Archive for 2012

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Ocean acidification and coral reefs Cmap

Published 20 September 2012 Science Closed

Authors: Katherine Jernigan, Steven Bateman, Daphne Hamilton

Theme: Ocean Acidification and Coral Reefs as related to Food Security and Eco-Tourism

Ocean acidification impacts people and economies through its effects on marine ecosystems. Our topic focuses on the impacts of acidification on coral reefs, and how this in turn affects humans through food security and economic situations. It shows how ecotourism, food security, and the degradation of coral reefs are all intertwined. Our theme does not include all the players that contribute to climate change and ocean acidification, though we will touch slightly on the general causes of ocean acidification.

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Carbon dioxide from water pollution, as well as air pollution, may adversely impact oceans

Published 20 September 2012 Media coverage , Science Closed

Carbon dioxide from water pollution, as well as air pollution, may adversely impact oceans

Carbon dioxide (CO2) released into the oceans as a result of water pollution by nutrients — a major source of this greenhouse gas that gets little public attention — is enhancing the unwanted changes in ocean acidity due to atmospheric increases in CO2. The changes may already be impacting commercial fish and shellfish populations, according to new data and model predictions published today in ACS’s journal, Environmental Science & Technology.

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NOAA announces grants to predict ocean acidification’s effects on commercial fisheries

Published 20 September 2012 Projects , Science Closed

As scientists continue to research ways in which the oceans are changing – and what these changes mean for fish populations, three new research projects will receive funding to examine the effects of ocean acidification on fisheries, and the coastal economies that depend upon them.

Ocean acidification occurs when the ocean absorbs carbon dioxide from the atmosphere, making it more acidic. Species as diverse as scallops and coral are vulnerable to ocean acidification, which can affect the growth of their shells and skeletons.

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Understanding ocean acidification: hands-on demos and activities

Published 20 September 2012 Media coverage Closed

This website presents hands-on demonstrations and experiments done at the Ocean Acidification workshop, July 2012. The site also includes presentations by scientists and educators, useful links, and an ocean pledge that explains on a personal level what you can do to reduce CO2 emissions.

The hands-on activities will help demonstrate and explore the effects of increasing carbon dioxide on the acidity of the ocean and learn about impacts an acidic ocean has on marine organisms, the ocean food web, and humans. You will also investigate the causes for increased ocean acidity and learn about ways to minimize your impact.

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Global calcite cycling constrained by sediment preservation controls

Published 19 September 2012 Science Closed
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We assess the global balance of calcite export through the water column and burial in sediments as it varies regionally. We first drive a comprehensive 1-D model for sediment calcite preservation with globally gridded field observations and satellite-based syntheses. We then reformulate this model into a simpler five-parameter box model, and combine it with algorithms for surface calcite export and water column dissolution for a single expression for the vertical calcite balance. The resulting metamodel is optimized to fit the observed distributions of calcite burial flux. We quantify the degree to which calcite export, saturation state, organic carbon respiration, and lithogenic sedimentation modulate the burial of calcite. We find that 46% of burial and 88% of dissolution occurs in sediments overlain by undersaturated bottom water with sediment calcite burial strongly modulated by surface export. Relative to organic carbon export, we find surface calcite export skewed geographically toward relatively warm, oligotrophic areas dominated by small, prokaryotic phytoplankton. We assess century-scale projected impacts of warming and acidification on calcite export, finding high sensitive to inferred saturation state controls. With respect to long-term glacial cycling, our analysis supports the hypothesis that strong glacial abyssal stratification drives the lysocline toward much closer correspondence with the saturation horizon. Our analysis suggests that, over the transition from interglacial to glacial ocean, a resulting ∼0.029 PgC a−1 decrease in deep Atlantic, Indian and Southern Ocean calcite burial leads to slow increase in ocean alkalinity until Pacific mid-depth calcite burial increases to compensate.

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Purposeful Instruction: mixing up the “I,” “We,” and “You”

Published 19 September 2012 Science Closed

This article discusses the flexible nature of the gradual release of responsibility (GRR) as a frame for inquiry-based science instruction. Given the mandate for the use of text-supported learning (Common Core Standards), the GRR can be used to allow students to learn as scientists as they collaboratively develop testable questions and experiments that direct them to look at real-world issues. Through various configurations of modeling, guided instruction, collaborative efforts, and independent work, teachers are able establish an environment where investigative inquiry learning thrives.

Would you vote for a toilet-to-tap initiative? Although the idea sounds revolting, you know how to build knowledge to answer this question. Students must be taught these same inquiry skills.

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The early life history of the clam Macoma balthica in a high CO2 world

Published 19 September 2012 Science Closed
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This study investigated the effects of experimentally manipulated seawater carbonate chemistry on several early life history processes of the Baltic tellin (Macoma balthica), a widely distributed bivalve that plays a critical role in the functioning of many coastal habitats. We demonstrate that ocean acidification significantly depresses fertilization, embryogenesis, larval development and survival during the pelagic phase. Fertilization and the formation of a D-shaped shell during embryogenesis were severely diminished: successful fertilization was reduced by 11% at a 0.6 pH unit decrease from present (pH 8.1) conditions, while hatching success was depressed by 34 and 87%, respectively at a 0.3 and 0.6 pH unit decrease. Under acidified conditions, larvae were still able to develop a shell during the post-embryonic phase, but higher larval mortality rates indicate that fewer larvae may metamorphose and settle in an acidified ocean. The cumulative impact of decreasing seawater pH on fertilization, embryogenesis and survival to the benthic stage is estimated to reduce the number of competent settlers by 38% for a 0.3 pH unit decrease, and by 89% for a 0.6 pH unit decrease from present conditions. Additionally, slower growth rates and a delayed metamorphosis at a smaller size were indicative for larvae developed under acidified conditions. This may further decline the recruit population size due to a longer subjection to perturbations, such as predation, during the pelagic phase. In general, early life history processes were most severely compromised at ~pH 7.5, which corresponds to seawater undersaturated with respect to aragonite. Since recent models predict a comparable decrease in pH in coastal waters in the near future, this study indicates that future populations of Macoma balthica are likely to decline as a consequence of ongoing ocean acidification.

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An alternative approach for addressing CO2-driven ocean acidification

Published 19 September 2012 Science Closed
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The oceans have absorbed over twenty-five percent of the anthropogenic carbon dioxide (“CO2”) released to the atmosphere since pre-industrial times.1 As a result, naturally alkaline oceans are becoming more acidic.2 The projected increase in CO2 emissions absorbed by the oceans will cause changes in water chemistry that may affect “biodiversity, trophic interactions, and other ecosystem processes.”3 Elevated CO2 will lower the availability of carbonate ions, which calcifying organisms need to create their shells and skeletons.4 In the case of corals, it is likely to induce bleaching.5 High CO2 concentrations will reduce larval fish survival,6 as it impairs their ability to detect predators and find adequate habitat.7 It is clear that “[a]cidification impacts processes so fundamental [that it] could have far-reaching consequences for the oceans of the future and the millions of people that depend on its food and other resources for their livelihoods.”8

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A subseafloor carbonate factory across the Triassic-Jurassic transition

Published 19 September 2012 Science Closed
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Triassic-Jurassic (T-J) boundary successions record a paucity of carbonate in association with the mass extinction. Here we demonstrate that three globally disparate T-J sections contain volumetrically important early diagenetic carbonate, i.e., carbonate formed soon after deposition of the sediment but commonly ignored as secondary, that contains information about the extinction and may constitute a previously unrecognized pathway in the carbon cycle. Petrographic analyses of unusual carbonate fans from three sites reveal that they grew just below the sediment-water interface, nearly concomitant with primary sediment deposition. Thus, the shallow subseafloor can be a carbonate sink of unknown size, and may be a predictable consequence of ocean acidification where carbonate precipitation first returns within the sediment before recovering in the water column.

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Constraints on ocean acidification associated with rapid and massive carbon Injections of the early Paleogene: the geological record at Ocean Drilling Program Site 1215, Equatorial Pacific Ocean

Published 19 September 2012 Science Closed
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Massive amounts of 13C-depleted carbon rapidly entered the ocean more than once during the early Paleogene, providing a geological framework for understanding future perturbations in carbon cycling, including ocean acidification. To assess the number of events and their impact on deep-sea carbonate accumulation, I have studied carbonate ooze units of the upper Paleocene–lower Eocene, which were deposited on a subsiding flank of the East Pacific Rise (ODP Site 1215). From this record several proxies were used to ascertain changes in carbonate dissolution: carbonate content, foraminiferal test fragmentation, and planktic/benthic foraminiferal ratio. Based on these analyses, 1 observe that carbonate preservation generally increased from the late Paleocene (56 Ma) through the early Eocene (51.5 Ma), after which it became poor to negligible. This trend was punctuated by four short-term intervals characterized by carbonate dissolution and pronounced negative d18O and d13C excursions. It is inferred that these were anomalously warm periods (hyperthermals) caused by massive and relative fast 13C-depleted carbon injections. These correspond to the PETM (∼55.5 Ma), H1/ETM-2 (∼53.7 Ma), I1 (∼53.2 Ma), and K/X (∼52.5 Ma) events.

I also calculated carbonate, planktic, and benthic foraminiferal mass accumulation rates for the Site 1215. These were used to comprehensively examine the history of carbonate accumulation in the equatorial Pacific Ocean throughout the early Paleogene. I deduce that in the long-term (>105 yr) the lysocline and calcite compensation depth (CCD) generally deepened between 55.4 and 51.5 Ma; but rapidly (≤105 yr) shoaled and subsequently overcompensated during and after the four intervals of massive carbon injection.

Planktic foraminiferal assemblages found in the record of Site 1215 follow a predicted pattern for selective dissolution. Species of Acarinina are preferentially preserved over Morozovella, which are preferentially preserved over Subbotina, Igorina and Globanomalina. A tiny and previously overlooked species, Praetenuitella antica n.sp, is formally described in this manuscript. This species is also resistant to dissolution.

The findings of this study provide firm constraints to model the short and long-term carbon cycle dynamics during the early Paleogene.

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Osteoporosis in the world’s oceans: bioeroding sponges are threatening coral reefs

Published 19 September 2012 Media coverage , Science Closed

Frankfurt, 19.09.2012. Due to the massive production of the greenhouse gas carbon dioxide our oceans are becoming increasingly acidic. Scientists of Senckenberg am Meer in Wilhelmshaven studied the consequences of ocean acidification on sponges that bore into calcareous materials such as coral skeletons. Results show that these sponges will profit from global changes, while coral reefs are threatened in their survival. The study was published today in the scientific journal PLoS ONE.

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Ocean acidification accelerates reef bioerosion

Published 19 September 2012 Science Closed
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In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO2) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process – biologically induced carbonate dissolution via bioerosion – has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO2 world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia’s Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO2 confirms a significant enforcement of the sponges’ bioerosion capacity with increasing pCO2 under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation.

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Contrasting responses of DMS and DMSP to ocean acidification in Arctic waters

Published 19 September 2012 Science Closed
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Increasing atmospheric CO2 is decreasing ocean pH most rapidly in colder regions such as the Arctic. As a component of the EPOCA pelagic mesocosm experiment off Spitzbergen in 2010, we examined the consequences of decreased pH and increased pCO2 on the concentrations of dimethylsulphide (DMS). DMS is an important reactant and contributor to aerosol formation and growth in the Arctic troposphere. In the nine mesocosms with initial pH 8.3 to 7.5, equivalent to pCO2 of 180 to 1420 μatm, highly significant but inverse responses to acidity (hydrogen ion concentration [H+]) occurred following nutrient addition. Compared to ambient [H+], average concentrations of DMS during the most representative phase of the 30 d experiment were reduced by approximately 60% at the highest [H+] and by 35% at [H+] equivalent to 750 μatm pCO2, as predicted for 2100. In contrast, concentrations of dimethylsulphoniopropionate (DMSP), the precursor of DMS, were elevated by approximately 50% at the highest [H+] and by 30% at [H+] corresponding to 750 μatm pCO2. Measurements of the specific rate of synthesis of DMSP by phytoplankton indicate increased production at high [H+], in parallel to rates of inorganic carbon fixation. The elevated DMSP production at high [H+] was largely a consequence of increased dinoflagellate biomass and in particular, the increased abundance of the species Heterocapsa rotundata. We discuss both phytoplankton and bacterial processes that may explain the reduced ratios of DMS:DMSPt at higher [H+]. The experimental design of eight treatment levels provides comparatively robust empirical relationships of DMS and DMSP concentration, DMSP production and dinoflagellate biomass versus [H+] in Arctic waters.

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Primary production and respiration of hypersaline microbial mats as a response for high and low CO2 availability

Published 19 September 2012 Science Closed
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Here we report a time series of experiments performed in a microcosm to test the response of hypersaline microbial mats to diverse atmospheric CO2 conditions. Different from most part of the literature, our study used a sample chamber were carbon dioxide concentration was controlled. Our aim was to test the effect of different atmospheric CO2 conditions in benthic gross and net primary production, and respiration. This study showed for the first time to our knowledge absolute carbon limitation in a microbial mat. Oxygen concentration profile varied from a flattened shape to almost linear when atmospheric CO2 at the chamber reached 0 ppm, with NPP reaching 0 nmol cm−3 s−1 throughout most part of the profile. In this conditions sediment community respiration represented 100% of GPP. Extreme close coupling between primary production and respiration in microbial mats can be even self-sustainable in environments with temporally no atmospheric CO2 available. When submitted to even high CO2 concentrations (550 ppm), our sample showed a characteristic shape that indicate limitation composed by a more rectilinear oxygen profile, and NPP peaks mainly restricted to deeper layers. Therefore, we suggest that phototrophic communities in aquatic shallow ecosystems can be carbon limited. This limitation could be common especially in ecosystems submitted to variable water depth conditions, like coastal lagoons and intertidal sediments.

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PhD opportunity: Vulnerability of marine invertebrates living along latitudinal and depth gradients to complex global environmental changes (update)

Published 18 September 2012 Jobs , Science Closed

FACULTY OF SCIENCE AND TECHNOLOGY, SCHOOL OF MARINE SCIENCE AND ENGINEERING
Marine Institute Funded PhD Research Studentship

Vulnerability of marine invertebrates living along latitudinal and depth gradients to complex global environmental changes

Supervisors
Dr Piero Calosi, Plymouth University
Professor Paul Shaw, University of Aberystwyth
Dr William Cheung, University of British Columbia

Project Description
As a result of on-going rapid global changes (warming, acidification, de-oxygenation) some areas of our oceans are becoming inhospitable for some marine organisms. In addition as marine animals are in general adapted to the conditions they live in, different populations and species living along environmental gradients may possess different levels of vulnerability to future environmental changes. Despite its paramount importance however, the physiological, ecological and genetic mechanisms which will define taxa vulnerability to complex environmental changes are still poorly understood for marine organisms. As a consequence, our capacity to predict ability of taxa to retain their range edges of distribution and size of their latitudinal range of geographical extension in the face of the global change is limited. We propose a challenging multidisciplinary PhD project which aims to explore the evolutionary macrophysiology of marine organisms within the context of global change. This PhD project will mainly be based at Plymouth University although the candidate will be expected to work for substantial periods of time both at the Population Genetics and Genomics Laboratory of Professor Shaw and at the Changing Ocean Research Unit of Dr Cheung, as well as at sea to participate to collection trips and scientific cruises. Ultimately the physiological, ecological and genetic data collected will be used to build statistical models, and also to parameterise Dr Cheung’s existing Dynamic Bioclimate Envelope Model.

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International conference on Arctic Ocean acidification

Published 18 September 2012 Meetings , Science Closed

The Arctic Ocean is rapidly accumulating carbon dioxide resulting in a decline in pH. Marine ecosystems and biodiversity will change, creating new economic, social and policy challenges.

When
May 06, 2013 08:00 AM to
May 08, 2013 06:00 PM

Where
Bergen, Norway

Contact
Inger Utne: +47 22 95 83 40

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As global warming creates climate changes, our oceans are in danger

Published 18 September 2012 Media coverage Closed

Calcium carbonate is important for many marine animals. This chalky substance forms the ridged spicules that scaffold some sponge species, the limy deposits that build coral reefs, the protective shells of clams and snails, and the spiny-skins of sea urchins and starfish. All these organisms are important constituents of marine ecosystems, often forming the basal trophic levels that enable food-webs to function. However, there are studies that suggest increased levels of atmospheric carbon dioxide could alter the chemistry of the ocean, which could affect how marine organisms deposit calcium carbonate into their structures. This process, known as ocean acidification, could impact marine food-webs and the human communities who depend on the sea for supplementing diets and incomes.

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Total alkalinity estimation using MLR and neural network techniques

Published 18 September 2012 Science Closed
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During the last decade, two important collections of carbon relevant hydrochemical data have become available: GLODAP and CARINA. These collections comprise a synthesis of bottle data for all ocean depths from many cruises collected over several decades. For a majority of the cruises at least two carbon parameters were measured. However, for a large number of stations, samples or even cruises, the carbonate system is under-determined (i.e., only one or no carbonate parameter was measured) resulting in data gaps for the carbonate system in these collections. A method for filling these gaps would be very useful, as it would help with estimations of the anthropogenic carbon (Cant) content or quantification of oceanic acidification. The aim of this work is to apply and describe, a 3D moving window multilinear regression algorithm (MLR) to fill gaps in total alkalinity (AT) of the CARINA and GLODAP data collections for the Atlantic. In addition to filling data gaps, the estimated AT values derived from the MLR are useful in quality control of the measurements of the carbonate system, as they can aid in the identification of outliers. For comparison, a neural network algorithm able to perform non-linear predictions was also designed. The goal here was to design an alternative approach to accomplish the same task of filling AT gaps. Both methods return internally consistent results, thereby giving confidence in our approach.

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Temporal biomass dynamics of an Arctic plankton bloom in response to increasing levels of atmospheric carbon dioxide

Published 17 September 2012 Science Closed
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Ocean acidification and carbonation, driven by anthropogenic emissions of carbon dioxide (CO2), have been shown to affect a variety of marine organisms and are likely to change ecosystem functioning. High latitudes, especially the Arctic, will be the first to encounter profound changes in carbonate chemistry speciation at a large scale, namely the under-saturation of surface waters with respect to aragonite, a calcium carbonate polymorph produced by several organisms in this region. During a CO2 perturbation study in 2010, in the framework of the EU-funded project EPOCA, the temporal dynamics of a plankton bloom was followed in nine mesocosms, manipulated for CO2 levels ranging initially from about 185 to 1420 μatm. Dissolved inorganic nutrients were added halfway through the experiment. Autotrophic biomass, as identified by chlorophyll a standing stocks (Chl a), peaked three times in all mesocosms. However, while absolute Chl a concentrations were similar in all mesocosms during the first phase of the experiment, higher autotrophic biomass was measured at high in comparison to low CO2 during the second phase, right after dissolved inorganic nutrient addition. This trend then reversed in the third phase. There were several statistically significant CO2 effects on a variety of parameters measured in certain phases, such as nutrient utilization, standing stocks of particulate organic matter, and phytoplankton species composition. Interestingly, CO2 effects developed slowly but steadily, becoming more and more statistically significant with time. The observed CO2 related shifts in nutrient flow into different phytoplankton groups (mainly diatoms, dinoflagellates, prasinophytes and haptophytes) could have consequences for future organic matter flow to higher trophic levels and export production, with consequences for ecosystem productivity and atmospheric CO2.

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Arctic microbial community dynamics influenced by elevated CO2 levels

Published 17 September 2012 Science Closed
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The Arctic Ocean ecosystem is particular vulnerable for ocean acidification (OA) related alterations due to the relatively high CO2 solubility and low carbonate saturation states of its cold surface waters. Thus far, however, there is only little known about the consequences of OA on the base of the food web. In a mesocosm CO2-enrichment experiment (overall CO2 levels ranged from ∼180 to 1100 μatm) in the Kongsfjord off Svalbard, we studied the consequences of OA on a natural pelagic microbial community. The most prominent finding of our study is the profound effect of OA on the composition and growth of the Arctic phytoplankton community, i.e. the picoeukaryotic photoautotrophs and to a lesser extent the nanophytoplankton prospered. A shift towards the smallest phytoplankton as a result of OA will have direct consequences for the structure and functioning of the pelagic food web and thus for the biogeochemical cycles. Furthermore, the dominant pico- and nanophytoplankton groups were found prone to viral lysis, thereby shunting the carbon accumulation in living organisms into the dissolved pools of organic carbon and subsequently affecting the efficiency of the biological pump in these Arctic waters.

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