimming performance and behavior in larvae reared at pCO2 levels of 400, 800, and 1200 ppm. Experiments were run on hatchery-bred larvae from the beginning of the larval period to the pediveliger stage. Morphological and energetic changes were analyzed to determine if they corresponded to swimming performance and behavior differences between pCO2 treatments. Results showed few swimming performance changes in C. gigas larvae and no changes in swimming behavior, suggesting that transport will not be affected by OA in this species. However, C. gigas was affected morphologically and energetically by OA. O. lurida increased swimming speeds in response to increased pCO2 levels, but vertical displacement velocity did not change. O. lurida also increased helical pitch and energy allocated to swimming in response to OA, but did not show any morphological changes. Swimming performance and behavior changes observed in O. lurida suggest that OA could affect larval transport and connectivity in this species, ultimately affecting the success of later developmental stages.

Continue reading ‘Ocean acidification affects larval swimming in Ostrea lurida but not Crassostrea gigas’

Job vacancy: Research Associate / Research Fellow (Chemical And Palaeoceanography), University of Western Australia

Closing date for applications: Friday, 29 January 2016!

  • 3 year appointment
  • Minimum commencing salary for PhD is $88,520 p.a. or Level B $93,182 – $110,654 p.a.

The University of Western Australia (UWA) is ranked amongst the top Australian universities and a member of the prestigious Group of Eight research-intensive universities ranked among the top 100 universities in the world.

We invite a highly motivated post-doctoral researcher to undertake cutting-edge research in the area of chemical oceanography/palaeoceanography within the Centre, working under the general guidance of ARC Laureate Fellow Professor Malcolm McCulloch.

The Research Fellow will develop an innovative research program and foster research excellence within the ARC Centre in the area of coral reef studies that contributes to the general theme of the Centre: Responding to a Changing World. We are seeking a person with high-level expertise who can take a leading role in developing and utilising state-of-the-art in-situ laser ablation geochemical facilities to better understand how global warming and ocean acidification will impact both deep-sea and shallow water coral reef systems.

The research will address fundamental questions related to CO2 driven climate change and how the combined forces of global warming and ocean acidification will influence key processes underpinning coral reef resilience and bio-calcification generally. Topics of interest include coral calcification, bio-calcification systems as geochemical archives of climate change and the capacity of both shallow and deep-sea calcifying systems to adapt to rapidly changing environmental conditions.

Continue reading ‘Job vacancy: Research Associate / Research Fellow (Chemical And Palaeoceanography), University of Western Australia’

Climate change: Atlantic plankton bloom reflects soaring carbon dioxide levels, scientists say

Photo credit: Rex

Photo credit: Rex

Scientists say growth of coccolithophores, a microscopic marine alga, could be ‘canary in the coalmine’ for climate change.

A microscopic marine alga with a shell-like skeleton has increased more than tenfold in the North Atlantic over the past 50 years in response to rising levels of carbon dioxide, scientists have discovered.

The dramatic “bloom” of coccolithophores since the 1960s is unprecedented and marine biologists said they are both astonished and mystified by such a sharp increase in microscopic phytoplankton.

An analysis of more than 81,000 plankton samples collected over the past half century has found that the percentage of coccolithophores has increased from about 2 per cent to more than 20 per cent, with a dramatic acceleration occurring after the late 1990s.

Continue reading ‘Climate change: Atlantic plankton bloom reflects soaring carbon dioxide levels, scientists say’

Rapid plankton growth in ocean seen as sign of carbon dioxide loading

A microscopic marine alga is thriving in the North Atlantic to an extent that defies scientific predictions, suggesting swift environmental change as a result of increased carbon dioxide in the ocean, a study led a by Johns Hopkins University scientist has found.

What these findings mean remains to be seen, however, as does whether the rapid growth in the tiny plankton’s population is good or bad news for the planet.

Published Thursday in the journal Science, the study details a tenfold increase in the abundance of single-cell coccolithophores between 1965 and 2010, and a particularly sharp spike since the late 1990s in the population of these pale-shelled floating phytoplankton.

“Something strange is happening here, and it’s happening much more quickly than we thought it should,” said Anand Gnanadesikan, associate professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at Johns Hopkins and one of the study’s five authors.

Continue reading ‘Rapid plankton growth in ocean seen as sign of carbon dioxide loading’

Multidecadal increase in North Atlantic coccolithophores and the potential role of rising CO2

As anthropogenic CO2 emissions acidify the oceans, calcifiers generally are expected to be negatively affected. However, using data from the Continuous Plankton Recorder, we show that coccolithophore occurrence in the North Atlantic increased from ~2 to over 20% from 1965 through 2010. We used Random Forest models to examine >20 possible environmental drivers of this change, finding that CO2 and the Atlantic Multidecadal Oscillation were the best predictors, leading us to hypothesize that higher CO2 levels might be encouraging growth. A compilation of 41 independent laboratory studies supports our hypothesis. Our study shows a long-term basin-scale increase in coccolithophores and suggests that increasing CO2 and temperature have accelerated the growth of a phytoplankton group that is important for carbon cycling.

Continue reading ‘Multidecadal increase in North Atlantic coccolithophores and the potential role of rising CO2’

Two decades of inorganic carbon dynamics along the West Antarctic Peninsula (update)

We present 20 years of seawater inorganic carbon measurements collected along the western shelf and slope of the Antarctic Peninsula. Water column observations from summertime cruises and seasonal surface underway pCO2 measurements provide unique insights into the spatial, seasonal, and interannual variability in this dynamic system. Discrete measurements from depths > 2000 m align well with World Ocean Circulation Experiment observations across the time series and underline the consistency of the data set. Surface total alkalinity and dissolved inorganic carbon data showed large spatial gradients, with a concomitant wide range of Ωarag (< 1 up to 3.9). This spatial variability was mainly driven by increasing influence of biological productivity towards the southern end of the sampling grid and meltwater input along the coast towards the northern end. Large inorganic carbon drawdown through biological production in summer caused high near-shore Ωarag despite glacial and sea-ice meltwater input. In support of previous studies, we observed Redfield behavior of regional C / N nutrient utilization, while the C / P (80.5 ± 2.5) and N / P (11.7 ± 0.3) molar ratios were significantly lower than the Redfield elemental stoichiometric values. Seasonal salinity-based predictions of Ωarag suggest that surface waters remained mostly supersaturated with regard to aragonite throughout the study. However, more than 20 % of the predictions for winters and springs between 1999 and 2013 resulted in Ωarag < 1.2. Such low levels of Ωarag may have implications for important organisms such as pteropods. Even though we did not detect any statistically significant long-term trends, the combination of on\-going ocean acidification and freshwater input may soon induce more unfavorable conditions than the ecosystem experiences today.

Continue reading ‘Two decades of inorganic carbon dynamics along the West Antarctic Peninsula (update)’

An automated monitoring and control system for flow-through co-cycling hypoxia and pH experiments

Acidification research has exploded in recent years, however, experiments testing effects of co-cycling hypoxia and pH on ecological and physiological processes are rare, despite the pervasiveness and potential importance of co-varying fluctuations in these parameters. Co-cycling dissolved oxygen (DO) and pH are difficult to precisely control, as gases used for manipulation influence both parameters. We successfully developed a LabVIEW™-based system capable of monitoring and controlling co-varying DO and pH in raw seawater flow-through aquaria. Using feedback from Oxyguard DO probes and Honeywell ion sensitive field effect transistor Durafet pH sensors, our system controls ratios of nitrogen, oxygen, carbon dioxide, atmospheric air, and CO2-stripped air within a total gas flow rate through mass flow controllers, to achieve target co-cycling DO and pH values in five treatments. Our system performed well in two long-term experiments investigating effects of diel-cycling hypoxia and pH on eastern oyster (Crassostrea virginica) feeding, growth, fecundity, Perkinsus sp. (Dermo) infection dynamics and immune response. In our 2013 adult oyster experiment, the severe low DO treatment averaged only 0.04 mg L−1 higher than the 0.50 mg L−1 target, and the moderate hypoxia averaged only 0.05 mg L−1 higher than the 1.30 mg L−1 target over 48 d of cycles. Mean pH for the hypercapnia plateau was within 0.02 above the 7.00 target. In our 2013 spat experiment, daily minimum DO in the severe and moderate hypoxia treatments were both within 0.06 mg L−1 of the 0.50 and 1.3 mg L−1 targets, respectively; hypercapnia plateau pH values were within 0.01 of our 7.00 target.

Continue reading ‘An automated monitoring and control system for flow-through co-cycling hypoxia and pH experiments’

CO2 Modeller brings climate change and emissions targets within touching distance

Scientists and computer engineers at the University of Southampton have developed an interactive climate app – CO2 Modeller – which can fit in your pocket and help you to gauge the future effects of carbon emissions around key sensitivities of the Earth’s climate.

The new app, CO2 Modeller, provides an interactive tool to allow anyone – from members of the public to policy makers – to explore for themselves the implications of delaying emission reductions on their tablet or smartphone.

Using an easy-to-follow touchscreen, users of the app can review how carbon emission targets and outcomes will impact four key areas of climate change – future global warming, sea level rise, ocean acidification and CO2 concentration – over the next 85 years.

The app’s developers, from Ocean and Earth Science and Electronics and Computing Science, at the University of Southampton, believe that making climate modelling tools so accessible in this way will help us gain a greater understanding of the carbon emission targets and reduction policies proposed at international policy forums, such as the forthcoming COP21 Paris climate talks.

Continue reading ‘CO2 Modeller brings climate change and emissions targets within touching distance’

OA-ICC technical meeting on the management of biological response to ocean acidification data, 17-18 November 2015, Monaco

The IAEA Ocean Acidification International Coordination Centre (OA-ICC) organized a technical meeting on the management of biological response data related to ocean acidification, focusing specifically on the discovery and access of these data via a common data portal. The meeting was hosted at the IAEA Environment Laboratories in Monaco, November 17 – 18, 2015 and was a follow-up to two previous meetings held at the facility:

The meeting brought together scientific and technical experts actively involved in the dissemination or use of ocean acidification data via web based portals, and technical experts providing similar technical capabilities in support of other areas of research.

The objectives of the meeting were to:
1. Provide updates on metadata and portal activities from:
a. 2014 workshop: “Technical meeting on management of biological data related to ocean acidification: international cooperation and development of standards”
b. 2015 workshop: “Technical meeting: Towards a GOA-ON data portal”
2. Finalize the direction for addressing ocean acidification portal needs with a specific focus on biological effects data
3. Develop a plan and establish commitments for completing the portal activity

The meeting provided an opportunity for researchers to communicate the vision for what a common portal should provide, a one-stop shop for the discovery and harmonized access to ocean acidification data.

Continue reading ‘OA-ICC technical meeting on the management of biological response to ocean acidification data, 17-18 November 2015, Monaco’

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Ocean acidification in the IPCC AR5 WG II

OUP book