Archive for November, 2016

Coral biomineralization, climate proxies and the sensitivity of coral reefs to CO2-driven climate change

Scleractinian corals extract calcium (Ca2+) and carbonate (CO2−3) ions from seawater to construct their calcium carbonate (CaCO3) skeletons. Key to the coral biomineralization process is the active elevation of the CO2−3 concentration of the calcifying fluid to achieve rapid nucleation and growth of CaCO3 crystals. Coral skeletons contain valuable records of past climate variability and contribute to the formation of coral reefs. However, limitations in our understanding of coral biomineralization hinder the accuracy of (1) coral-based reconstructions of past climate, and (2) predictions of coral reef futures as anthropogenic CO2 emissions drive declines in seawater CO2−3 concentration. In this thesis, I investigate the mechanism of coral biomineralization and evaluate the sensitivity of coral reef CaCO3 production to seawater carbonate chemistry. First, I conducted abiogenic CaCO3 precipitation experiments that identified the U/Ca ratio as a proxy for fluid CO2−3 concentration. Based on these experimental results, I developed a quantitative coral biomineralization model that predicts temperature can be reconstructed from coral skeletons by combining Sr/Ca – which is sensitive to both temperature and CO2−3 – with U/Ca into a new proxy called “Sr-U”. I tested this prediction with 14 corals from the Pacific Ocean and the Red Sea spanning mean annual temperatures of 25.7-30.1°C and found that Sr-U has uncertainty of only 0.5°C, twice as accurate as conventional coral-based thermometers. Second, I investigated the processes that differentiate reef-water and open-ocean carbonate chemistry, and the sensitivity of ecosystem-scale calcification to these changes. On Dongsha Atoll in the northern South China Sea, metabolic activity of resident organisms elevates reef-water CO2−3 twice as high as the surrounding open ocean, driving rates of ecosystem calcification higher than any other coral reef studied to date. When high temperatures stressed the resident coral community, metabolic activity slowed, with dramatic effects on reef-water chemistry and ecosystem calcification. Overall, my thesis highlights how the modulation of CO2−3, by benthic communities on the reef and individual coral polyps in the colony, controls the sensitivity of coral reefs to future ocean acidification and influences the climate records contained in the skeleton.

Continue reading ‘Coral biomineralization, climate proxies and the sensitivity of coral reefs to CO2-driven climate change’

The stable microbiome of inter and sub-tidal anemone species under increasing pCO2

Increasing levels of pCO2 within the oceans will select for resistant organisms such as anemones, which may thrive under ocean acidification conditions. However, increasing pCO2 may alter the bacterial community of marine organisms, significantly affecting the health status of the host. A pH gradient associated with a natural volcanic vent system within Levante Bay, Vulcano Island, Italy, was used to test the effects of ocean acidification on the bacterial community of two anemone species in situ, Anemonia viridis and Actinia equina using 16 S rDNA pyrosequencing. Results showed the bacterial community of the two anemone species differed significantly from each other primarily because of differences in the Gammaproteobacteria and Epsilonproteobacteria abundances. The bacterial communities did not differ within species among sites with decreasing pH except for A. viridis at the vent site (pH = 6.05). In addition to low pH, the vent site contains trace metals and sulfide that may have influenced the bacteria community of A. viridis. The stability of the bacterial community from pH 8.1 to pH 7.4, coupled with previous experiments showing the lack of, or beneficial changes within anemones living under low pH conditions indicates that A. viridis and A. equina will be winners under future ocean acidification scenarios.

Continue reading ‘The stable microbiome of inter and sub-tidal anemone species under increasing pCO2’

The invisible ocean threat that ripples through the food chain (audio and text)

GWEN IFILL: While global leaders meet to discuss action on climate change, one new threat has emerged in the world’s oceans.

As Scott Shafer from our San Francisco station KQED reports, the threat may not be visible to the naked eye, but it changes the very chemistry of essential parts of the marine ecosystem.

SCOTT SHAFER, KQED: Coral reefs like these, vibrant and teeming with life, may hold clues to the future of the world’s oceans.

STEPHEN PALUMBI, Hopkins Marine Station, Stanford University: Coral reefs only make up a fraction of 1 percent of the ocean, but they hold 25 percent of the ocean’s species. Not only that, but they feed hundreds of millions of people, and a billion people or more get some income from coral reefs. So this is an ecosystem that is really fundamental to humans on the planet.

SCOTT SHAFER: Steve Palumbi is the director of Stanford University’s Hopkins Marine Station. He has studied coral reefs around the world.

For decades, warming ocean waters have damaged, even killed coral. But Palumbi says reefs are now facing an insidious threat from a chemical change that is making ocean water more acidic.

STEPHEN PALUMBI: Ocean acidification affects the entire globe’s oceans. And it affects organisms by reducing their growth rate and by making it more difficult to make shells. We know that fish actually react to dangers differently.

Continue reading ‘The invisible ocean threat that ripples through the food chain (audio and text)’

Statement by The Nature Conservancy on New York State addressing ocean acidification

The Nature Conservancy applauds Governor Cuomo and the New York State Legislature for creating an Ocean Acidification Task Force.

Albany, NY | November 29, 2016The Nature Conservancy in New York released the following statement from Stuart F. Gruskin, Chief Conservation and External Affairs Officer, regarding today’s announcement of New York State taking steps to address the critical threat of ocean acidification:

“We commend Governor Cuomo and the New York State Legislature for their leadership on ocean acidification, a pressing water quality and climate threat. The law signed yesterday will address a serious yet invisible threat to our economy, our food security, and our fishing and tourism industries. Ocean acidification, caused by the burning of fossil fuels, puts marine life and people at risk. New York, including our shellfishing industry, is especially vulnerable, due to waters already contaminated with high levels of nitrogen from wastewater.

Continue reading ‘Statement by The Nature Conservancy on New York State addressing ocean acidification’

Ocean acidification threatens Alaska waters, workshop to be screened in Sitka (audio and text)

The world’s oceans are becoming more acidic and, like climate change, it’s happening at a faster rate in the far north waters of Alaska. A workshop held in Anchorage Wednesday (11-30-16) aims to bring together scientists and stakeholders to better understand the threat ocean acidification poses to the state. As KCAW’s Emily Russell reports, the workshop is being streamed in nine other communities around the state, including Sitka.

Not only are the world’s oceans about 30 percent more acidic today than they were three hundred years ago, the rate at which they’re acidifying is faster than at any other time on record.

Chris Whitehead is the environmental program manager for the Sitka Tribe of Alaska.

“So, more carbon in the air getting absorbed by seawater makes it more acidic,” explained Whitehead of ocean acidification.

The Tribe has been testing toxins in shellfish for years, but soon it  will start testing the waters for levels of acidity. According to Whitehead, ocean acidification poses a particular threat to marine animals at the bottom of the food chain.

Continue reading ‘Ocean acidification threatens Alaska waters, workshop to be screened in Sitka (audio and text)’

New York creates ocean acidification task force

Governor Cuomo has given fresh hope to all of us who use and love New York’s ocean by signing into law A. 10264/ S. 7908, which establishes a state ocean acidification task force.

Awareness of the impacts of ocean acidification – the so-called “evil twin” of global warming – is just beginning, but we know:

  • Acidic water makes it harder for many species of shell-building organisms like oysters and scallops to grow their protective coverings and survive.
  • Ocean acidification could be having an impact on important recreational fish like summer flounder (fluke) and other fish species as well.
  • New York is one of the states most vulnerable to ocean acidification, due to our economic dependence on shellfish harvesting and because our waters have high levels of nitrogen pollution, which amplifies acidification.

Given the uncertainty of future action at the Federal level, it is more important than ever that states like New York lead in tackling climate change and interconnected challenges like ocean acidification.

Continue reading ‘New York creates ocean acidification task force’

As warming seas menace fish, communities seek ways to stay afloat

MARRAKESH, Morocco, Nov 25 (Thomson Reuters Foundation) – When nearly all the young oyster crop died two years in a row at shellfish farms in the U.S. Pacific Northwest, workers at first suspected a virus.

But the real culprit was a new worry: a change in the acidity of the sea water feeding the oyster tanks.

As the world’s oceans absorb carbon dioxide that is building up in the atmosphere, seas have become 30 percent more acidic than they were before the industrial era, said Carol Turley, a senior scientist at Britain’s Plymouth Marine Laboratory.

The increasingly corrosive water threatens a wide range of sea life, particularly shellfish such as oysters and scallops, making it hard for them to form and maintain shells.

Warming of the world’s oceans, as they absorb rising heat associated with climate change, also is killing coral reefs and driving more fish species toward cooler seas and away from the regions where they have traditionally lived and been caught, Turley said on the sidelines of the recent U.N. climate talks in Marrakesh.

Continue reading ‘As warming seas menace fish, communities seek ways to stay afloat’

Fish found to thrive in high levels of CO2

While rising CO2 levels have been shown to harm wild fish, shellfish and corals at sea, farmed fish can thrive in similar conditions.

British scientists have identified a paradox in research on the impact of extra carbon dioxide on the world’s oceans.

There is no doubt that along with global warming the oceans are becoming more acidic, and that this badly affects fish, corals and shellfish. But researchers have found that “closed system” fish farmers who recycle the same water are already keeping fish healthy at carbon dioxide concentrations higher than predicted for climate change. And fish farming is the fastest growing branch of the food industry, increasing at more than 8% a year for the last 30 years.

So, argue Robert Ellis and Rod Wilson of the UK’s University of Exeter, and Mauricio Urbina of the University of Canterbury in Christchurch, New Zealand, in the journal Global Change Biology, there are new questions to be resolved. Can ocean fish adapt to ocean acidification? Or is the species selected as suitable for fish farming just naturally more tolerant of the conditions that the world will face by the close of the century?

Continue reading ‘Fish found to thrive in high levels of CO2’

2017 OCB Activity Solicitation

The Ocean Carbon and Biogeochemistry (OCB) Program is soliciting proposals for OCB activities to begin during the 2017 calendar year.  We seek proposals for OCB-relevant scoping workshops and smaller group activities as follows:

  • Scoping workshops (50-60 people) that bring together an appropriate body of expertise to foster discussions and develop forward momentum in a specific OCB-relevant research area
  • Small working groups (8-12 members) to address targeted science goals/questions and develop products that benefit the broader OCB community
  • Synthesis activities to assimilate existing data, model outputs, etc. to support and inform future research efforts
  • Intercomparison activities to compare and build consensus on approaches (methodological, modeling, data analysis, etc.) for advancing OCB-relevant research

Please visit the OCB website to learn about previous scoping workshops and other activities. OCB has recently led numerous workshops and scientific planning activities that have generated guidelines and recommendations for future research in OCB-relevant research areas; however, proposals need not be limited to these topics:

Continue reading ‘2017 OCB Activity Solicitation’

The effects of pressure on pH of Tris buffer in synthetic seawater

Equimolar Tris (2-amino-2-hydroxymethyl-propane-1,3-diol) buffer prepared in artificial seawater media is a widely accepted pH standard for oceanographic pH measurements, though its change in pH over pressure is largely unknown. The change in volume (ΔV) of dissociation reactions can be used to estimate the effects of pressure on the dissociation constant of weak acid and bases. The ΔV of Tris in seawater media of salinity 35 (ΔVTris⁎) was determined between 10 and 30 °C using potentiometry. The potentiometric cell consisted of a modified high pressure tolerant Ion Sensitive Field Effect Transistor pH sensor and a Chloride-Ion Selective Electrode directly exposed to solution. The effects of pressure on the potentiometric cell were quantified in aqueous HCl solution prior to measurements in Tris buffer. The experimentally determined ΔVTris⁎ were fitted to the equation ΔVTris⁎ = 4.528 + 0.04912t where t is temperature in Celsius; the resultant fit agreed to experimental data within uncertainty of the measurements, which was estimated to be 0.9 cm− 3 mol− 1. (…)

Continue reading ‘The effects of pressure on pH of Tris buffer in synthetic seawater’

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Ocean acidification in the IPCC AR5 WG II

OUP book