Archive for May, 2017

How coralline algae can still grow in acidified water

Photo credit: ARC, Australia

Reefkeepers who run calcium reactors and keep their tanks at a lower pH than natural seawater know that coralline algae is unphased by the acidified water. Research now shows why: Coralline algae is able to adjust its internal chemistry to continue the process of calcification.

Researchers have also shown that some corals are able to maintain constant pH within their calcifying fluids. The ability to adjust internal pH may help certain corals, coralline algae, and other reef life cope with ocean acidification as well as explain how SPS corals can grow so well even in pH-suppressed captive environments.

Reef-building algae adjusts internal chemistry in response to climate change

Researchers from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) have discovered that coralline algae, critical for the formation and maintenance of coral reefs, is able to adjust its internal chemistry favourably in response to ocean acidification.

Coralline algae are ecologically important. They form calcified skeletons for reefs by producing calcium carbonate, which acts as a “glue” to bind reefs together. However, rising levels of ocean acidity, as a result of human-induced climate change, is threatening this process.

Continue reading ‘How coralline algae can still grow in acidified water’

Living sustainably: acid’s impact – a “Teach for Our Energy Future” lesson

We sure use a lot of energy. About 97.4 quadrillion Btu a year just in the U.S. — roughly the equivalent of 16 billion barrels of oil. And all that energy use has direct impact on our planet’s oceans, making them warmer and more acidic. But do we really understand how our lifestyle choices creates that impact?

Most of our energy comes from ancient dead things that became crude oil, coal and natural gas. Burning those fuels releases carbon dioxide into the atmosphere, which in turn traps heat in the atmosphere — the “greenhouse effect.” At the same time, the more we burn carbon-based fuels, the more carbon dioxide the oceans absorb, making them more acidic. Since the beginning of the Industrial Revolution in the 18th Century, the ocean surface has experienced a 30 percent increase in acidity.

Among other things, sea life is affected. A simple experiment can show acidification’s impact on life such as coral, clams and oysters — creatures with calcium carbonate skeletons.

Continue reading ‘Living sustainably: acid’s impact – a “Teach for Our Energy Future” lesson’

Conservation of Brazilian coral reefs in the Southwest Atlantic Ocean: a change of approach

Brazil has the most extensive and richest areas of coral reefs in the South Atlantic Ocean, with its fauna characterized by high endemism and adaptations related to its growth and morphology, to its coral building fauna and to the depositional environment that differ from other coral reefs around the world. In spite of the effects from changes in the global environmental, the main stress factors for Brazilian reefs are local level threats, such as pollution and overfishing. The effects from these threats reduce biodiversity and result in decreasing stocks at different trophic levels. The trend that currently exists, regarding marine resource use, implies that reassessing the conservation strategies is urgently necessary if the degradation of these environments is to be reversed. It is necessary that the practices used in adjacent watersheds be improved, combined with actions to protect and recover native vegetation, along with planning for developing coastal areas, which will ensure that sedimentation rates be controlled and pollution sources are drastically reduced. Brazil should have to adopt a multidisciplinary approach to lead an evolution from traditional threat management in individual portions of ecosystems to large-scale management strategies in complex socio-economic and natural systems.

Continue reading ‘Conservation of Brazilian coral reefs in the Southwest Atlantic Ocean: a change of approach’

West Coast study suggests long term impacts of ocean acidification (audio and text)

There’s a new study of the effects of ocean acidification on tiny shell-forming sea creatures in northern California. The findings suggest the ongoing buildup of carbon dioxide in the Earth’s atmosphere could set up a destructive feedback loop with the deep ocean. And that could disrupt natural cycles for centuries to come.

The study – from the University of California Davis – found that a common type of plankton had trouble growing and repairing their shells in acidic water. This was surprising, says researcher Catherine Davis, since the waters off the Pacific coast are often more acidic than in many other places because of currents that cycle water from the deep ocean back to the surface.

“And since these organisms were from the Pacific Coast, we might actually expect them to be more tolerant to low pH conditions,” Davis said. “And what we found was that was not the case.”
Davis says normally, when these creatures die, their shells sink to the ocean floor. There, the calcite in the shells helps counteract the acidity of the deep ocean water. Skimpier shells means less calcite gets to the ocean floor, leaving the deep ocean more acidic.”

Continue reading ‘West Coast study suggests long term impacts of ocean acidification (audio and text)’

Decrease impacts of ocean acidification

By adopting the new national programs for renewable energy and energy efficiency, Algeria is committed to reducing 9% of its global consumption of energy by 2030. These ambitious programs aim to engage thermal insulation of an important housing program, as well as to convert to liquefied petroleum gas one million of light-duty vehicles and more than 20.000 buses.

Algeria, being the largest country in Africa, in the Mediterranean and in the Arab world, has one of the highest solar deposits in the world, estimated to exceed five billion GWh/year. The annual sunshine duration is estimated to be around 2 500 hours on average and could exceed 3 600 hours in some parts of the country.

By 2030, Algeria aspires to the deployment, on a large scale, of photovoltaic and wind power as well as thermal solar energy, and the integration of cogeneration, biomass, and geothermal energy. This program ultimately aims to reach the target of 27% of the electricity produced nationally generated from renewable sources of energy. The action plan of the government aspires also to reduce gas flaring to less than 1%, by 2030.

Like many countries in its region, Algeria is affected by desertification and land degradation. Most of the country is arid or semi- arid. The areas receiving more than 400 mm of rain per year are located in a narrow strip along the coast, not exceeding 150 km large. Moreover, due to climate change, yearly average rainfall declined by more than 30% over the past decades.

Continue reading ‘Decrease impacts of ocean acidification’

Reef-building corals thrive within hot-acidified and deoxygenated waters

Coral reefs are deteriorating under climate change as oceans continue to warm and acidify and thermal anomalies grow in frequency and intensity. In vitro experiments are widely used to forecast reef-building coral health into the future, but often fail to account for the complex ecological and biogeochemical interactions that govern reefs. Consequently, observations from coral communities under naturally occurring extremes have become central for improved predictions of future reef form and function. Here, we present a semi-enclosed lagoon system in New Caledonia characterised by diel fluctuations of hot-deoxygenated water coupled with tidally driven persistently low pH, relative to neighbouring reefs. Coral communities within the lagoon system exhibited high richness (number of species = 20) and cover (24–35% across lagoon sites). Calcification rates for key species (Acropora formosa, Acropora pulchra, Coelastrea aspera and Porites lutea) for populations from the lagoon were equivalent to, or reduced by ca. 30–40% compared to those from the reef. Enhanced coral respiration, alongside high particulate organic content of the lagoon sediment, suggests acclimatisation to this trio of temperature, oxygen and pH changes through heterotrophic plasticity. This semi-enclosed lagoon therefore provides a novel system to understand coral acclimatisation to complex climatic scenarios and may serve as a reservoir of coral populations already resistant to extreme environmental conditions.

Continue reading ‘Reef-building corals thrive within hot-acidified and deoxygenated waters’

Technical Note: A minimally invasive experimental system for pCO2 manipulation in plankton cultures using passive gas exchange (atmospheric carbon control simulator) (update)

As research into the biotic effects of ocean acidification has increased, the methods for simulating these environmental changes in the laboratory have multiplied. Here we describe the atmospheric carbon control simulator (ACCS) for the maintenance of plankton under controlled pCO2 conditions, designed for species sensitive to the physical disturbance introduced by the bubbling of cultures and for studies involving trophic interaction. The system consists of gas mixing and equilibration components coupled with large-volume atmospheric simulation chambers. These chambers allow gas exchange to counteract the changes in carbonate chemistry induced by the metabolic activity of the organisms. The system is relatively low cost, very flexible, and when used in conjunction with semi-continuous culture methods, it increases the density of organisms kept under realistic conditions, increases the allowable time interval between dilutions, and/or decreases the metabolically driven change in carbonate chemistry during these intervals. It accommodates a large number of culture vessels, which facilitate multi-trophic level studies and allow the tracking of variable responses within and across plankton populations to ocean acidification. It also includes components that increase the reliability of gas mixing systems using mass flow controllers.

Continue reading ‘Technical Note: A minimally invasive experimental system for pCO2 manipulation in plankton cultures using passive gas exchange (atmospheric carbon control simulator) (update)’

Estuarine sediment resuspension and acidification: Release behaviour of contaminants under different oxidation levels and acid sources

Carbon dioxide (CO2) Capture and Storage (CCS) is a technology to reduce the emissions of this gas to the atmosphere by sequestering it in geological formations. In the case of offshore storage, unexpected CO2 leakages will acidify the marine environment. Reductions of the pH might be also caused by anthropogenic activities or natural events such as acid spills and dredging operations or storms and floods. Changes in the pH of the marine environment will trigger the mobilisation of elements trapped in contaminated shallow sediments with unclear redox boundary. Trace element (As, Cd, Cr, Cu, Ni, Pb and Zn) release from anoxic and oxic estuarine sediment is analysed and modelled under different laboratory acidification conditions using HNO3 (l) and CO2 (g): acidification at pH = 6.5 as worst-case scenario in events of CO2 leakages and acid spills, and acidification at pH = 7.0 as a seawater scenario under CO2 leakages, acid spills, as well as sediment resuspension. The prediction of metal leaching behaviour appear to require sediment specific and site specific tools. In the present work it is demonstrated that the proposed three in-series reactions model predicts the process kinetics of the studied elements under different simulated environmental conditions (oxidation levels and acid sources). Differences between HNO3 and CO2 acidification are analysed through the influence of the CO2 gas on the ionic competition of the medium. The acidification with CO2 provokes higher released concentrations from the oxic sediment than from the anoxic sediment, except in the case of Zn, which influences the release of the other studied elements. Slight acidification can endanger the aquatic environment through an important mobilisation of contaminants. The obtained prediction of the contaminant release from sediment (kinetic parameters and maximum concentrations) can contribute to the exposure assessment stage for risk management and preincidental planning in accidental CO2 leakages and chemical spills scenarios.

Continue reading ‘Estuarine sediment resuspension and acidification: Release behaviour of contaminants under different oxidation levels and acid sources’

Spatial patterns of Anchoveta (Engraulis ringens) eggs and larvae in relation to pCO2 in the Peruvian upwelling system

Large and productive fisheries occur in regions experiencing or projected to experience ocean acidification. Anchoveta (Engraulis ringens) constitute the world’s largest single-species fishery and live in one of the ocean’s highest pCO2 regions. We investigated the relationship of the distribution and abundance of Anchoveta eggs and larvae to natural gradients in pCO2 in the Peruvian upwelling system. Eggs and larvae, zooplankton, and data on temperature, salinity, chlorophyll a and pCO2 were collected during a cruise off Peru in 2013. pCO2 ranged from 167–1392 µatm and explained variability in egg presence, an index of spawning habitat. Zooplankton abundance explained variability in the abundance of small larvae. Within the main spawning and larva habitats (6–10°S), eggs were found in cool, low-salinity, and both extremely low (less than 200 µatm) and high (more than 900 µatm) pCO2 waters, and larvae were collected in warmer, higher salinity, and moderate (400–600 µatm) pCO2 waters. Our data support the hypothesis that Anchoveta preferentially spawned at high pCO2 and these eggs had lower survival. Enhanced understanding of the influence of pCO2 on Anchoveta spawning and larva mortality, together with pCO2 measurements, may enable predictions of ocean acidification effects on Anchoveta and inform adaptive fisheries management.

Continue reading ‘Spatial patterns of Anchoveta (Engraulis ringens) eggs and larvae in relation to pCO2 in the Peruvian upwelling system’

Tiny shells indicate big changes to global carbon cycle

Experiments with tiny, shelled organisms in the ocean suggest big changes to the global carbon cycle are underway, according to a study from the University of California, Davis. For the study, published in the journal Scientific Reports, scientists raised foraminifera — single-celled organisms about the size of a grain of sand — at the UC Davis Bodega Marine Laboratory under future, high CO2 conditions. These tiny organisms, commonly called “forams,” are ubiquitous in marine environments and play a key role in food webs and the ocean carbon cycle.

Stressed Under Future Conditions

After exposing them to a range of acidity levels, UC Davis scientists found that under high CO2, or more acidic, conditions, the foraminifera had trouble building their shells and making spines, an important feature of their shells. They also showed signs of physiological stress, reducing their metabolism and slowing their respiration to undetectable levels.

This is the first study of its kind to show the combined impact of shell building, spine repair, and physiological stress in foraminifera under high CO2 conditions. The study suggests that stressed and impaired foraminifera could indicate a larger scale disruption of carbon cycling in the ocean.

Continue reading ‘Tiny shells indicate big changes to global carbon cycle’

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Ocean acidification in the IPCC AR5 WG II

OUP book