Climate change mitigation effects: How do potential CO2 leaks from a sub-seabed storage site in the Norwegian Sea affect Astarte sp. bivalves?

Carbon capture and storage (CCS) is one of the most promising mitigation strategies for reducing the emissions of carbon dioxide (CO2) to the atmosphere and may substantially help to decelerate global warming. There is an increasing demand for CCS sites. Nevertheless, there is a lack of knowledge of the environmental risk associated with potential leakage of CO2 from the storage sites; and even more, what happens when the seepage stops. Can the environment return to the initial equilibrium? Potential effects on native macrofauna were studied under a scenario of a 50-day CO2 leakage, and the subsequent leak closure. To accomplish the objective, Trondheim Fjord sediments and clams were exposed to an acidified environment (pH 6.9) at 29 atm for 7 weeks followed by a 14-day recovery at normal seawater conditions (pH 8.0, 29 atm). Growth and survival of clams exposed to pressure (29 atm) and reduced pH (6.9) did not significantly differ from control clams kept at 1 atm in natural seawater. Furthermore, bioaccumulation of elements in the soft tissue of clams did not register significant variations for most of the analysed elements (Cd, Cr, Pb, and Ti), while other elements (As, Cu, Fe, Ni) had decreasing concentrations in tissues under acidified conditions in contrast to Na and Mg, which registered an uptake (Ku) of 111 and 9.92 μg g−1dw d−1, respectively. This Ku may be altered due to the stress induced by acidification; and the element concentration being released from sediments was not highly affected at that pH. Therefore, a 1 unit drop in pH at the seafloor for several weeks does not appear to pose a risk for the clams.acceptedVersio

Towards Text Mining in Climate Science:Extraction of Quantitative Variables and their Relations

This paper addresses text mining in the cross-disciplinary fields of climate science, marine science and environmental science. It is motivated by the desire for literature-based knowledge discovery from scientific publications. The particular goal is to automatically extract relations between quantitative variables from raw text. This results in rules of the form “If variable X increases, than variable Y decreases”. As a first step in this direction, an annotation scheme is proposed to capture the events of interest – those of change, cause, correlation and feedback – and the entities involved in them, quantitative variables. Its purpose is to serve as an intermediary step in the process of rule extraction. It is shown that the desired rules can indeed be automatically extracted from annotated text. A number of open challenges are discussed, including automatic annotation, normalisation of variables, reasoning with rules in combination with domain knowledge and the need for meta-knowledge regarding context of use

Iron cycling in a mesocosm experiment in a north Patagonian fjord: Potential effect of ammonium addition by salmon aquaculture

Salmon aquaculture in Chile has been a rapidly growing industry, generating increasing inputs of organic matter and inorganic nutrients into the ecosystem. We studied the potential impacts of ammonium input by this industry on the cycling of iron (Fe) in a Chilean fjord. The distribution of different Fe fractions at varying ammonium concentrations was monitored in a twenty-two day mesocosm experiment. The setup involved brackish water and seawater; each had a control and four ammonium concentrations. Measurements were performed for total (TFeCh) and dissolved (DFeCh) chelex labile Fe fractions, and particulate Fe (PFe). Results for both brackish and seawater showed similar trends but differences in magnitude. Over time, DFeCh decreased with increasing ammonium concentration, while TFeCh showed up to a three-fold increase positively correlated with ammonium addition, chlorophyll and particulate organic carbon. Overall, PFe values increased over time with 37%–89% of this fraction estimated to be of lithogenic origin. When normalized to particulate organic carbon and chlorophyll, PFe was negatively correlated with ammonium showing an exponential decrease. The PFe measured in the 20–140 μm fraction, showed a hyperbolic relationship with particulate phosphorus, suggesting a change in the ratio for these elements in this size fraction. The increase and dominance of diatoms over time in both water types, together with the observed PFe trend, suggest that large phytoplankton potentially act as the main carrier phase of potential scavenged Fe via the available surfaces of sinking cells. Positive correlations between changes in TFeCh and changes in chlorophyll and particulate organic carbon suggest a biological role in controlling the particulate labile Fe fraction, hence resulting in a potential increase of bioavailable Fe. Increasing ammonium addition in the fjords of Chile caused by salmon aquaculture may affect the phytoplankton assemblage composition and therefore the PFe to organic carbon ratio. Possible changes in biogeochemical Fe cycling may result from nutrient enhanced diatom-dominated blooms acting as more efficient vectors for downward export of organic matter

Towards Text Mining in Climate Science:Extraction of Quantitative Variables and their Relations

This paper addresses text mining in the cross-disciplinary fields of climate science, marine science and environmental science. It is motivated by the desire for literature-based knowledge discovery from scientific publications. The particular goal is to automatically extract relations between quantitative variables from raw text. This results in rules of the form “If variable X increases, than variable Y decreases”. As a first step in this direction, an annotation scheme is proposed to capture the events of interest – those of change, cause, correlation and feedback – and the entities involved in them, quantitative variables. Its purpose is to serve as an intermediary step in the process of rule extraction. It is shown that the desired rules can indeed be automatically extracted from annotated text. A number of open challenges are discussed, including automatic annotation, normalisation of variables, reasoning with rules in combination with domain knowledge and the need for meta-knowledge regarding context of use

Responses in the bacterial community structure to waste nutrients from aquaculture: an in situ microcosm experiment in a Chilean fjord

Chilean salmon farms release inorganic nutrients excreted by the fish into the surrounding water in Patagonian fjords. The objective of this experiment from the Comau Fjord (42.2° S) in southern Chile was to study how increased input of ammonium (NH4) and phosphate (PO4) from salmon farms might affect the community structure of bacteria in surface waters where fish farms are located. We used microcosms (35 l) with NH4-N and PO4-P added to the natural seawater in a gradient of nutrient-loading rates, with the same N:P ratio as in salmon aquaculture effluents. Additionally, we measured bacterial community structure at different depths in the Comau Fjord to assess the natural variation to compare with our experiment. We used denaturing gradient gel electrophoresis (DGGE) to create 16S rDNA fingerprints of the bacterial communities and monitored biological and environmental variables (chlorophyll a, inorganic nutrients, pH, microbial abundance). The nutrient-loading rate had a significant impact on the bacterial community structure, and the community dissimilarity between low and high nutrient additions was up to 78%. Of the measured environmental variables, phytoplankton abundance and increased pH from photosynthesis had a significant effect. We observed no significant changes in bacterial diversity, which remained at the same level as in the unmanipulated community. Thus, the bacterial community of the fjord was not resistant, but resilient within the time frame and nutrient gradient of our experiment

Effect of hydroxamate and catecholate siderophores on iron availability in the diatom Skeletonema costatum: Implications of siderophore degradation by associated bacteria

The bioavailability of iron (Fe) across marine ecosystems, mainly determined by Fe speciation and species-specific requirements of phytoplankton, remains largely unresolved. Siderophores are relevant within the pool of organic ligands that control organic Fe speciation. The effect on growth and physiology of the diatom Skeletonema costatum following addition over time of the uncomplexed siderophores (apo-form) desferrioxamine B and enterobactin were studied in the laboratory. The diatom was grown in batch culture in concentration gradients up to 50 and 10,000 nM for enterobactin and desferrioxamine B respectively. The potential effect of siderophore degradation was analyzed by electrospray ionization mass spectroscopy (HPLC-ESI-MS). Growth of S. costatum was negatively correlated to desferrioxamine concentration. In treatments where >500 nM was added, growth was negligible until day 9 after which significant growth started. Fe uptake at day 9 was highest at 10,000 nM, while the Fe quota was the lowest. The addition of enterobactin had a negative effect on the abundance, the in-vivo fluorescence and the Fe quota in S. costatum only at the highest concentration of 50 nM, while the in-vivo fluorescence was enhanced at the lowest concentration. The bacterial abundance over time was also negatively correlated to the concentration for both siderophores, but at day 9 the bacterial uptake showed an increase proportional to the siderophore concentration. HPLC-ESI-MS analysis revealed the presence of tentative metabolites of desferrioxamine in 500 and 10,000 nM indicating changes in concentration of the apo-siderophore. In the presence of cathecolate and hydroxamate siderophores, S. costatum exhibited the capacity for different Fe uptake strategies. The late growth exhibited and the high Fe uptake after prolonged Fe-limited growth, suggests that Fe reduction at cell's membrane may be facilitated by possible degradation of desferrioxamine by the associated bacteria. The results emphasize the need for studying Fe bioavailability of algae together with the interacting bacterial community

Climate change mitigation effects: How do potential CO2 leaks from a sub-seabed storage site in the Norwegian Sea affect Astarte sp. bivalves?

Carbon capture and storage (CCS) is one of the most promising mitigation strategies for reducing the emissions of carbon dioxide (CO2) to the atmosphere and may substantially help to decelerate global warming. There is an increasing demand for CCS sites. Nevertheless, there is a lack of knowledge of the environmental risk associated with potential leakage of CO2 from the storage sites; and even more, what happens when the seepage stops. Can the environment return to the initial equilibrium? Potential effects on native macrofauna were studied under a scenario of a 50-day CO2 leakage, and the subsequent leak closure. To accomplish the objective, Trondheim Fjord sediments and clams were exposed to an acidified environment (pH 6.9) at 29 atm for 7 weeks followed by a 14-day recovery at normal seawater conditions (pH 8.0, 29 atm). Growth and survival of clams exposed to pressure (29 atm) and reduced pH (6.9) did not significantly differ from control clams kept at 1 atm in natural seawater. Furthermore, bioaccumulation of elements in the soft tissue of clams did not register significant variations for most of the analysed elements (Cd, Cr, Pb, and Ti), while other elements (As, Cu, Fe, Ni) had decreasing concentrations in tissues under acidified conditions in contrast to Na and Mg, which registered an uptake (Ku) of 111 and 9.92 μg g−1dw d−1, respectively. This Ku may be altered due to the stress induced by acidification; and the element concentration being released from sediments was not highly affected at that pH. Therefore, a 1 unit drop in pH at the seafloor for several weeks does not appear to pose a risk for the clams

Stakeholder Perceptions of Links between Environmental Changes to their Socio-Ecological System and their Adaptive Capacity in the Region of Troms, Norway

Climate change affects the marine environment at all levels of governance. At a global level, researchers expect the projected increase in sea surface temperature to facilitate large changes in the marine food web, which in turn will affect both global fisheries and aquaculture. At the local level, government and stakeholders want to know whether and how this affects their local communities and their adaptive capacity in light of this. Research suggests that risk communication of the effects of changes in the marine food web suffers from stakeholders' short-term mentality and narrow boundaries. This in turn can lead to an underestimation of the potential risks associated with climate change. We explore this theory by mapping the perceptions of marine stakeholders in the region of Troms, Norway. We first developed cognitive maps in a workshop setting, and then used system conceptualization to analyze the feedback mechanisms of the system qualitatively using fuzzy cognitive mapping. We examined the outcomes and compared them for different scenarios using a simple MatLab script. Results demonstrated that stakeholders did not underestimate their risks to climate change. They were aware of environmental changes, and they perceived that a changing climate was the cause of this change, and that it was indeed affecting their livelihoods—and would continue to do so in the future

Weddell-Scotia Confluence Effect on the Iron Distribution in Waters Surrounding the South Shetland (Antarctic Peninsula) and South Orkney (Scotia Sea) Islands During the Austral Summer in 2007 and 2008

An oceanographic survey around the South Shetland Islands (SSI) and the South Orkney Islands (SOI) was conducted during January 2007 and February 2008, respectively, as part of the United States Antarctic Marine Living Resources (AMLR) program ecosystems surveys. At 27 stations, concentrations of dissolved labile Fe (DFe) and total acid leachable (unfiltered, TaLFe) iron (Fe) were measured in the upper 200 m (including coastal and oceanic waters) to better resolve the factors limiting primary production in these regions. Northwest of the SSI, a region influenced by Drake Passage (DP) waters, mean DFe (∼0.26 nM) and TaLFe (∼1.02 nM) concentrations were the lowest, whereas intermediate concentrations for both DFe and TaLFe were measured in the Bransfield Strait (BS). Around Elephant Island (EI), over and off the continental shelf, Fe concentrations differed between the west and the east margins. DFe and TaLFe concentrations further support the argument that the effect of the Shackleton Transverse Ridge (STR) is a crucial structure affecting both the Fe and the chlorophyll distributions in this region. The waters around the SOI had DFe concentrations higher than those in the SSI, with the area north of the South Scotia Ridge (SSR) (60°S), having the highest DFe (0.54 nM) concentrations and the waters in Powell Basin (PB) having the lowest DFe (1.17 nM) and TaLFe (4.51 nM) and concentrations. These spatial patterns of Fe suggest that there are different Fe inputs from shelf waters near the Antarctic Slope Front (ASF). The overall TaLFe:DFe ratios, used as indicator for understanding the relative distance of Fe sources, were lower around the SOI compared to those in the SSI, suggesting that the Fe source for SOI waters was more distant. The spatial patterns between Fe and chlorophyll-a (Chl-a) concentrations in relation to the hydrography highlight the complexity and variability of the oceanographic processes in the region. These results improve the knowledge on the Fe sources and inputs in the less known SOI waters during the austral summer, and they further support the importance of advective processes from the Fe-rich waters that flow from the eastern margin of the Antarctic Peninsula (AP) into the Weddell-Scotia Confluence (WSC)

Iron Speciation and Physiological Analysis Indicate that Synechococcus sp. PCC 7002 Reduces Amorphous and Crystalline Iron Forms in Synthetic Seawater Medium

Cyanobacteria have high iron requirements due to iron-rich photosynthetic machineries. Despite the high concentrations of iron in the Earth’s crust, iron is limiting in many marine environments due to iron’s low solubility. Oxic conditions leave a large portion of the ocean’s iron pool unavailable for biotic uptake, and so the physiochemical properties of iron are hugely important for iron’s bioavailability. Our study is the first to investigate the effect of iron source on iron internalization and extracellular reduction by Synechococcus sp. PCC 7002. The results indicated that the amorphous iron hydrolysis species produced by FeCl3 better support growth in Synechococcus through more efficient iron internalization and a larger degree of extracellular reduction of iron than the crystalline FeO(OH). An analysis of dissolved iron (II) indicated that biogenic reduction took place in cultures of Synechococcus grown on both FeCl3 and FeO(OH)