Archive for March, 2015

Training course “Effects of Ocean Acidification and Global Warming on Mediterranean Marine Organisms: in situ and laboratory experiment on selected calcifying taxa”, September 2015, Italy

Dates and location: 2-10 September 2015, Regional Natural Park of Porto Venere, La Spezia, Italy
Language: English
Attendance and study mode: Campus / Full time
Available places: min 8 – max 15

The course aims to introduce students to the theme of global climate changes in the Mediterranean Sea and with particular emphasis to coralline algae, and bryozoans, biomineralizers from the Gulf of La Spezia. The course will held in the Regional Natural Park of Porto Venere (La Spezia, Italy) and it will be based on seminars and fieldwork activities. Students will be based on Palmaria Island for 10 days, where they will perform field work activities and attend seminars. Two-day visit at the ENEA Laboratory will be organized for showing to the students the experimental activities are conducted on taxa from the area under controlled conditions.

Seminars will focus on  the effects of climate changes on Mediterranean bioconstructors, with an introduction on Mediterranean marine chemistry, overview about the effects of acidification on Mediterranean biota and a special focus will be given coralline algae and bryozoans as model organisms in climate change studies.

Continue reading ‘Training course “Effects of Ocean Acidification and Global Warming on Mediterranean Marine Organisms: in situ and laboratory experiment on selected calcifying taxa”, September 2015, Italy’

The ecology of ocean acidification: integrating the effects of pH variation among other environmental stressors on biogeography and organismal performance in rocky intertidal communities

Ocean Acidification (OA) has emerged as a major threat to marine ecosystems, particularly regarding calcifying organisms. A growing body of literature describing laboratory investigations into pH stress indicates broadly deleterious effects for calcifiers, but responses vary greatly across taxa and can be influenced by variations in other environmental characteristics. Scaling laboratory results to ecological performance is critical for understanding the impacts of OA on marine communities. One method that can be useful for elucidating these ecological impacts is to study organisms and communities in environments that naturally vary in pH. The California Current Large Marine Ecosystem (CCLME) is one such ecosystem in which pH varies both in space and over time, bathing intertidal communities in a mosaic of pH conditions. The dynamics of the CCLME during the upwelling season also drive biologically-relevant variation in productivity and temperature.

My dissertation leverages variation in oceanographic processes along the CCLME to explore the potential for OA impacts on rocky intertidal community distributions and the performances of two major space occupiers in rocky intertidal communities. In Chapter 2, a series of large scale community surveys along the CCLME were re-examined to ask if distributions of calcifiers and their mineral forms differ whether these differences are linked to environmental conditions. The patterns of differential calcifier abundances that emerge may better inform studies into the potential community impacts of OA by highlighting regions where calcifiers are relatively diverse or replete. Although these patterns are partially driven by complex interactions among temperature, phytoplankton productivity and upwelling, much of the spatial variation in calcifier abundance remains unexplained, suggesting the need to better characterize the pH environment along this oceanographically-complex region.

In Chapter 3, I explored the relative influence of the pH mosaic along the CCLME on performance of the California mussel, Mytilus californianus. When considered along with other known stressors such as temperature and chlorophyll-a variations, pH meaningfully contributed toward explaining variation in mussel growth, condition and shell thickness. Contrary to expectation, some aspects of mussel performance were enhanced at comparatively low pH sites. The potential implications of this work include mediation of pH stress by other environmental factors, energetic trade-offs between calcified and soft tissue development, a life history transition toward increased resilience, and genotypic or persistent phenotypic differences that integrate exposure history.

In Chapter 4, I investigated the relative influence of natural pH variation on performance of the purple sea urchin, Strongylocentrotus purpuratus. As with the California mussel study in Chapter 3, aspects of sea urchin calcified structures were enhanced, not suppressed as expected, at sites with comparatively low pH, after considering the effects of algal consumption and mean temperature. The combined results of Chapters 3 and 4 underscore the complex interactions between multiple environmental stressors and organismal physiology, highlight the biological relevance of pH on ecological performance, and suggest that life in areas already subject to natural pH variation may have the adaptive capacity to persist under future conditions.

Continue reading ‘The ecology of ocean acidification: integrating the effects of pH variation among other environmental stressors on biogeography and organismal performance in rocky intertidal communities’

Macroalgae contribute to nested mosaics of pH variability in a sub-Arctic fjord

The Arctic Ocean is considered the most vulnerable ecosystem to ocean acidification (OA) and large-scale assessments of pH and the saturation state for aragonite (Ωarag) indicate that it is already close to corrosive states (Ωarag < 1). In high-latitude coastal waters the regulation of pH and Ωarag is far more complex than offshore because increased biological activity and input of glacial meltwater affect pH. As most calcifiers occupy coastal habitats, the assessment of risks from OA to these vulnerable organisms cannot be derived from extrapolation of current and forecasted offshore conditions, but requires an understanding of the regimes of pH and Ωarag in their coastal habitats. To increase knowledge of the natural variability of pH in the Arctic coastal zone and specifically to test the influence of benthic vegetated habitats, we quantified pH-variability in a Greenland fjord in a nested scale approach. A sensor array logging pH, O2, PAR, temperature and salinity was applied on spatial scales ranging from km-scale across the horizontal extension of the fjord, over 100 m scale vertically in the fjord, 10–100 m scale between subtidal habitats with and without kelp forests and between vegetated tidal pools and adjacent vegetated shores, to cm-m scale within kelp forests and mm-scale across boundary layers of macrophyte tissue. In addition, we assessed the temporal variability in pH on diurnal and seasonal scales. Based on pH-measurements combined with relationships between salinity, total alkalinity and dissolved inorganic carbon we also estimated variability of Ωarag. Results show variability in pH and Ωarag of up to 0.2–0.3 units at several scales, i.e. along the horizontal and vertical extension of the fjord, between seasons and on a diel basis in benthic habitats and within 1 m3 of kelp forest. Vegetated intertidal pools exhibited extreme diel pH variability of > 1.5 units and macrophyte boundary layers a pH-range of up to 0.8 units. Overall, Ωarag was favorable to calcification, and pelagic and benthic metabolism was an important driver of pH and Ωarag producing mosaics of variability from low levels in the dark to peak levels at high irradiance. We suggest that productive coastal environments may form niches of high pH in a future acidified Arctic Ocean.

Continue reading ‘Macroalgae contribute to nested mosaics of pH variability in a sub-Arctic fjord’

U.S. action needed on ocean acidification

Dr. Thomas Armstrong is the Deputy Secretary of the Arctic Monitoring and Assessment Programme and leads the Adaptation Actions for a Changing Arctic. He previously served in the Obama Whitehouse as the Executive Director of the U.S.Global Change Reaserch Program. This article originally appeared in The Circle 01.15.

The ocean regulates our climate and our weather and plays a fundamental role in maintaining Earth’s water, carbon and nutrient cycles. Since the start of the Industrial Revolution, human activities have upset the natural balance of nutrients in the ocean. Tom Armstrong warns changes in the oceanic carbon cycle are causing dramatic changes in the Arctic Ocean and need a strong response from the incoming chair of the Arctic Council.

The ocean has absorbed nearly one-third of the carbon dioxide (CO2) added to the atmosphere by humans from deforestation and the burning of fossil fuels. Because the ocean has absorbed so much CO2, greenhouse warming of the atmosphere is less severe. But, there is a critical downside: the dissolved CO2 increases the acidity of ocean water, threatening aquatic life and the livelihoods that depend on it. Without global action to limit CO2 emissions, this trend will continue.

Continue reading ‘U.S. action needed on ocean acidification’

Ocean acidification is topic of science presentation at Modesto Junior College

The Modesto Area Partners in Science (MAPS) will offer a presentation on “Ocean Acidification: The Other CO2 Problem” by Tessa Hill, U.C. Davis associate professor in Earth and Planetary Sciences.  The free public MAPS event will be held on Friday, April 10, at 7:30 p.m. in Sierra Hall 132 on the Modesto Junior College West Campus, 2201 Blue Gum Avenue in Modesto, and is intended for people over 12 years of age.

During her presentation Hill will explore the basics of ocean acidification and share research on its impact on marine ecosystems.

Continue reading ‘Ocean acidification is topic of science presentation at Modesto Junior College’

OA-ICC bibliographic database updated

An updated version of the OA-ICC bibliographic database is now available online.

The database contains nearly 2500 references and includes citations, abstracts and assigned keywords. Updates are made on a regular basis.

Continue reading ‘OA-ICC bibliographic database updated’

New England states following a model set by Maine to reduce ocean acidity

A group of state legislators believe the acidity will endanger multimillion dollar fishing industries if left unchecked.

A group of state legislators in New England wants to form a multistate pact to counter increasing ocean acidity along the East Coast, a problem they believe will endanger multimillion-dollar fishing industries if left unchecked.

The legislators’ effort faces numerous hurdles: They are in the early stages of fostering cooperation between many layers of government, hope to push for potentially expensive research and mitigation projects, and want to use state laws to tackle a problem scientists say is the product of global environmental trends.

Continue reading ‘New England states following a model set by Maine to reduce ocean acidity’

Another Voice: Increase in carbon dioxide threatens health of oceans

Most of the current concern about the ever-increasing concentration of carbon dioxide in the atmosphere has focused on global climate change. This is a serious problem, but carbon dioxide is also adversely affecting our oceans. Oceans cover 71 percent of the earth’s surface and, while they are unseen by most of us, they are critical to our well-being. The role that carbon dioxide plays in threatening them, however, receives scant attention.

Since the beginning of the Industrial Revolution in the late 18th century, mankind has pumped well over 500 billion tons of carbon dioxide into the atmosphere, raising its concentration there to 400 parts per million (ppm), higher than it has been in recorded history and nearly doubling its pre-industrial era concentration. Today we emit carbon dioxide so rapidly, over 38 billion tons per year according to CBS News, that its concentration may reach 500 ppm during this century.

Continue reading ‘Another Voice: Increase in carbon dioxide threatens health of oceans’

Senators: ocean acidification monitoring critical to nation’s $2.8B shellfish industry

In the letter to the Senate Appropriations Committee, Cantwell called for continued support of the National Oceanic and Atmospheric Administration’s (NOAA) Integrated Ocean Acidification Program and the Integrated Ocean Observing System (IOOS). Data from IOOS sensors and buoys along the nation’s coasts have helped shellfish hatcheries determine when to shield their stocks from corrosive sea water.

“Ocean acidification poses a serious threat to coastal economies across the United States,” the letter said. “We believe that worsening ocean acidification makes it incumbent on us to protect efforts that are helping maintain shellfish industries across the nation. We also support targeted investments in monitoring and research to increase our ocean acidification monitoring network, and provide critical data to communities that have been identified as high risk.”

Continue reading ‘Senators: ocean acidification monitoring critical to nation’s $2.8B shellfish industry’

Influence of ocean acidification on the complexation of iron and copper by organic ligands in estuarine waters

The uptake of anthropogenic atmospheric CO2 by the oceans causes a shift in the carbonate chemistry system which includes a lowering of pH; this process has been termed ocean acidification. Our understanding of the specific effects of ocean acidification on chemical speciation of trace metals, in particular on organic-metal interactions, is limited. In this study we have experimentally determined the effects of changing pH from 8.3 to 6.8 (on the NBS scale) on the speciation of iron and copper in estuarine waters. Our experimental results indicated that complexation of iron and copper would decrease and inorganic iron and copper concentrations increase, as pH decreased, although it was not possible to confidently quantify changes in speciation at lower pH due to constraints of the analytical technique. In addition to our experimental approach, we used a non-ideal competitive adsorption (NICA)- Donnan model to determine the chemical speciation of iron and copper as a function of pH. The NICA-Donnan model was optimised in order to produce similar metal binding characteristics to those observed in our sample across the pH range examined in our study. The model allowed for simultaneous modelling of solubility and organic complexation. Model results indicated that a decrease in iron and copper binding by organic matter at lower pH, coupled with increased solubility (for iron), resulted in a 3 fold increase in inorganic iron concentration and a 6 fold increase in inorganic copper concentration at pH of 7.41 compared to a pH of 8.18 (expressed on the total scale). This compared to a 10 fold increase in inorganic iron concentration, and a 5 fold increase in inorganic copper concentration, obtained at pH 8.18, when the dissolved organic carbon (DOC) concentration was halved. Variability in DOC might thus be expected to have a greater impact on metal speciation in seawater, than projected variability in pH resulting from increases in atmospheric CO2. Our study therefore suggests that increases in the concentrations of the more bioavailable inorganic iron and copper species in estuarine waters resulting from increased pCO2 are likely to occur, but that such changes will be moderate in magnitude.

Continue reading ‘Influence of ocean acidification on the complexation of iron and copper by organic ligands in estuarine waters’


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Ocean acidification in the IPCC AR5 WG II

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