Archive for November, 2011

Responses of marine benthic microalgae to elevated CO2

Increasing anthropogenic CO2 emissions to the atmosphere are causing a rise in pCO2 concentrations in the ocean surface and lowering pH. To predict the effects of these changes, we need to improve our understanding of the responses of marine primary producers since these drive biogeochemical cycles and profoundly affect the structure and function of benthic habitats. The effects of increasing CO2 levels on the colonisation of artificial substrata by microalgal assemblages (periphyton) were examined across a CO2 gradient off the volcanic island of Vulcano (NE Sicily). We show that periphyton communities altered significantly as CO2 concentrations increased. CO2 enrichment caused significant increases in chlorophyll a concentrations and in diatom abundance although we did not detect any changes in cyanobacteria. SEM analysis revealed major shifts in diatom assemblage composition as CO2 levels increased. The responses of benthic microalgae to rising anthropogenic CO2 emissions are likely to have significant ecological ramifications for coastal systems.

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Second International Symposium, Effects of Climate Change on the World’s Oceans – S10: Changes in the marine carbon cycle

S10: Changes in the marine carbon cycle

Convenors: James Christian (Department of Fisheries and Oceans, Canada) & Kitack Lee (POSTECH, Korea)

Plenary speaker: Ben McNeil (University of New South Wales, Australia)

Invited speaker: Dr. Masao Ishii (Meteorological Research Institute, Japan)

The carbon cycle is the primary mechanism by which ocean processes determine future atmospheric CO2 concentration and associated climate changes. Ocean acidification affects all marine biota and future ocean carbon fluxes and ocean-atmosphere CO2 exchange. This session invites all presentations on the ocean carbon cycle, its interactions with the biogeochemical cycles of nitrogen and other nutrient elements, and ocean acidification. Processes of interest include ocean-atmosphere exchange, fluxes across the pycnocline, interactions of CO2 with the carbon cycle that determine the future course of ocean acidification and ocean CO2 concentration, and acidification impacts on biota.

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Turning tides on ocean acidification

Marine researchers want to know the effects of an increasingly acidic ocean, and have turned to two tide pool dwellers for some insight. It appears that mussels and purple sea urchins could tell scientists how marine life might adapt to changes in ocean acidity (pH). These two key invertebrates have three things going for them: an intertidal home, a well-understood genome, and a calcium carbonate shell.

The rocky intertidal environment is in constant flux. During high tide seawater floods this zone, but after the tide ebbs the area between the tides is isolated from the rest of the ocean. Environmental conditions like temperature, salinity, and turbulence are not constant during the life of a mussel or a sea urchin. In addition to a daily flush of water, varying levels of oxygen and carbon dioxide make the intertidal a pretty dynamic place to live, chemically speaking. Because of these characteristics, MBARI researcher Francisco Chavez and his numerous collaborators attached pH sensors to this rocky habitat.

Chavez is measuring pH in the intertidal because, as he points out, “These organisms are seeing large swings of pH on a daily basis.” Daily variations of pH can occur from photosynthesis and from animals respiring and releasing carbon dioxide. The pH also fluctuates when upwelled water reaches the intertidal. During upwelling, colder deeper water that holds more carbon dioxide is brought to the surface just off the coast. In either case, increasing carbon dioxide increases the water’s acidity, thus lowering its pH.

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How does climate change influence arctic mercury?

Recent studies have shown that climate change is already having significant impacts on many aspects of transport pathways, speciation and cycling of mercury within Arctic ecosystems. For example, the extensive loss of sea-ice in the Arctic Ocean and the concurrent shift from greater proportions of perennial to annual types have been shown to promote changes in primary productivity, shift foodweb structures, alter mercury methylation and demethylation rates, and influence mercury distribution and transport across the ocean–sea-ice–atmosphere interface (bottom-up processes). In addition, changes in animal social behavior associated with changing sea-ice regimes can affect dietary exposure to mercury (top-down processes). In this review, we address these and other possible ramifications of climate variability on mercury cycling, processes and exposure by applying recent literature to the following nine questions; 1) What impact has climate change had on Arctic physical characteristics and processes? 2) How do rising temperatures affect atmospheric mercury chemistry? 3) Will a decrease in sea-ice coverage have an impact on the amount of atmospheric mercury deposited to or emitted from the Arctic Ocean, and if so, how? 4) Does climate affect air–surface mercury flux, and riverine mercury fluxes, in Arctic freshwater and terrestrial systems, and if so, how? 5) How does climate change affect mercury methylation/demethylation in different compartments in the Arctic Ocean and freshwater systems? 6) How will climate change alter the structure and dynamics of freshwater food webs, and thereby affect the bioaccumulation of mercury? 7) How will climate change alter the structure and dynamics of marine food webs, and thereby affect the bioaccumulation of marine mercury? 8) What are the likely mercury emissions from melting glaciers and thawing permafrost under climate change scenarios? and 9) What can be learned from current mass balance inventories of mercury in the Arctic? The review finishes with several conclusions and recommendations.

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C-CAN blog: NOAA ocean acidification mooring network

PI: Adrienne Sutton


     Research Institution: NOAA Pacific Marine Environmental Laboratory (PMEL)

     PI First name, Last name:  Adrienne Sutton

     Phone:                                206.526.6879


     Website link:


The focus of PMEL’s ocean carbon observation program is to document the evolving state of ocean carbon chemistry using measurements on ships and autonomous platforms, study the processes controlling the role of the ocean in the global carbon cycle, and investigate how rising atmospheric CO2 and climate change affect the chemistry of the oceans and its marine ecosystems.  Since ocean acidification emerged as an important scientific issue, the PMEL Carbon Group has been augmenting and expanding our observational capacity by adding pH and other biogeochemical sensors (O2, chlorophyll, turbidity) to a variety of observing platforms.  In particular, high frequency observations on moorings provide valuable information for better understanding natural variability in ocean acidification over daily to seasonal cycles. In addition, we have responded to the critical need for intensive time series measurements in highly productive coastal systems by focusing much of our initial efforts on upgrading coastal CO2 moorings around the U.S. to include ocean acidification measurements.  Our ocean acidification mooring network now includes 10 moorings in open ocean waters, coastal systems, and coral reefs.  The major goals of this research are to contribute to a better understanding of the temporal and spatial variability of carbon chemistry in the surface ocean and to expand the observational basis for developing predictions of future changes in ocean acidification and its consequences for marine ecosystems.

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C-CAN blog: Bodega ocean acidification research (BOAR)

PI: Tessa Hill, Brian Gaylord, Eric Sanford & Ann Russell


        Research Institution:            UC Bodega Marine Laboratory

        PI First name, Last name:      Tessa Hill, Brian Gaylord, Eric Sanford & Ann Russell 

        Phone:                                    (707) 875 1910


       Project website link :



The Bodega Ocean Acidification Research (BOAR) group (Professors Hill, Gaylord, Sanford & Russell) at the University of California Davis Bodega Marine Laboratory is a major research collaboration addressing the impacts of acidification on coastal upwelling and estuarine ecosystems. Using an interdisciplinary approach that draws on the expertise of oceanographers, marine chemists, and ecologists, we combine moored, shipboard and coastal measurements of seawater chemistry with controlled laboratory and field studies of ecological responses in key species. BML is situated on Bodega Head, a rocky headland within a major upwelling center where the effects of acidification may be exacerbated.

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Climate change impacts on the biophysics and economics of world fisheries

Global marine fisheries are underperforming economically because of overfishing, pollution and habitat degradation. Added to these threats is the looming challenge of climate change. Observations, experiments and simulation models show that climate change would result in changes in primary productivity, shifts in distribution and changes in the potential yield of exploited marine species, resulting in impacts on the economics of fisheries worldwide. Despite the gaps in understanding climate change effects on fisheries, there is sufficient scientific information that highlights the need to implement climate change mitigation and adaptation policies to minimize impacts on fisheries.

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Calcifying coral abundance near low-pH springs: implications for future ocean acidification

Rising atmospheric CO2 and its equilibration with surface ocean seawater is lowering both the pH and carbonate saturation state (Ω) of the oceans. Numerous calcifying organisms, including reef-building corals, may be severely impacted by declining aragonite and calcite saturation, but the fate of coral reef ecosystems in response to ocean acidification remains largely unexplored. Naturally low saturation (Ω ~ 0.5) low pH (6.70–7.30) groundwater has been discharging for millennia at localized submarine springs (called “ojos”) at Puerto Morelos, México near the Mesoamerican Reef. This ecosystem provides insights into potential long term responses of coral ecosystems to low saturation conditions. In-situ chemical and biological data indicate that both coral species richness and coral colony size decline with increasing proximity to low-saturation, low-pH waters at the ojo centers. Only three scleractinian coral species (Porites astreoides, Porites divaricata, and Siderastrea radians) occur in undersaturated waters at all ojos examined. Because these three species are rarely major contributors to Caribbean reef framework, these data may indicate that today’s more complex frame-building species may be replaced by smaller, possibly patchy, colonies of only a few species along the Mesoamerican Barrier Reef. The growth of these scleractinian coral species at undersaturated conditions illustrates that the response to ocean acidification is likely to vary across species and environments; thus, our data emphasize the need to better understand the mechanisms of calcification to more accurately predict future impacts of ocean acidification.

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OCB Newsletter: Impressions of the summer 2011 ocean acidification course at UW Friday Harbor labs

The graduate course at the University of Washington’s Friday Harbor Laboratories on Experimental Approaches to Understanding Ocean Acidification took place in June–July 2011. In an effort to expand the growing U.S. ocean acidification research community and facilitate the training of young scientists, OCB provided travel support for several U.S. students to participate in the Friday Harbor course. The last issue of OCB News included brief bios of each of these students. Below are some of their impressions of and reflections on the FHL course.

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OCB Newsletter: Spreading the word about ocean acidification: A journey to the Cape Cod Sea Camps

With a carload of cups, straws, seawater, red cabbage juice, bleach, lemon juice, seashells, yeast packets, and other miscellaneous items, I drove to the Cape Cod Sea Camps in Brewster, MA on a rainy day in mid-October to teach 36 7th graders from the Saint David’s School in NYC about ocean acidification. The inquisitive students proved to be quick studies and great sports, as they performed various experiments that demonstrated the concepts of pH and ocean acidification. We started with a brief presentation and Q&A session on ocean acidification and then broke into smaller groups that visited different “stations” around the room. At the “pH Demonstration” station, students used red cabbage juice, a natural pH indicator, to compare the pH of seawater with that of different household solutions such as bleach, vinegar, seltzer water, and lemon juice. At the “Ocean Acidification in a Cup” station, students used straws to bubble their exhaled CO2 into seawater and freshwater samples containing red cabbage juice pH indicator, watching the pH change right before their eyes. The “Yeast Experiment” station provided yet another opportunity to simulate ocean acidification. The students activated the yeast with warm water and sugar. Half of the group used a CO2 probe to directly monitor the CO2 being given off by the organisms, and the other half bubbled that CO2 gas into water and used a pH probe to monitor changes in the water pH. At the “Biological Impacts” station, students compared mollusk shells that had been soaked in just seawater (control) vs. acidified seawater. They looked at the shells under a microscope and also made observations of shell texture and brittleness. Students determined how many heavy books it took to break the control vs. acidified shells.
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Ocean acidification in the IPCC AR5 WG II

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