Archive for January, 2017

Tracing the dynamics of dissolved organic matter in marine systems exposed to natural and experimental perturbations

In the coming decades, global warming will affect the biogeochemical cycles evolution, particularly the carbon cycle. In this context, it is necessary to gain knowledge on the Earth natural mechanisms to relieve the atmosphere of the greenhouse gases excess. The “biological pump” is one of the main mechanisms employed by the oceans to “sequester” the CO2 accumulated in the atmosphere. Thereby, the organic carbon produced by the biological activity is transferred from surface to deep waters where part of this pool is accumulated in the seafloor. Another mechanism involving the accumulation of carbon in the ocean, called the “microbial carbon pump” (MCP), has been described recently. It is composed by an intricate set of microbial processes that enable the formation of highly recalcitrant dissolved material and therefore facilitate the accumulation of carbon in the deep waters. The oceans store about 660 Pg C in the form of dissolved organic matter (DOM), a quantity comparable to the atmospheric CO2. Understanding the processes that control the dynamics, recycling and exportation of the DOM is crucial to evaluate the oceans capability to gather the excess of atmospheric CO2. On its course down throughout the water column, microorganisms degraded the DOM produced at the surface layers. Concentrations decrease from ~90 µmol C L-1 down to 40-50 µmol C L-1, values homogeneously distributed in the deep oceans throughout the planet. The fact that below 1000 m and deeper the DOM is degraded at lower speed is still unknown, and the processes that can affect this DOM degradation have been studied in this thesis. In this regard, we performed experiments with deep Atlantic Ocean microbial communities. These communities were exposed to DOM of different quality. The results revealed that the presence of humic-like allocthonous compounds favored the generation of new humic-like compounds in situ. Consequently, we proved that the composition of the DOM that reach the deep ocean conditions its ease-to-degrade nature. In this thesis we also evaluated the effect of global change (acidification and eutrophication) on the quality of the DOM. With this purpose in mind, we developed mesocosms experiments in tanks of 200 L in which we enclosed coastal planktonic communities from the NW Mediterranean Sea. The planktonic populations were exposed to different treatments of pH and eutrophication (addition of inorganic nutrients). The results of these experiments demonstrated that low pH levels favored the increase of the planktonic organisms’ growth rates, while the input of nutrients promoted the transformation to complex DOM. Finally, a monthly monitoring sampling of several biogeochemical variables was carried out at the Estartit Oceanographic Station (EOS). One of the principal aims consisted in identify the DOM sources and its inter-annual variability. The results revealed the importance of the winds in transporting oceanic DOM inputs to the system, which contrasted with previous results observed in nearby sampling stations (e.g. Blanes Bay, Bay of Banyuls-sur-mer), where the major DOM contributions were terrestrial inputs.

Continue reading ‘Tracing the dynamics of dissolved organic matter in marine systems exposed to natural and experimental perturbations’

The adaptive potential of early life-stage Fucus vesiculosus under multifactorial environmental change

Multiple global and local stressors threaten populations of the bladderwrack Fucus vesiculosus (Phaeophyceae). Baltic F. vesiculosus populations presumably have a lower genetic diversity compared to other populations. I investigated the adaptive potential under multifactorial environmental change in F. vesiculosus germlings. Effects of warming and acidification were crossed during one year at the two levels “present” and “future” (according to the year 2110) at the “Kiel Outdoor Benthocosms” by applying delta-treatments. Effects of warming varied with season while acidification showed generally weak effects. The two factors “ocean acidification and warming” (OAW) and nutrients were crossed showing that nutrient enrichment mitigated heat stress. Germlings previously treated under the OAW x nutrient experiment were subsequently exposed to a simulated hypoxic upwelling. Sensitivity to hypoxia was enhanced by the previous OAW conditions. Difference in the performance of genetically different sibling groups and diversity level were observed indicating an increased adaptive potential at higher genetic diversity. Different sibling groups were analysed under multiple factors to test correlations of genotypic sensitivities. Sensitivity towards warming, acidification and nutrient enrichment correlated positively while sensitivities towards OAW and hypoxia showed a negative correlation demonstrating that genotypes previously selected under OAW are sensitive to hypoxic upwelling. In a literature review, responses of marine organisms to climate change were analysed through different levels of biological organisation showing that climate change has different effects on each single level of biological organisation. This study highlights that global change research requires an upscaling approach with regard to multiple factors, seasons, natural fluctuations, different developmental stages and levels of biological organisation in the light of the adaptive potential.

Continue reading ‘The adaptive potential of early life-stage Fucus vesiculosus under multifactorial environmental change’

Regional Workshop on the Management of Marine Resources

A three-day Regional Workshop on measures to manage marine resources commenced on January 24 at The Jamaica Pegasus hotel in New Kingston.

It is being hosted by the British High Commission, under the Caribbean Commonwealth Marine Economies programme, which involves a £5.6 million package of measures to help small island countries reduce poverty by preserving their marine environments, and making the best use of their marine resources.

A further aim of the programme is to support the sustainable growth of Commonwealth Small Island Developing States (SIDS) within the Caribbean, Pacific and Indian Ocean regions. The programme will last for one year initially, with potential for continuation.

Issues being addressed under the programme are: climate change, ocean acidification, pollution, overfishing, and loss of habitats. These threaten subsistence livelihoods, commercial fishing and food supply.

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Exploring the “Sharkcano”: biogeochemical observations of the Kavachi submarine volcano (Solomon Islands)

An expedition to the Kavachi submarine volcano (Solomon Islands) in January 2015 was serendipitously timed with a rare lull in volcanic activity that permitted access to the inside of Kavachi’s active crater and its flanks. The isolated location of Kavachi and its explosive behavior normally restrict scientific access to the volcano’s summit, limiting previous observational efforts to surface imagery and peripheral water-column data. This article presents medium-resolution bathymetry of the main peak along with benthic imagery, biological observations of multiple trophic levels living inside the active crater, petrological and geochemical analysis of samples from the crater rim, measurements of water temperature and gas flux over the summit, and descriptions of the hydrothermal plume structure. A second peak was identified to the southwest of the main summit and displayed evidence of diffuse-flow venting. Microbial samples collected from the summit indicate chemosynthetic populations dominated by sulfur-reducing ε-proteobacteria. Populations of gelatinous animals, small fish, and sharks were observed inside the active crater, raising new questions about the ecology of active submarine volcanoes and the extreme environments in which large marine animals can exist.

Continue reading ‘Exploring the “Sharkcano”: biogeochemical observations of the Kavachi submarine volcano (Solomon Islands)’

Episode of intense chemical weathering during the termination of the 635 Ma Marinoan glaciation

Cryogenian (∼720–635 Ma) global glaciations (the snowball Earth) represent the most extreme ice ages in Earth’s history. The termination of these snowball Earth glaciations is marked by the global precipitation of cap carbonates, which are interpreted to have been driven by intense chemical weathering on continents. However, direct geochemical evidence for the intense chemical weathering in the aftermath of snowball glaciations is lacking. Here, we report Mg isotopic data from the terminal Cryogenian or Marinoan-age Nantuo Formation and the overlying cap carbonate of the basal Doushantuo Formation in South China. A positive excursion of extremely high δ26Mg values (+0.56 to +0.95)—indicative of an episode of intense chemical weathering—occurs in the top Nantuo Formation, whereas the siliciclastic component of the overlying Doushantuo cap carbonate has significantly lower δ26Mg values (<+0.40), suggesting moderate to low intensity of chemical weathering during cap carbonate deposition. These observations suggest that cap carbonate deposition postdates the climax of chemical weathering, probably because of the suppression of carbonate precipitation in an acidified ocean when atmospheric CO2 concentration was high. Cap carbonate deposition did not occur until chemical weathering had consumed substantial amounts of atmospheric CO2 and accumulated high levels of oceanic alkalinity. Our finding confirms intense chemical weathering at the onset of deglaciation but indicates that the maximum weathering predated cap carbonate deposition.

Continue reading ‘Episode of intense chemical weathering during the termination of the 635 Ma Marinoan glaciation’

Using demonstrations involving combustion and acid–base chemistry to show hydration of carbon dioxide, sulfur dioxide, and magnesium oxide and their relevance for environmental climate science

The nature of acidic and basic (alkaline) oxides can be easily illustrated via a series of three straightforward classroom demonstrations for high school and general chemistry courses. Properties of carbon dioxide, sulfur dioxide, and magnesium oxide are revealed inexpensively and safely. Additionally, the very different kinetics of hydration of SO2 (rapid) and CO2 (slow) are evident. The pH changes observed by use of universal indicator provide striking visual evidence that makes the concepts of acidic and basic oxides less abstract and more concrete than verbal or written descriptions alone. By using the MgO solution for the SO2 hydration reaction, one can mimic environmental interactions that lead to the neutralization of alkaline and acidic species. Interestingly, the SO2 and CO2 demonstrations can easily be adapted to environmental chemistry courses and especially the very relevant realm of climate change science. The difference in hydration rates explains why CO2 is a greenhouse gas, but SO2 is not listed as one. Variations of the CO2 hydration demonstration reveal the sensitivity of oceans to acidification by dissolved CO2 and the relationship of fossil fuel combustion to ocean acidification.

Continue reading ‘Using demonstrations involving combustion and acid–base chemistry to show hydration of carbon dioxide, sulfur dioxide, and magnesium oxide and their relevance for environmental climate science’

Role of potassium and pH on the initiation of sperm motility in the European eel

The role of potassium from the seminal plasma and/or the activation media was examined by selectively removing K+ from this media, and by testing the use of K+ channel inhibitors and a K-ionophore. Sperm motility was measured using a CASA system, intracellular K+ and pH were measured by flow cytometry, and sperm head area was measured by ASMA: Automated Sperm Morphometry Analyses. Sperm motility was notably inhibited by the removal of K+ from the seminal plasma and by treatment with the K+ ionophore valinomycin. This therefore indicates that a reduction of K+ levels in the quiescent stage inhibits further motility. The normal decrease in sperm head area induced by seawater activation was altered by the removal of K+ from the seminal plasma, and an increase in the pHi in the quiescent stage was also induced. Intracellular pH (pHi) was quantitatively measured for the first time in European eel spermatozoa, being 7.2 in the quiescent stage and 7.1 post-activation. Intracellular and external pH levels influenced sperm motility both in the quiescent stage and at activation. The alkalinization of the pHi (by NH4Cl) inhibited sperm motility activation, while acidification (by Na-acetate) did not have any effect. Our results indicate that a pH gradient between the sperm cell and the seminal plasma is necessary for sperm motility activation. The presence of the ion K+ in the seminal plasma (or in the extender medium) is necessary in order to maintain sperm volume, intracellular pH and sperm motility.

Continue reading ‘Role of potassium and pH on the initiation of sperm motility in the European eel’

Research on the sensitivity of the marine industry to climate change

Marine economic activities are mostly carried out in coastal zones with the most fragile ecological environment. (…)

(…) this paper develops an evaluation system for sensitivity coefficient by by quantifying specific indicators and finally confirms the sensitivity of different marine industries to climate change. The evaluation reveals that the salt marine industry is the most vulnerable to climate change followed by marine transportation, fishery, mining, shipbuilding, and coastal tourism. (…)

Continue reading ‘Research on the sensitivity of the marine industry to climate change’

State Department of Environmental Conservation releases final Ocean Action Plan for New York (excerpts)

New York State Department of Environmental Conservation (DEC) Commissioner Basil Seggos today announced the release of the State’s final Ocean Action Plan.

Albany, NY – January 23, 2017 – New York State Department of Environmental Conservation (DEC) Commissioner Basil Seggos today announced the release of the State’s final Ocean Action Plan, the first-ever comprehensive 10-year blueprint to guide the protection and conservation of New York’s ocean resources from environmental threats such as ocean acidification due to climate change. The plan was developed with input from a variety of state agencies, as well as ocean-related advocacy and industry organizations. (…)

The Ocean Action Plan identifies 61 actions that address plan goals with actionable steps that need to be undertaken over the next decade using state funds, as well as leveraging related federal, conservation organization, and academic resources. (…)

The Ocean Action Plan also identifies the need for further evaluation of ocean acidification in state waters, including developing a cooperative marine research program to improve New York’s understanding of the factors, such as ocean acidification, potentially affecting recruitment success and long-term sustainability of fisheries. In December, New York joined the International Alliance to Combat Ocean Acidification, a network of governments and organizations responding to threats from ocean acidification. In November, Governor Andrew M. Cuomo signed legislation to establish the New York State Ocean Acidification Task Force to employ the best available science to develop an early assessment of impacts, identify adaptive measures, and strengthen the state’s regulatory response to this emerging threat.

Continue reading ‘State Department of Environmental Conservation releases final Ocean Action Plan for New York (excerpts)’

An aposymbiotic primary coral polyp counteracts acidification by active pH regulation

Corals build their skeletons using extracellular calcifying fluid located in the tissue–skeleton interface. However, the mechanism by which corals control the transport of calcium and other ions from seawater and the mechanism of constant alkalization of calcifying fluid are largely unknown. To address these questions, we performed direct pH imaging at calcification sites (subcalicoblastic medium, SCM) to visualize active pH upregulation in live aposymbiotic primary coral polyps treated with HCl-acidified seawater. Active alkalization was observed in all individuals using vital staining method while the movement of HPTS and Alexa Fluor to SCM suggests that certain ions such as H+ could diffuse via a paracellular pathway to SCM. Among them, we discovered acid-induced oscillations in the pH of SCM (pHSCM), observed in 24% of polyps examined. In addition, we discovered acid-induced pH up-regulation waves in 21% of polyps examined, which propagated among SCMs after exposure to acidified seawater. Our results showed that corals can regulate pHSCM more dynamically than was previously believed. These observations will have important implications for determining how corals regulate pHSCM during calcification. We propose that corals can sense ambient seawater pH via their innate pH-sensitive systems and regulate pHSCM using several unknown pH-regulating ion transporters that coordinate with multicellular signaling occurring in coral tissue.

Continue reading ‘An aposymbiotic primary coral polyp counteracts acidification by active pH regulation’

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Ocean acidification in the IPCC AR5 WG II

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