Archive for April, 2012



Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica

Ocean acidification, caused by elevated seawater carbon dioxide levels, may have a deleterious impact on energetic processes in animals. Here we show that high PCO2 can suppress metabolism, measured as oxygen consumption, in the pteropod, L. helicina forma antarctica, by ~20%. The rates measured at 180–380 µatm (MO2 = 1.25 M−0.25, p = 0.007) were significantly higher (ANCOVA, p = 0.004) than those measured at elevated target CO2 levels in 2007 (789–1000 µatm, = 0.78 M−0.32, p = 0.0008;). However, we further demonstrate metabolic plasticity in response to regional phytoplankton concentration and that the response to CO2 is dependent on the baseline level of metabolism. We hypothesize that reduced regional Chl a levels in 2008 suppressed metabolism and masked the effect of ocean acidification. This effect of food limitation was not, we postulate, merely a result of gut clearance and specific dynamic action, but rather represents a sustained metabolic response to regional conditions. Thus, pteropod populations may be compromised by climate change, both directly via CO2-induced metabolic suppression, and indirectly via quantitative and qualitative changes to the phytoplankton community. Without the context provided by long-term observations (four seasons) and a multi-faceted laboratory analysis of the parameters affecting energetics, the complex response of polar pteropods to ocean acidification may be masked or misinterpreted.

Continue reading ‘Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica’

L’acidification des océans nuit à la production des huîtres (in French)

Une étude menée dans le Pacifique établit pour la première fois en milieu naturel le lien entre acidification et mortalité des naissains.

On connaissait les expériences menées en laboratoire, mais c’est la première fois que des chercheurs réussissent à montrer en milieu naturel l’effet néfaste de l’acidification des océans sur les huîtres. C’est ce que révèle une étude publiée dans la revue Limnology and Oceanography.

L’alerte remonte à 2007. Dans une des grandes écloseries d’huîtres de l’Oregon (États-Unis), fournissant les ostréiculteurs de la côte du Pacifique, les naissains ont commencé à dépérir. Les millions de bébés huîtres Crassostrea gigas, une fois plongés dans la mer, mouraient les uns après les autres. Une perte économique se comptant en millions de dollars.

Continue reading ‘L’acidification des océans nuit à la production des huîtres (in French)’

Acidification in Arabian Gulf – Insights from pH and temperature measurements

The detrimental effects of increasing atmospheric levels of carbon dioxide (CO2) and other greenhouse gases since the industrial revolution has led to a concerted international effort to control their release and abate the environmental and human health impacts. CO2 is removed from the atmosphere by photosynthesis of plants in the terrestrial environment and by aquatic sequestration. In the Middle East and other arid countries, terrestrial removal is minimal. The most likely removal pathway for CO2 in arid regions around the world is by aquatic sequestration. In the Middle East the major sink is the Arabian Gulf which leads to acidification of the marine environment. Biweekly pH concentration measurements in surface waters of the northern Arabian Gulf over a four year period in this study suggest that the Arabian Gulf waters are becoming increasingly acidic with time. Supporting evidence for increased CO2 sequestration comes from increased marine primary productivity over the past decade. Biological effects, such as coral bleaching, observed during this period suggest that urgent action is required to reverse the trend and protect marine life. The data highlight the fact that this semi-enclosed sea is undergoing a rapid degradation which may affect the oceanic chemistry and biogeochemical cycle much earlier than predicted for most oceanic waters.

Continue reading ‘Acidification in Arabian Gulf – Insights from pH and temperature measurements’

Nuevas tecnologías para el seguimiento de la acidificación marina en el espacio natural Costa del Garraf (in Spanish)

El proyecto propuesto desarrollará sistemas específicos para la medición de pH marino y CO2 atmosférico en la Costa del Garraf.

El aumento del contenido de CO2 en la atmósfera debido a las actividades antrópicas está provocando, a través del efecto invernadero y debido a que buena parte del CO2 emitido está siendo absorbido por los mares y océanos, una progresiva acidificación de sus aguas, lo cual tiene efectos devastadores para muchos organismos marinos.

Los sistemas de medición del pH marino y el CO2 atmosférico se implementarán en el observatorio OBSEA que, por sus características únicas, es especialmente idóneo para la toma de medidas en continuo a altas frecuencias de los diferentes parámetros de interés de una forma integrada.

Continue reading ‘Nuevas tecnologías para el seguimiento de la acidificación marina en el espacio natural Costa del Garraf (in Spanish)’

Ocean acidification induces multi-generational decline in copepod naupliar production with possible conflict for reproductive resource allocation

Climate change, including ocean acidification (OA), presents fundamental challenges to marine biodiversity and sustained ecosystem health. We determined reproductive response (measured as naupliar production), cuticle composition and stage specific growth of the copepod Tisbe battagliai over three generations at four pH conditions (pH 7.67, 7.82, 7.95, and 8.06). Naupliar production increased significantly at pH 7.95 compared with pH 8.06 followed by a decline at pH 7.82. Naupliar production at pH 7.67 was higher than pH 7.82. We attribute the increase at pH 7.95 to an initial stress response which was succeeded by a hormesis-like response at pH 7.67. A multi-generational modelling approach predicted a gradual decline in naupliar production over the next 100 years (equivalent to approximately 2430 generations). There was a significant growth reduction (mean length integrated across developmental stage) relative to controls. There was a significant increase in the proportion of carbon relative to oxygen within the cuticle as seawater pH decreased. Changes in growth, cuticle composition and naupliar production strongly suggest that copepods subjected to OA-induced stress preferentially reallocate resources towards maintaining reproductive output at the expense of somatic growth and cuticle composition. These responses may drive shifts in life history strategies that favour smaller brood sizes, females and perhaps later maturing females, with the potential to profoundly destabilise marine trophodynamics.

Continue reading ‘Ocean acidification induces multi-generational decline in copepod naupliar production with possible conflict for reproductive resource allocation’

EP podcast: Ocean acidification (audio)

Human beings start domesticating crops only 12,000 or so years ago. Written history begins about 5,000 years ago. The modern era dates from — when? — maybe 100-200 years ago. Perhaps it’s no surprise, then, that we have some difficulty internalizing the idea that our burning carbon has, already, set into motion dramatic changes to the entire planet’s environment, changes that will persist for 100,000 years, or more. One of these is ocean acidification. Dr. Bärbel Hönisch and her co-authors of the paper “The Geological Record of Ocean Acidification,” Science (2 March, 2012), show that the rate of change of ocean acidification is greater today, by at least an order of magnitude, than it has ever been during any period over the past 300,000,000 years. Rate of change, not absolute pH level, being what matters. The deep past includes, notably, a couple of rapid ocean acidification/mass extinction events. This therefore, not unreasonably, should be of concern. Thanks, Bärbel! Total runtime fifty minutes. Potius sērō quam nunquam.

Continue reading ‘EP podcast: Ocean acidification (audio)’

Le zooplancton sous la menace du climat (in French)

À quel point l’acidification des océans menace-t-elle les organismes qui y vivent ? En Arctique, la fragilité d’un petit escargot planctonique, situé à la base de la chaîne alimentaire, préoccupe les biologistes.

Personne, il y a encore quatre ans, ne s’intéressait à ces minuscules escargots qui nagent dans l’océan Arctique : les ptéropodes Limacina helicina. Ils semblaient en effet si nombreux, atteignant par endroits plusieurs milliers d’individus par mètre carré, que leur sort ne suscitait aucune inquiétude. Une bonne nouvelle, car ces animaux représentent jusqu’à 90 % de la biomasse de zooplancton en Arctique. Mais c’était sans compter avec l’acidification des océans, qui résulte de la dissolution dans l’eau de mer d’une partie du dioxyde de carbone (CO2) atmosphérique : la coquille des ptéropodes est tout particulièrement sensible à ce phénomène. En avril 2012, cela vaudra à ces animaux une place de choix lors de la présentation finale des résultats du Programme de recherche européen sur l’acidification des océans (baptisé Epoca, selon son acronyme anglais), dédié à l’étude des conséquences de cette acidification (lire « L’acidification des océans sous surveillance », p. 81). Car selon son coordinateur, Jean-Pierre Gattuso, du laboratoire d’océanographie de Villefranche-sur-Mer : « Cette espèce est celle sur laquelle nous avons observé le plus d’effets négatifs dus à l’acidification. Ce qui permet de la considérer comme une espèce sentinelle de ce phénomène. » Explications en avant-première. Eaux de surface acides Chaque jour, les océans absorbent environ 22 millions de tonnes de CO2 émis par les activités humaines. Cela permet d’atténuer l’augmentation de l’effet de serre, mais avec un dommage collatéral : l’acidification des eaux de surface. Ainsi, le CO2 se dissout dans l’eau en formant des ions bicarbonates accompagnés d’ions hydrogène acidifiants. Résultat : depuis le début de la révolution industrielle, il y a deux cent cinquante ans, les eaux de surface s’acidifient. L’évolution de leur pH, l’unité de mesure de l’acidité, inversement corrélée à la concentration en ions hydrogène, le prouve. Entre la période préindustrielle et aujourd’hui, il est passé…
Continue reading ‘Le zooplancton sous la menace du climat (in French)’

Changes in pH at the exterior surface of plankton with ocean acidification

Anthropogenically released CO2 is dissolving in the ocean, causing a decrease in bulk-seawater pH (ocean acidification). Projections indicate that the pH will drop 0.3 units from its present value by 2100 (ref. 1). However, it is unclear how the growth of plankton is likely to respond. Using simulations we demonstrate how pH and carbonate chemistry at the exterior surface of marine organisms deviates increasingly from those of the bulk sea water as organism metabolic activity and size increases. These deviations will increase in the future as the buffering capacity of sea water decreases with decreased pH and as metabolic activity increases with raised seawater temperatures. We show that many marine plankton will experience pH conditions completely outside their recent historical range. However, ocean acidification is likely to have differing impacts on plankton physiology as taxon-specific differences in organism size, metabolic activity and growth rates during blooms result in very different microenvironments around the organism. This is an important consideration for future studies in ocean acidification as the carbonate chemistry experienced by most planktonic organisms will probably be considerably different from that measured in bulk-seawater samples. An understanding of these deviations will assist interpretation of the impacts of ocean acidification on plankton of different size and metabolic activity.

Continue reading ‘Changes in pH at the exterior surface of plankton with ocean acidification’

Acidification threatens Barrier Reef coral: researchers

A new study has found ocean acidification can affect the behaviour of baby corals in the Great Barrier Reef off Queensland.

University of Queensland (UQ) researchers have been analysing how ocean acidification affects the settlement of baby corals in the reef.

UQ Professor Peter Mumby says changes in the ocean are making the corals “stupid”.

“It implies that much of the biology of corals in terms of how they behave could be disrupted as the oceans change their chemistry,” he said.

Continue reading ‘Acidification threatens Barrier Reef coral: researchers’

Researchers think they have reason for low oyster production figured out (video)

Tillamook, Ore. — One of the Oregon coast’s biggest industries is being seriously threatened.

Recently, oyster hatcheries have seen a significant drop-off in production. During the last couple of years, researcher Alan Barton with the Whiskey Creek Shellfish Hatchery in Tillamook has been trying to figure out the reason behind the increase the high levels of acidity in the ocean. Oyster larvae are supposed to turn into this adult oyster, but researchers say the acidic ocean is a problem.

Continue reading ‘Researchers think they have reason for low oyster production figured out (video)’


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