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2. In-situ Bypass and Extra-anatomic Bypass Procedures Result in Similar Survival in Patients with Secondary Aorto-Enteric Fistulae

Author

Janko, M. R., Woo, K., Hacker, R. I., Baril, D., Bath, J., Smeds, M. R., Kashyap, V. S., Szeberin, Z., Magee, G. A., Elsayed, R., Wishy, A., John, St., Beck, R., Farber, A., Motta, M., Zhou, F., Lemmon, W. k., Coleman, G. l., Behrendt, D., C. -A., Aziz, Black, F., Shutze, J., Garrett, W., H. E. Jr., De Caridi, G., Liapis, C. D., Geroulakos, G., Kakisis, Moulakakis, J., Kakkos, K., Obara, S. K., Wang, H. v., Rhéaume, G., Davila, P., Ravin, V. y., Demartino, R. z., Milner, R., Shalhub, R., Jim, S., Lee, J., Dubuis, J., Ricco, C., J. -B., Coselli, Lemaire, J. a., Fatima, S., Sanford, J., Yoshida, J., Schermerhorn, W., Menard, M. L., Belkin, M., Blackwood, M., Conrad, S., Wang, Ml, Crofts, L., Nixon, S., Wu, T., Chiesa, T., Bose, R., Turner, S., Moore, J., Smith, R., Ciocca, J., Hsu, R, Czerny, J., Cullen, M., Kahlberg, J., Setacci, A., C. J., Senneville, J. H., Garrido, E., Sarac, P., Rizzo, T. P., Go, A., Bjorck, M. R., Gavali, M., Wanhainen, H., Lawrence, A., Chung, P. F., Janko, Matthew R, Woo, Karen, Hacker, Robert I, Baril, Donald, Bath, Jonathan, Smeds, Matthew R, Kashyap, Vikram S, Szeberin, Zoltan, Magee, Gregory, Elsayed, Ramsey, Wishy, Andrew, St John, Rebecca, Beck, Adam, Farber, Mark, Motta, Fernando, Zhou, Wei, Lemmon, Gary, Coleman, Dawn, Behrendt, Christian-Alexander, Aziz, Faisal, Black, Jame, Shutze, William, Garrett, H Edward, de Caridi, Giovanni, Liapis, Christo, Kakkos, Stavro, Obara, Hideaki, Wang, Grace, Rhéaume, Pascal, Davila, Victor, Ravin, Reid, Demartino, Randall, Milner, Ro, Shalhub, Sherene, Jim, Jeffrey, Lee, Jason, Dubuis, Celine, Ricco, Jean-Baptiste, Coselli, Joseph, Lemaire, Scott, Fatima, Jahvairiah, Sanford, Jennifer, Yoshida, Winston, Schermerhorn, Marc, Menard, Matthew, Belkin, Michael, Blackwood, Stuart, Conrad, Mark, Wang, Linda, Crofts, Sara, Nixon, Thoma, Wu, Timothy, Chiesa, Roberto, Bose, Saideep, Turner, Jason, Moore, Ryan, Smith, Justin, Ciocca, Rocco, Hsu, Jeffrey, Czerny, Martin, Cullen, Jonathan, Kahlberg, Andrea, Setacci, Carlo, Joh, Jin Hyun, Senneville, Eric, Garrido, Pedro, Sarac, Timur, Rizzo, Anthony, Go, Michael, Bjorck, Martin, Gavali, Hamid, Wanhainen, Ander, Lawrence, Peter F, and Chung, Jayer

Subjects
Male, medicine.medical_specialty, medicine.medical_treatment, Aortoenteric fistula, Aorta Aortoenteric fistula, 030204 cardiovascular system & hematology, Anastomosis, Revascularization, 03 medical and health sciences, Blood Vessel Prosthesis Implantation, 0302 clinical medicine, Interquartile range, medicine, Intestinal Fistula, Humans, 030212 general & internal medicine, Survival analysis, Aged, Retrospective Studies, Vascular Fistula, business.industry, Proportional hazards model, Hazard ratio, Middle Aged, Confidence interval, United States, Surgery, Survival Rate, Female, Stents, Cardiology and Cardiovascular Medicine, business, Follow-Up Studies
Abstract

The optimal revascularization modality in secondary aortoenteric fistula (SAEF) remains unclear in the literature. The purpose of this investigation was to determine the revascularization approach associated with the lowest morbidity and mortality using real-world data in patients with SAEF.A retrospective, multi-institutional study of SAEF from 2002 to 2014 was performed using a standardized database. Baseline demographics, comorbidities, and operative and postoperative variables were recorded. The primary outcome was long-term mortality. Descriptive statistics, Kaplan-Meier survival analysis, and univariate and multivariate analyses were performed.During the study period, 182 patients at 34 institutions from 11 countries presented with SAEF (median age, 72 years; 79% male). The initial aortic procedures that resulted in SAEF were 138 surgical grafts (76%) and 42 endografts (23%), with 2 unknown; 102 of the SAEFs (56%) underwent complete excision of infected aortic graft material, followed by in situ (in-line) bypass (ISB), including antibiotic-soaked prosthetic graft (53), autogenous femoral vein (neoaortoiliac surgery; 17), cryopreserved allograft (28), and untreated prosthetic grafts (4). There were 80 patients (44%) who underwent extra-anatomic bypass (EAB) with infected graft excision. Overall median Kaplan-Meier estimated survival was 319 days (interquartile range, 20-2410 days). Stratified by EAB vs ISB, there was no significant difference in Kaplan-Meier estimated survival (P = .82). In comparing EAB vs ISB, EAB patients were older (74 vs 70 years; P = .01), had less operative hemorrhage (1200 mL vs 2000 mL; P = .04), were more likely to initiate dialysis within 30 days postoperatively (15% vs 5%; P = .02), and were less likely to experience aorta-related hemorrhage within 30 days postoperatively (3% aortic stump dehiscence vs 11% anastomotic rupture; P = .03). There were otherwise no significant differences in presentation, comorbidities, and intraoperative or postoperative variables. Multivariable Cox regression showed that the duration of antibiotic use (hazard ratio, 0.92; 95% confidence interval, 0.86-0.98; P = .01) and rifampin use at time of discharge (hazard ratio, 0.20; 95% confidence interval, 0.05-0.86; P = .03) independently decreased mortality.These data suggest that ISB does not offer a survival advantage compared with EAB and does not decrease the risk of postoperative aorta-related hemorrhage. After repair, 50% of SAEF patients survive 10 months. Each week of antibiotic use decreases mortality by 8%. Further study with risk modeling is imperative for this population.

Published
2020

3. Thermochronological evidence for late Proterozoic (Vendian) cooling in southwest Wedel Jarlsberg Land, Spitsbergen

Author

Manecki, M., Holm, D.K., Czerny, J., and Lux, D.

Subjects
Svalbard -- Natural history, Geology, Stratigraphic -- Proterozoic, Amphiboles -- Research, Earth sciences
Abstract

Two Proterozoic terranes with different metamorphic histories are distinguished from geological mapping in southwestern Wedel Jarlsberg Land: a northern greenschist facies terrane and a southern amphibolite facies terrane which has been overprinted by greenschist facies metamorphism. To better characterize the tectonothermal history of these terranes we have obtained new [.sup.40]Ar/[.sup.39]Ar mineral dates from this area. A muscovite separate from the northern terrane yielded a Caledonian plateau age of 432 [+ or -] 7 Ma. The southern terrane yielded significantly older [.sup.40]Ar/[.sup.39]Ar ages with three muscovite plateau dates of 584 [+ or -] 14 Ma, 575 [+ or -] 15 Ma, and 459 [+ or -] 9 Ma, a 484 [+ or -] 5 Ma biotite plateau date, and a 616 [+ or -] 17 Ma hornblende plateau date. The oldest thermochronological dates are over 300 Ma younger than the age of amphibolite facies metamorphisin and therefore probably do not represent uplift-related cooling. Instead, the Vendian dates correlate well with a regionally widespread magmatic and metamorphic/thermal resetting event recognized within Caledonian complexes of northwestern Spitsbergen and Nordaustlandet. The apparent Ordovician dates are interpreted to represent partial resetting, suggesting that late Caledonian greenschist facies overprinting of the southern terrane was of variable intensity.

Published
1998

4. Influence of elevated CO2 concentrations on cell division and nitrogen fixation rates in the bloom-forming cyanobacterium Nodularia spumigena

Author

Czerny, J., Joana Ramos, and Riebesell, U.

Abstract

The surface ocean absorbs large quantities of the CO2 emitted to the atmosphere from human activities. As this CO2 dissolves in seawater, it reacts to form carbonic acid. While this phenomenon, called ocean acidification, has been found to adversely affect many calcifying organisms, some photosynthetic organisms appear to benefit from increasing [CO2]. Among these is the cyanobacterium Trichodesmium, a predominant diazotroph (nitrogen-fixing) in large parts of the oligotrophic oceans, which responded with increased carbon and nitrogen fixation at elevated pCO2. With the mechanism underlying this CO2 stimulation still unknown, the question arises whether this is a common response of diazotrophic cyanobacteria. In this study we therefore investigate the physiological response of Nodularia spumigena, a heterocystous bloom-forming diazotroph of the Baltic Sea, to CO2-induced changes in seawater carbonate chemistry. N. spumigena reacted to seawater acidification/carbonation with reduced cell division rates and nitrogen fixation rates, accompanied by significant changes in carbon and phosphorus quota and elemental composition of the formed biomass. Possible explanations for the contrasting physiological responses of Nodularia compared to Trichodesmium may be found in the different ecological strategies of non-heterocystous (Trichodesmium) and heterocystous (Nodularia) cyanobacteria.

Published
2018

5. A 13C labelling study on carbon fluxes in Arctic plankton communities under elevated CO2 levels

Author

de Kluijver, A., Soetaert, K., Czerny, J., Schulz, K.G., Boxhammer, T., Riebesell, U., and Middelburg, J.J.

Subjects
lcsh:Geology, lcsh:QH501-531, Aardwetenschappen, lcsh:QH540-549.5, fungi, lcsh:QE1-996.5, lcsh:Life, lcsh:Ecology
Abstract

The effect of CO2 on carbon fluxes in Arctic plankton communities was investigated during the 2010 EPOCA mesocosm study in Ny Ålesund, Svalbard. Nine mesocosms were set up with initial pCO2 levels ranging from 185 to 1420 μatm for 5 weeks. 13C labelled bicarbonate was added at the start of the experiment to follow the transfer of carbon from dissolved inorganic carbon (DIC) into phytoplankton, bacteria, total particulate organic carbon (POC), zooplankton, and settling particles. Polar lipid derived fatty acids (PLFA) were used to trace carbon dynamics of phytoplankton and bacteria and allowed distinction of two groups of phytoplankton: phyto I (autotrophs) and phyto II (mixotrophs). Nutrients were added on day 13. A nutrient-phytoplankton-zooplankton-detritus model amended with 13C dynamics was constructed and fitted to the data to quantify uptake rates and carbon fluxes in the plankton community during the phase prior to nutrient addition (phase 1, days 0–12). During the first 12 days, a phytoplankton bloom developed that was characterized by high growth rates (0.87 days−1) for phyto I and lower growth rates (0.18 days−1) for phyto II. A large part of the carbon fixed by phytoplankton (~31%) was transferred to bacteria, while mesozooplankton grazed only ~6% of the production. After 6 days, the bloom collapsed and part of the organic matter subsequently settled into the sediment traps. The sedimentation losses of detritus in phase 1 were low (0.008 days−1) and overall export was only ~7% of production. Zooplankton grazing and detritus sinking losses prior to nutrient addition were sensitive to CO2: grazing decreased with increasing CO2, while sinking increased. Phytoplankton production increased again after nutrient addition on day 13. Although phyto II showed initially higher growth rates with increasing CO2 (days 14–22), the overall production of POC after nutrient addition (phase 2, days 14–29) decreased with increasing CO2. Significant sedimentation occurred towards the end of the experiment (after day 24) and much more material settled down in the sediment traps at low CO2.

Published
2013

6. Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord

Author

Niehoff, B., Schmithüsen, T., Knüppel, N., Dasse, M., Czerny, J., and Boxhammer, T.

Subjects
lcsh:Geology, lcsh:QH501-531, lcsh:QH540-549.5, lcsh:QE1-996.5, lcsh:Life, lcsh:Ecology
Abstract

The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world oceans. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated pCO2 are yet lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Samples were taken weekly over a six-week period with an Apstein net (55 μm mesh size) in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analyzed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (cirripeds, polychaetes, bivalves, gastropod, and decapods) dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica) were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms; the pCO2 had no significant effect on the overall community structure. However, single taxa responded to elevated CO2 concentrations. The ratio of cirripedia nauplii to cypris larvae, the next developmental stage, in the sediment traps averaged over the entire experiment increased with pCO2 and this suggests that increased pCO2 may have delayed their development. Also, the number of bivalves, averaged over the experimental period, decreased significantly with increasing pCO2. The nature of the CO2 effect, either direct or indirect, remains open and needs to be addressed in future.

Published
2013

7. Effects of ocean acidification on pelagic carbon fluxes in a mesocosm experiment

Author

Spilling, K., Schulz, K.G., Paul, A.J., Boxhammer, T., Achterberg, E.P., Hornick, T., Lischka, S., Stuhr, A., Bermúdez, R., Czerny, J., Crawfurd, K., Brussaard, C.P.D., Grossart, H.-P., Riebesell, U., Spilling, K., Schulz, K.G., Paul, A.J., Boxhammer, T., Achterberg, E.P., Hornick, T., Lischka, S., Stuhr, A., Bermúdez, R., Czerny, J., Crawfurd, K., Brussaard, C.P.D., Grossart, H.-P., and Riebesell, U.

Abstract

About a quarter of anthropogenic CO2 emissions are currently taken up by the oceans, decreasing seawater pH. We performed a mesocosm experiment in the Baltic Sea in order to investigate the consequences of increasing CO2 levels on pelagic carbon fluxes. A gradient of different CO2 scenarios, ranging from ambient ( ∼ 370 µatm) to high ( ∼ 1200 µatm), were set up in mesocosm bags ( ∼ 55 m3). We determined standing stocks and temporal changes of total particulate carbon (TPC), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and particulate organic carbon (POC) of specific plankton groups. We also measured carbon flux via CO2 exchange with the atmosphere and sedimentation (export), and biological rate measurements of primary production, bacterial production, and total respiration. The experiment lasted for 44 days and was divided into three different phases (I: t0–t16; II: t17–t30; III: t31–t43). Pools of TPC, DOC, and DIC were approximately 420, 7200, and 25 200 mmol C m−2 at the start of the experiment, and the initial CO2 additions increased the DIC pool by ∼ 7 % in the highest CO2 treatment. Overall, there was a decrease in TPC and increase of DOC over the course of the experiment. The decrease in TPC was lower, and increase in DOC higher, in treatments with added CO2. During phase I the estimated gross primary production (GPP) was ∼ 100 mmol C m−2 day−1, from which 75–95 % was respired, ∼ 1 % ended up in the TPC (including export), and 5–25 % was added to the DOC pool. During phase II, the respiration loss increased to ∼ 100 % of GPP at the ambient CO2 concentration, whereas respiration was lower (85–95 % of GPP) in the highest CO2 treatment. Bacterial production was ∼ 30 % lower, on average, at the highest CO2 concentration than in the controls during phases II and III. This resulted in a higher accumulation of DOC and lower reduction in the TPC pool in the elevated CO2 treatments at the end of phase II extending throughout phase III

Published
2016

8. Effect of increased pCO2 on the planktonic metabolic balance during a mesocosm experiment in an Arctic fjord

Author

Tanaka, T., Alliouane, S., Bellerby, R. G. B., Czerny, J., Kluijver, A., Riebesell, U., Schulz, K. G., Silyakova, A., Gattuso, J. -P., Observatoire océanologique de Villefranche-sur-mer (OOVM), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), CNRS-INSU, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
lcsh:Geology, lcsh:QH501-531, lcsh:QH540-549.5, lcsh:QE1-996.5, lcsh:Life, lcsh:Ecology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract

The effect of ocean acidification on the balance between gross community production (GCP) and community respiration (CR) (i.e., net community production, NCP) of plankton communities was investigated in summer 2010 in Kongsfjorden, west of Svalbard. Surface water, which was characterized by low concentrations of dissolved inorganic nutrients and chlorophyll a (a proxy of phytoplankton biomass), was enclosed in nine mesocosms and subjected to eight pCO2 levels (two replicated controls and seven enhanced pCO2 treatments) for one month. Nutrients were added to all mesocosms on day 13 of the experiment, and thereafter increase of chlorophyll a was provoked in all mesocosms. No clear trend in response to increasing pCO2 was found in the daily values of NCP, CR, and GCP. For further analysis, these parameters were cumulated for the following three periods: phase 1 – end of CO2 manipulation until nutrient addition (t4 to t13); phase 2 – nutrient addition until the second chlorophyll a minimum (t14 to t21); phase 3 – the second chlorophyll a minimum until the end of this study (t22 to t28). A significant response was detected as a decrease of NCP with increasing pCO2 during phase 3. CR was relatively stable throughout the experiment in all mesocosms. As a result, the cumulative GCP significantly decreased with increasing pCO2 during phase 3. After the nutrient addition, the ratios of cumulative NCP to cumulative consumption of NO3 and PO4 showed a significant decrease during phase 3 with increasing pCO2. The results suggest that elevated pCO2 influenced cumulative NCP and stoichiometric C and nutrient coupling of the plankton community in a high-latitude fjord only for a limited period. However provided that there were some differences or weak correlations between NCP data based on different methods in the same experiment, this conclusion should be taken with caution.

Published
2013
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17. Pelagic community production and carbon-nutrient stoichiometry under variable ocean acidification in an Arctic fjord

Author

Silyakova, A., Bellerby, R. G. J., Schulz, K. G., Czerny, J., Tanaka, T., Nondal, G., Riebesell, U., Engel, A., De Lange, T., Ludvig, A., Silyakova, A., Bellerby, R. G. J., Schulz, K. G., Czerny, J., Tanaka, T., Nondal, G., Riebesell, U., Engel, A., De Lange, T., and Ludvig, A.

Abstract

Net community production (NCP) and carbon to nutrient uptake ratios were studied during a large-scale mesocosm experiment on ocean acidification in Kongsfjorden, western Svalbard, during June-July 2010. Nutrient depleted fjord water with natural plankton assemblages, enclosed in nine mesocosms of similar to 50m(3) in volume, was exposed to pCO(2) levels ranging initially from 185 to 1420 mu atm. NCP estimations are the cumulative change in dissolved inorganic carbon concentrations after accounting for gas exchange and total alkalinity variations. Stoichiometric coupling between inorganic carbon and nutrient net uptake is shown as a ratio of NCP to a cumulative change in inorganic nutrients. Phytoplankton growth was stimulated by nutrient addition half way through the experiment and three distinct peaks in chlorophyll a concentration were observed during the experiment. Accordingly, the experiment was divided in three phases. Cumulative NCP was similar in all mesocosms over the duration of the experiment. However, in phases I and II, NCP was higher and in phase III lower at elevated pCO(2). Due to relatively low inorganic nutrient concentration in phase I, C : N and C : P uptake ratios were calculated only for the period after nutrient addition (phase II and phase III). For the total post-nutrient period (phase II+ phase III) ratios were close to Redfield, however they were lower in phase II and higher in phase III. Variability of NCP, C : N and C : P uptake ratios in different phases reflects the effect of increasing CO2 on phytoplankton community composition and succession. The phytoplankton community was composed predominantly of haptophytes in phase I, prasinophytes, dinoflagellates, and cryptophytes in phase II, and haptophytes, prasinophytes, dinoflagellates and chlorophytes in phase III (Schulz et al., 2013). Increasing ambient inorganic carbon concentrations have also been shown to promote primary production and carbon assimilation. For this study, it is clea

Published
2013
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18. Temporal biomass dynamics of an Arctic plankton bloom in response toincreasing levels of atmospheric carbon dioxide

Author

Schulz, K.G., Bellerby, R.G.J., Brussaard, C.P.D., Büdenbender, J., Czerny, J., Engel, A., Fischer, M., Koch-Klavsen, S., Krug, S.A., Lischka, S., Ludwig, A., Meyerhöfer, M., Nondal, G., Silyakova, A., Stuhr, A., Riebesell, U., Schulz, K.G., Bellerby, R.G.J., Brussaard, C.P.D., Büdenbender, J., Czerny, J., Engel, A., Fischer, M., Koch-Klavsen, S., Krug, S.A., Lischka, S., Ludwig, A., Meyerhöfer, M., Nondal, G., Silyakova, A., Stuhr, A., and Riebesell, U.

Abstract

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 Kongsfjorden on the west coast of Spitsbergen (Norway), 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 mu atm. 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 as 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 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.

Published
2013

19. Response of halocarbons to ocean acidification in the Arctic

Author

Hopkins, F.E., Kimmance, S.A., Stephens, J.A., Bellerby, R.G.J., Brussaard, C.P.D., Czerny, J., Schulz, K.G., Archer, S.D., Hopkins, F.E., Kimmance, S.A., Stephens, J.A., Bellerby, R.G.J., Brussaard, C.P.D., Czerny, J., Schulz, K.G., and Archer, S.D.

Abstract

The potential effect of ocean acidification (OA) on seawater halocarbons in the Arctic was investigated during a mesocosm experiment in Spitsbergen in June-July 2010. Over a period of 5 weeks, natural phytoplankton communities in nine similar to 50 m(3) mesocosms were studied under a range of pCO(2) treatments from similar to 185 mu atm to similar to 1420 mu atm. In general, the response of halocarbons to pCO(2) was subtle, or undetectable. A large number of significant correlations with a range of biological parameters (chlorophyll a, microbial plankton community, phytoplankton pigments) were identified, indicating a biological control on the concentrations of halocarbons within the mesocosms. The temporal dynamics of iodomethane (CH3I) alluded to active turnover of this halocarbon in the mesocosms and strong significant correlations with biological parameters suggested a biological source. However, despite a pCO(2) effect on various components of the plankton community, and a strong association between CH3I and biological parameters, no effect of pCO(2) was seen in CH3I. Diiodomethane (CH2I2) displayed a number of strong relationships with biological parameters. Furthermore, the concentrations, the rate of net production and the sea-to-air flux of CH2I2 showed a significant positive response to pCO(2). There was no clear effect of pCO(2) on bromocarbon concentrations or dynamics. However, periods of significant net loss of bromoform (CHBr3) were found to be concentration-dependent, and closely correlated with total bacteria, suggesting a degree of biological consumption of this halocarbon in Arctic waters. Although the effects of OA on halocarbon concentrations were marginal, this study provides invaluable information on the production and cycling of halocarbons in a region of the world's oceans likely to experience rapid environmental change in the coming decades.

Published
2013

20. Effect of increased pCO2 on the planktonic metabolic balance during a mesocosm experiment in an Arctic fjord

Author

Tanaka, T, Alliouane, S., Bellerby, R. G. B., Czerny, J., de Kluijver, A., Riebesell, Ulf, Schulz, Kai G., Silyakova, A., Gattuso, J.-P., Tanaka, T, Alliouane, S., Bellerby, R. G. B., Czerny, J., de Kluijver, A., Riebesell, Ulf, Schulz, Kai G., Silyakova, A., and Gattuso, J.-P.

Abstract

The effect of ocean acidification on the balance between gross community production (GCP) and community respiration (CR) (i.e., net community production, NCP) of plankton communities was investigated in summer 2010 in Kongsfjorden, west of Svalbard. Surface water, which was characterized by low concentrations of dissolved inorganic nutrients and chlorophyll a (a proxy of phytoplankton biomass), was enclosed in nine mesocosms and subjected to eight pCO2 levels (two replicated controls and seven enhanced pCO2 treatments) for one month. Nutrients were added to all mesocosms on day 13 of the experiment, and thereafter increase of chlorophyll a was provoked in all mesocosms. No clear trend in response to increasing pCO2 was found in the daily values of NCP, CR, and GCP. For further analysis, these parameters were cumulated for the following three periods: phase 1 – end of CO2 manipulation until nutrient addition (t4 to t13); phase 2 – nutrient addition until the second chlorophyll a minimum (t14 to t21); phase 3 – the second chlorophyll a minimum until the end of this study (t22 to t28). A significant response was detected as a decrease of NCP with increasing pCO2 during phase 3. CR was relatively stable throughout the experiment in all mesocosms. As a result, the cumulative GCP significantly decreased with increasing pCO2 during phase 3. After the nutrient addition, the ratios of cumulative NCP to cumulative consumption of NO3 and PO4 showed a significant decrease during phase 3 with increasing pCO2. The results suggest that elevated pCO2 influenced cumulative NCP and stoichiometric C and nutrient coupling of the plankton community in a high-latitude fjord only for a limited period. However provided that there were some differences or weak correlations between NCP data based on different methods in the same experiment, this conclusion should be taken with caution.

Published
2013
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21. Element budgets in an Arctic mesocosm CO2 perturbation study

Author

Engel, Anja, Czerny, J., Bellerby, R., Boxhammer, T., Ludwig, A., Nachtigall, K., Nondal, G., Silyakova, A., Sswat, M., Riebesell, U., Engel, Anja, Czerny, J., Bellerby, R., Boxhammer, T., Ludwig, A., Nachtigall, K., Nondal, G., Silyakova, A., Sswat, M., and Riebesell, U.

Published
2011

22. A strike-slip terrane boundary in Wedel Jarlsberg Land, Svalbard, and its bearing on correlations of SW Spitsbergen with the Pearya terrane and Timanide belt

Author

Mazur, S., Czerny, J., Majka, Jaroslaw, Manecki, M., Holm, D.K., Smyrak, A., Wypych, A., Mazur, S., Czerny, J., Majka, Jaroslaw, Manecki, M., Holm, D.K., Smyrak, A., and Wypych, A.

Abstract

Southwest Spitsbergen, Wedel Jarlsberg Land consists of two Proterozoic terranes with differing structural and metamorphic histories. The northern terrane experienced two Early Palaeozoic deformation events both accompanied by greenschist-facies metamorphism of similar grade. The southern terrane records a Neoproterozoic pervasive amphibolite-facies metamorphism and strong deformational fabric only locally retrogressed during a Caledonian greenschist-grade event. The terranes are seperated by an important sinistral ductile shear zone defined as the Vimsodden Kosibapasset zone, which comprises wrench- and contraction-dominated domains characteristic of strain partitioning in transpression zones; in this case apparently controlled by contrasting rheologies of the juxtaposed crustal domains. The northern terrane of Wedel Jarlsberg Land shares affinities with Pearya in northern Ellesmere Island of Arctic Canada whereas the southern one resembles the Timanide belt of NE Europe. A quantitative approach facilitated by a numerical plate model demonstrates that correlation with Pearya is feasible if sinistral displacement of c. 600 km occurred during the Caledonian orogeny. The correlation with the Timanides is valid if the southern terrane represents an outlier of the Timanide belt seperated from Baltica by the opening of the lapetus Ocean.

Published
2009
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24. Implications of elevated CO<sub>2</sub> on pelagic carbon fluxes in an Arctic mesocosm study – an elemental mass balance approach

Author

Czerny, J., primary, Schulz, K. G., additional, Boxhammer, T., additional, Bellerby, R. G. J., additional, Büdenbender, J., additional, Engel, A., additional, Krug, S. A., additional, Ludwig, A., additional, Nachtigall, K., additional, Nondal, G., additional, Niehoff, B., additional, Silyakova, A., additional, and Riebesell, U., additional

Published
2013
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30. Temporal biomass dynamics of an Arctic plankton bloom in response to increasing levels of atmospheric carbon dioxide

Author

Schulz, K. G., primary, Bellerby, R. G. J., additional, Brussaard, C. P. D., additional, Büdenbender, J., additional, Czerny, J., additional, Engel, A., additional, Fischer, M., additional, Koch-Klavsen, S., additional, Krug, S. A., additional, Lischka, S., additional, Ludwig, A., additional, Meyerhöfer, M., additional, Nondal, G., additional, Silyakova, A., additional, Stuhr, A., additional, and Riebesell, U., additional

Published
2013
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34. Temporal biomass dynamics of an Arctic plankton bloom in response to increasing levels of atmospheric carbon dioxide

Author

Schulz, K. G., primary, Bellerby, R. G. J., additional, Brussaard, C. P. D., additional, Büdenbender, J., additional, Czerny, J., additional, Engel, A., additional, Fischer, M., additional, Koch-Klavsen, S., additional, Krug, S. A., additional, Lischka, S., additional, Ludwig, A., additional, Meyerhöfer, M., additional, Nondal, G., additional, Silyakova, A., additional, Stuhr, A., additional, and Riebesell, U., additional

Published
2012
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36. Element budgets in an Arctic mesocosm CO2 perturbation study

Author

Czerny, J., primary, Schulz, K. G., additional, Boxhammer, T., additional, Bellerby, R. G. J., additional, Büdenbender, J., additional, Engel, A., additional, Krug, S. A., additional, Ludwig, A., additional, Nachtigall, K., additional, Nondal, G., additional, Niehoff, B., additional, Siljakova, A., additional, and Riebesell, U., additional

Published
2012
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46. Technical Note: Sampling and processing of mesocosm sediment trap material for quantitative biogeochemical analysis.

Author

Boxhammer, T., Bach, L. T., Czerny, J., and Riebesell, U.

Subjects
SEDIMENTS, QUANTITATIVE research, BIOGEOCHEMISTRY, PLANKTON physiology, EUPHOTIC zone, FREEZE-drying
Abstract

Sediment traps are the most common tool to investigate vertical particle flux in the marine realm. However, the spatial decoupling between particle formation and collection often handicaps reconciliation of these two processes even within the euphotic zone. Pelagic mesocosms have the advantage of being closed systems and are therefore ideally suited to study how processes in natural plankton communities influence particle formation and settling in the ocean's surface. We therefore developed a protocol for efficient sample recovery and processing of quantitatively collected pelagic mesocosm sediment trap samples. Sedimented material was recovered by pumping it under gentle vacuum through a silicon tube to the sea surface. The particulate matter of these samples was subsequently concentrated by passive settling, centrifugation or flocculation with ferric chloride and we discuss the advantages of each approach. After concentration, samples were freeze-dried and ground with an easy to adapt procedure using standard lab equipment. Grain size of the finely ground samples ranges from fine to coarse silt (2-63 µm), which guarantees homogeneity for representative subsampling, a widespread problem in sediment trap research. Subsamples of the ground material were perfectly suitable for a variety of biogeochemical measurements and even at very low particle fluxes we were able to get a detailed insight on various parameters characterizing the sinking particles. The methods and recommendations described here are a key improvement for sediment trap applications in mesocosms, as they facilitate processing of large amounts of samples and allow for high-quality biogeochemical flux data. [ABSTRACT FROM AUTHOR]

Published
2015
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47. Effects of CO2 perturbation on phosphorus pool sizes and uptake in a mesocosm experiment during a low productive summer season in the northern Baltic Sea.

Author

Nausch, M., Bach, L., Czerny, J., Goldstein, J., Grossart, H. P., Hellemann, D., Hornick, T., Achterberg, E., Schulz, K., and Riebesell, U.

Subjects
PHOSPHORUS cycle (Biogeochemistry), PHYTOPLANKTON, ADENOSINE triphosphate, SUMMER
Abstract

Studies investigating the effect of increasing CO2 levels on the phosphorus cycle in natural waters are lacking although phosphorus often controls phytoplankton development in aquatic systems. The aim of our study was to analyze effects of elevated CO2 levels on phosphorus pool sizes and uptake. Therefore, we conducted a CO2-manipulation mesocosm experiment in the Storfjärden (western Gulf of Finland, Baltic Sea) in summer 2012. We compared the phosphorus dynamics in different mesocosm treatments but also studied them outside the mesocosms in the surrounding fjord water. In the mesocosms as well as in surface waters of Storfjärden, dissolved organic phosphorus (DOP) concentrations of 0.26 ± 0.03 and 0.23 ± 0.04 μmol L−1, respectively, formed the main fraction of the total P-pool (TP), whereas phosphate (PO4) constituted the lowest fraction with mean concentration of 0.15 ± 0.02 μmol L−1 and 0.17 ± 0.07 μmol L−1 in the mesocosms and in the fjord, respectively. Uptake of PO4 ranged between 0.6 and 3.9 nmol L−1 h−1 of which ~ 86% (mesocosms) and ~ 72% (fjord) were realized by the size fraction < 3 μm. Adenosine triphosphate (ATP) uptake revealed that additional P was supplied from organic compounds accounting for 25–27% of P provided by PO4 only. CO2 additions did not cause significant changes in phosphorus (P) pool sizes, DOP composition, and uptake of PO4 and ATP when the whole study period was taken into account. About 18% of PO4 was transformed into POP, whereby the major proportion (~ 82%) was converted into DOP suggesting that the conversion of PO4 to DOP is the main pathway of the PO4 turnover. We observed that significant relationships (e.g., between POP and Chl a) in the untreated mesocosms vanished under increased fCO2 conditions. Consequently, it can be hypothesized that the relationship between POP formation and phytoplankton growth changed under elevated CO2 conditions. Significant short-term effects were observed for PO4 and particulate organic phosphorus (POP) pool sizes in CO2 treatments > 1000 µatm during periods when phytoplankton started to grow. [ABSTRACT FROM AUTHOR]

Published
2015
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48. No observed effect of ocean acidification on nitrogen biogeochemistry in a summer Baltic Sea plankton community.

Author

Paul, A. J., Achterberg, E. P., Bach, L. T., Boxhammer, T., Czerny, J., Haunost, M., Schulz, K.-G., Stuhr, A., and Riebesell, U.

Subjects
OCEAN acidification, BIOGEOCHEMISTRY, BIOTIC communities, ALGAL blooms
Abstract

Nitrogen fixation by filamentous cyanobacteria supplies significant amounts of new nitrogen (N) to the Baltic Sea. This balances N loss processes such as denitrification and anammox and forms an important N source supporting primary and secondary production in N-limited post-spring bloom plankton communities. Laboratory studies suggest that filamentous diazotrophic cyanobacteria growth and N2-fixation rates are sensitive to ocean acidification with potential implications for new N supply to the Baltic Sea. In this study, our aim was to assess the effect of ocean acidification on diazotroph growth and activity as well as the contribution of diazotrophically-fixed N to N supply in a natural plankton assemblage. We enclosed a natural plankton community in a summer season in the Baltic Sea near the entrance to the Gulf of Finland in six large-scale mesocosms (volume ~ 55 m3) and manipulated fCO2 over a range relevant for projected ocean acidification by the end of this century (average treatment fCO2: 365-1231 µatm). The direct response of diazotroph growth and activity was followed in the mesocosms over a 47 day study period during N-limited growth in the summer plankton community. Diazotrophic filamentous cyanobacteria abundance throughout the study period and N2-fixation rates (determined only until day 21 due to subsequent use of contaminated commercial 15N-N2 gas stocks) remained low. Thus estimated new N inputs from diazotrophy were too low to relieve N limitation and stimulate a summer phytoplankton bloom. Instead regeneration of organic N sources likely sustained growth in the plankton community. We could not detect significant CO2-related differences in inorganic or organic N pools sizes, or particulate matter N : P stoichiometry. Additionally, no significant effect of elevated CO2 on diazotroph activity was observed. Therefore, ocean acidification had no observable impact on N cycling or biogeochemistry in this N-limited, post-spring bloom plankton assemblage in the Baltic Sea. [ABSTRACT FROM AUTHOR]

Published
2015
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49. Effect of elevated CO2 on organic matter pools and fluxes in a summer, post spring-bloom Baltic Sea plankton community.

Author

Paul, A. J., Bach, L. T., Schulz, K.-G., Boxhammer, T., Czerny, J., Achterberg, E. P., Hellemann, D., Trense, Y., Nausch, M., Sswat, M., and Riebesell, U.

Subjects
PLANKTON populations, BIOGEOCHEMICAL cycles, CHEMICALS, MARINE organisms
Abstract

Ocean acidification is expected to influence plankton community structure and biogeo-chemical element cycles. To date, experiments with nutrient stimulated blooms have been primarily used to study the response of plankton communities to elevated CO2. In this CO2 manipulation study, we used large-volume (~ 55 m³) pelagic in situ meso-cosms to enclose a natural, post spring-bloom plankton assemblage in the Baltic Sea to investigate the response of organic matter pools to ocean acidification. In the meso-cosms, fCO2 was manipulated yielding a range of average fCO2 of 365 to ~ 1231 μatm with no adjustment of naturally available nutrient concentrations. Plankton community development and key biogeochemical element pools were subsequently followed in this nitrogen-limited ecosystem over a period of seven weeks. We identified three distinct phases based on temperature fluctuations and plankton biomass: a warm, productive period with elevated chlorophyll a and particulate matter concentrations (Phase I), a decline in autotrophic biomass coinciding with cooler water temperatures associated with lower incoming photosynthetically active radiation (PAR) and higher zooplankton grazing pressure (Phase II), and a steady state phase with low net change in particulate and dissolved matter pools (Phase III). We observed higher sustained chlorophyll a and particulate matter concentrations (~25% higher) and lower inorganic phosphate concentrations in the water column in the highest fCO2 treatment (1231 μatm) in Phase III. Size-fractionated phytoplankton pigment analyses indicated that these differences were driven by picophytoplankton (< 2μm) and were already established early in the experiment during Phase I. However the influence of picophytoplankton on bulk organic matter pools was masked by high biomass of larger plankton until Phase III when the small size fraction (< 2 μm) contributed up to 90% of chlorophyll a. Furthermore, CO2-related differences in water column suspended matter concentrations were not reflected in sinking material flux. Our results from this study indicate that ocean acidification could have significant and sustained impacts on pelagic biogeochemical element pools in nitrogen-limited ecosystems. [ABSTRACT FROM AUTHOR]

Published
2015
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