Archive for March, 2011

Le CO2 : poison pour les poissons (radio; in French)

Le changement climatique et l’acidification des océans ont un impact sur la survie des poissons. C’est le résultat d’une étude australienne qui vient de paraître.

L’océan piège une partie du gaz carbonique que nous émettons chaque année. Depuis la révolution industrielle il a stocké un tiers des émissions de CO2. Mais la concentration provoque une diminution du PH de l’eau de mer. Les océans se sont acidifiés de 30% en un siècle. Les chercheurs australiens ont tenté une expérience avec le fameux poisson clown. ILS ont plongé des larves dans deux bassins : l’un avec une concentration normale de CO2. L’autre avec les niveaux que l’on pourrait atteindre à la fin du siècle. Dans chacun des bassins, ils ont fait passer un courant d’eau porteur de l’odeur d’un prédateur. Ils se sont rendu compte que les poissons qui barbotent dans de l’eau acide restaient insouciants à cette odeur et passent 93% de leur temps dans le courant. Ils prennent plus de risque et leur taux de mortalité est entre 5 à 9 fois plus important. Alors que les autres, évitent le courant dangereux. Voilà pour l’observation. Quant aux explications, elles sont encore théoriques.

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Ocean acidification – changing planet (video)

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Tipping Point (movie)

Tipping Point“, the new documentary on ocean acidification will be show twice at the meeting of the European Geosciences Union next week (room GeoCinema):

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Letter: Ocean acidification is just hype

To find an example of a propagandist “scientist” using bogus science and emotional language against human progress and our industrial infrastructure, look no further than the Clark College biology department’s Rebecca Martin. Her March 20 Local View, “We can help combat ocean acidification,” revealed a common theme in media, that the ends justify the means in social engineering — in this case “ocean acidification.”

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PhD studentship the implications of ocean acidification in combination with chemical stressors for juvenile fish

The Centre for Environment, Fisheries and Aquaculture Science (Cefas) and University of Exeter are offering a 3 year funded doctoral studentship to commence 1st October 2011: tuition fees (UK/EU rate only) and annual stipend of 13,590 pa.

Supervisory team: Dr Rod Wilson and Professor Charles Tyler (Exeter) plus Professor Tom Hutchinson, Dr Matthew Sanders and Dr Will Le Quesne (Cefas)

Location: University of Exeter, Streatham Campus, Exeter and Cefas, Weymouth

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Early development and molecular plasticity in the Mediterranean sea urchin Paracentrotus lividus exposed to CO2-driven acidification

Ocean acidification is predicted to have significant effects on benthic calcifying invertebrates, in particular on their early developmental stages. Echinoderm larvae could be particularly vulnerable to decreased pH, with major consequences for adult populations. The objective of this study was to understand how ocean acidification would affect the initial life stages of the sea urchin Paracentrotus lividus, a common species that is widely distributed in the Mediterranean Sea and the NE Atlantic. The effects of decreased pH (elevated PCO2) were investigated through physiological and molecular analyses on both embryonic and larval stages. Eggs and larvae were reared in Mediterranean seawater at six pH levels, i.e. pHT 8.1, 7.9, 7.7, 7.5, 7.25 and 7.0. Fertilization success, survival, growth and calcification rates were monitored over a 3 day period. The expression of genes coding for key proteins involved in development and biomineralization was also monitored. Paracentrotus lividus appears to be extremely resistant to low pH, with no effect on fertilization success or larval survival. Larval growth was slowed when exposed to low pH but with no direct impact on relative larval morphology or calcification down to pHT 7.25. Consequently, at a given time, larvae exposed to low pH were present at a normal but delayed larval stage. More surprisingly, candidate genes involved in development and biomineralization were upregulated by factors of up to 26 at low pH. Our results revealed plasticity at the gene expression level that allows a normal, but delayed, development under low pH conditions.
Continue reading ‘Early development and molecular plasticity in the Mediterranean sea urchin Paracentrotus lividus exposed to CO2-driven acidification’

Land-sea carbon and cutrient fluxes and coastal ocean CO2 exchange and acidification: Past, present, and future

Epochs of changing atmospheric CO2 and seawater CO2-carbonic acid system chemistry and acidification have occurred during the Phanerozoic at various time scales. On the longer geologic time scale, as sea level rose and fell and continental free board decreased and increased, respectively, the riverine fluxes of Ca, Mg, DIC, and total alkalinity to the coastal ocean varied and helped regulate the C chemistry of seawater, but nevertheless there were major epochs of ocean acidification (OA). On the shorter glacial-interglacial time scale from the Last Glacial Maximum (LGM) to late preindustrial time, riverine fluxes of DIC, total alkalinity, and N and P nutrients increased and along with rising sea level, atmospheric PCO2 and temperature led, among other changes, to a slightly deceasing pH of coastal and open ocean waters, and to increasing net ecosystem calcification and decreasing net heterotrophy in coastal ocean waters. From late the preindustrial time to the present and projected into the 21st century, human activities, such as fossil fuel and land use emissions of CO2 to the atmosphere, increasing application of N and P nutrient subsidies and combustion N to the landscape, and sewage discharges of C, N, P have led, and will continue to lead, to significant modifications of coastal ocean waters. The changes include a rapid decline in pH and carbonate saturation state (modern problem of ocean acidification), a shift toward dissolution of carbonate substrates exceeding production, potentially leading to the “demise” of the coral reefs, reversal of the direction of the sea to air flux of CO2 and enhanced biological production and burial of organic C, a small sink of anthropogenic CO2, accompanied by a continuous trend toward increasing autotrophy in coastal waters.
Continue reading ‘Land-sea carbon and cutrient fluxes and coastal ocean CO2 exchange and acidification: Past, present, and future’

Ocean acidification during the Cenozoic

The oceanic uptake of anthropogenic CO2 causes a progressive decrease of seawater-pH, a phenomenon that has been termed ‘ocean acidification’. Such are duction in pH and associated carbonate system changes is of concern because it may affect ocean biogeochemical processes such as biological calcification. The geological record provides a unique opportunity to study climate effects and the long-term response of marine organisms and ecosystems to variations in the Earth’s carbon cycle, and in particular the Paleocene/Eocene Thermal Maximum (PETM,~55 Ma) bears evidence for rapid C injection that may allow comparison with anthropogenic ocean acidification.
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Sentinel at Sea

UNH ocean scientists are in the vanguard of NOAA’s efforts to monitor ocean acidification remotely around the clock

For the past five years, a sentinel buoy has bobbed about in waters northeast of Appledore Island in the Gulf of Maine taking hourly readings of both atmospheric and oceanic CO2. It is one of just half a dozen such buoys nationwide making a crucial measurement to help scientists know how much carbon the ocean is taking up globally as atmospheric CO2 levels continue to rise.

More specifically, the Gulf of Maine buoy measurements are aimed at better understanding the role complex coastal waters play in the increasing acidification of the global ocean.

“We’re trying to understand how much carbon the ocean is taking up globally,” says research associate professor Doug Vandemark of the Ocean Process Analysis Laboratory and principal investigator on the CO2 buoy. He adds, “And one of the big questions is, If we don’t make measurements along our coasts, are we missing a big part of the picture?”
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CO2 killing our coral reefs, say experts

The world’s coral reefs are in danger of dying out in the next 20 years unless carbon emissions are cut drastically, warns a coalition of scientists led by Sir David Attenborough.

The delicate ecosystems, known as the “rainforests of the sea”, support huge amounts of marine life. But as oceans absorb CO2 they become more acidic, making it impossible for structures such as the Great Barrier Reef in Australia to survive.

Reefs are also at greater danger of bleaching as sea temperatures warm. Scientists gathered at the Royal Society in London to call for tougher target cuts in emissions. Sir David, who co-chaired the meeting, said the collapse of coral reefs meant the death of marine ecosystems. “We must do all that is necessary to protect the key components of the life of our planet as the consequences of decisions made now will likely be forever as far as humanity is concerned,” he said. Open water absorbs around a third of the CO2 in the air. At present, the concentration of CO2 in the atmosphere is 387 parts per million (ppm).

Alex Rogers, the scientific director of the International Programme on the State of the Oceans, says the figure will reach 450ppm in the next 20 years if the world continues to burn fossil fuels at the present rate, and once that figure was reached the ocean would become too acidic for coral to survive. “The kitchen is on fire and it’s spreading round the house. If we act quickly and decisively we may be able to put it out before the damage becomes irreversible,” he said.
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