Archive for April, 2013

Biological impacts of enhanced alkalinity in Carcinus maenas

Further steps are needed to establish feasible alleviation strategies that are able to reduce the impacts of ocean acidification, whilst ensuring minimal biological side-effects in the process. Whilst there is a growing body of literature on the biological impacts of many other carbon dioxide reduction techniques, seemingly little is known about enhanced alkalinity. For this reason, we investigated the potential physiological impacts of using chemical sequestration as an alleviation strategy. In a controlled experiment, Carcinus maenas were acutely exposed to concentrations of Ca(OH)2 that would be required to reverse the decline in ocean surface pH and return it to pre-industrial levels. Acute exposure significantly affected all individuals’ acid–base balance resulting in slight respiratory alkalosis and hyperkalemia, which was strongest in mature females. Although the trigger for both of these responses is currently unclear, this study has shown that alkalinity addition does alter acid–base balance in this comparatively robust crustacean species.

Continue reading ‘Biological impacts of enhanced alkalinity in Carcinus maenas’

Symbiosis increases coral tolerance to ocean acidification

Increasing the acidity of ocean waters will directly threaten calcifying marine organisms such as reef-building scleractinian corals, and the myriad of species that rely on corals for protection and sustenance. Ocean pH has already decreased by around 0.1 pH units since the beginning of the industrial revolution, and is expected to decrease by another 0.2–0.4 pH units by 2100. This study mimicked the pre-industrial, present, and near-future levels of pCO2 using a precise control system (±5% pCO2), to assess the impact of ocean acidification on the calcification of recently-settled primary polyps of Acropora digitifera, both with and without symbionts, and adult fragments with symbionts. The increase in pCO2 of 100 μatm between the pre-industrial period and the present had more effect on the calcification rate of adult A. digitifera than the anticipated future increases of several hundreds of micro-atmospheres of pCO2. The primary polyps with symbionts showed higher calcification rates than primary polyps without symbionts, suggesting that (i) primary polyps housing symbionts are more tolerant to near-future ocean acidification than organisms without symbionts, and (ii) corals acquiring symbionts from the environment (i.e. broadcasting species) will be more vulnerable to ocean acidification than corals that maternally acquire symbionts.

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Cobia Micro-CT “Flythrough” (video)

Unique 3D X-ray (Micro-CT scan) imagery of a 22 day old larval cobia (Rachycentron canadum) was used to extract in situ measurements of otolith (ear stone) size and density. The resulting data identified increased otolith size and density in fish raised under decreased-pH ocean acidification conditions. Based on mathematical modeling of otolith function, these changes (up to 58% greater mass otoliths) cause an increase in hearing sensitivity and as much as a 50% increase in hearing range. See more in the PNAS article by Bignami et al. (2013).

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The emergence of a scientific community with “xFOCE”

The acidity of the oceans is increasing. CO2, released in great amounts by human activity and partly captured by the world’s seas, is implicated. Scientists are now getting organised in an effort to understand the impact of this phenomenon on marine ecosystems, for they are facing a daunting technological challenge: they must set up a laboratory on the seabed to measure the effect of ocean acidification on the species living there

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“xFOCE”, l’émergence d’une communauté scientifique (in French)

Les océans deviennent de plus en plus acides. En cause, le CO2 libéré en quantité croissante par les activités humaines. Pour comprendre l’impact de ce phénomène sur les écosystèmes marins, les scientifiques s’organisent autour de la planète. Comme en Europe, où le projet eFoce, soutenu par la Fondation BNP Paribas, fédère plusieurs équipes autour du Laboratoire d’océanographie de Villefranche. Avec un système open source conçu par des chercheurs californiens et un maillage international, une nouvelle communauté scientifique émerge.

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Blaine fifth-graders learn impact of pollution on marine habitat

BLAINE – Kylie Crawford held her nose as she blew into a straw dipped in purple water for her classroom’s study of ocean acidification.

The distilled water was colored by the red cabbage that had been boiled in it. Judging by Kylie, and the reaction of the other students in her fifth-grade class at Blaine Elementary School, the smell of the bubbling water was off-putting.

But the cabbage water was there to help the students see what happens when carbon dioxide – from their breath as they blow into the straw – dissolves in the small amount of water. It makes acid, which turns the liquid’s color in their cups from purple to pink.

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News in brief: some like it acidic

In a world of altered oceans, a shelled plankton species may flourish

As carbon dioxide levels in the air rise and turn the oceans more acidic, some forms of life may thrive, not suffer. Shelled plankton could be resilient in higher-carbon conditions, new research finds.

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Early exposure of bay scallops (Argopecten irradians) to high CO2 causes a decrease in larval shell growth

Ocean acidification, characterized by elevated pCO2 and the associated decreases in seawater pH and calcium carbonate saturation state (Ω), has a variable impact on the growth and survival of marine invertebrates. Larval stages are thought to be particularly vulnerable to environmental stressors, and negative impacts of ocean acidification have been seen on fertilization as well as on embryonic, larval, and juvenile development and growth of bivalve molluscs. We investigated the effects of high CO2 exposure (resulting in pH = 7.39, Ωar = 0.74) on the larvae of the bay scallop Argopecten irradians from 12 h to 7 d old, including a switch from high CO2 to ambient CO2 conditions (pH = 7.93, Ωar = 2.26) after 3 d, to assess the possibility of persistent effects of early exposure. The survival of larvae in the high CO2 treatment was consistently lower than the survival of larvae in ambient conditions, and was already significantly lower at 1 d. Likewise, the shell length of larvae in the high CO2 treatment was significantly smaller than larvae in the ambient conditions throughout the experiment and by 7 d, was reduced by 11.5%. This study also demonstrates that the size effects of short-term exposure to high CO2 are still detectable after 7 d of larval development; the shells of larvae exposed to high CO2 for the first 3 d of development and subsequently exposed to ambient CO2 were not significantly different in size at 3 and 7 d than the shells of larvae exposed to high CO2 throughout the experiment.

Continue reading ‘Early exposure of bay scallops (Argopecten irradians) to high CO2 causes a decrease in larval shell growth’

EPA urged to toughen standards to protect marine life from ocean acidification

SAN FRANCISCO–(ENEWSPF)–April 17 – In a legal petition to the Environmental Protection Agency, the Center for Biological Diversity today sought better, more effective standards to protect shellfish, corals and other marine life from the corrosive and deadly effects of ocean acidification. The state of Washington recently stated it hoped EPA would set such standards, in order to help shellfish hatcheries avoid future oyster die-offs. The petition also asks that the EPA publish guidance to help states effectively monitor and protect their coastal waters from ocean acidification.

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Can acid neutralizers help coral reefs bounce back? (audio)

Coral reefs are in trouble worldwide, from a host of threats, including warming ocean temperatures, nutrient runoff and increasing ocean acidity. A noted climate scientist from California has been conducting an experiment on Australia’s Great Barrier Reef to see whether antacid could boost coral growth.

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Ocean acidification in the IPCC AR5 WG II

OUP book