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  • Articles  (7)
  • Open Access-Papers  (7)
  • 1
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    Shell formation and microstucture of the ocean quahog Arctica islandica: Does ocean acidification matter? (2013)
    Staats- und Universitaetsbibliothek Bremen
    In:  EPIC3Staats- und Universitaetsbibliothek Bremen, 143 p.
    Details
    Publication Date: 2019-07-17
    Description: Carbon dioxide concentration (pCO2) in the ocean is steadily increasing causing a drop of pH, consequently turning the surface seawater more acidic. Due to possible adaptation mechanisms some marine organisms can cope better with high pCO2 and low pH than others. The ocean quahog Arctica islandica is widely distributed in the North Atlantic region. Populations of this species are also well established in the high fluctuating environment of the Kiel Bight in the Western Baltic Sea and show high tolerance to environmental parameters like salinity, temperature and low oxygen levels. In my thesis I am interested in the performance of A. islandica from Kiel Bight to build and maintain its shell in a high pCO2 environment and the general aspects of bivalve shell properties as well as the site of calcification within the bivalve as a prerequisite for a mechanistic understanding of the biomineralization process. This thesis summarizes i) A. islandica from Kiel Bight populations is resistant and most likely pre-adapted towards elevated pCO2 over a short period of time (90 days) and contributes to the fundamental understanding of ii) single organic shell-compounds identified as pigment polyenes, that are not habitat related and may contribute to shell formation and iii) the calcification process itself is not happening inside the bulk EPF but rather within a supersaturated microsite created by active ion pumping by the OME. Understanding the biomineralization process and all components involved is crucial and thus the next challenge in order to estimate the robustness of A. islandica and other marine calcifiers in a high pCO2 world.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Thesis , notRev
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  • 2
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    Physiological response of pectinid bivalves to an acidifying and warming ocean (2010)
    In:  EPIC3BIOACID / EPOCA / UKOARP Meeting, Bremerhaven, 2010-09-27-2010-09-30
    Details
    Publication Date: 2019-08-19
    Description: The aim of this research project is to analyse the physiological response of an active calcifier (bivalves) to ocean acidification (OA) and ocean warming on the organismic and cellular level. The work is based on a comparison between temperate (Pecten maximus) and sub-arctic (Chlamys islandica) pectinids. We investigate the effect of different OA scenarios (390, 750, 1120 ppm CO2) at two different temperature regimes (long-term acclimation to mean habitat and elevated temperature). The incubation of C. islandica and P. maximus at 0°C and 10°C, respectively, started using a re-circulated system. Preliminary results obtained on C. islandica after long-term incubation at 390 and 1120 ppm CO2 (≥8 weeks) suggest that OA has no impact on routine metabolism of the animals. Following exhausted exercise metabolic rate rose by a factor of ~2 in both groups indicating again similar rates in control and OA-exposed animals. Further analysis of aerobic and anaerobic metabolites during recovery phase will be conducted using NMR spectroscopy. Tissue samples from different organs will be taken for a mostly complete metabolic analysis (e.g. muscle, mantle, gill) and hemolymph pH will be measured. Energy dependent cellular processes such as ion regulation, protein synthesis will be determined by on-line profiling using Bionas® analyzing system.
    Repository Name: EPIC Alfred Wegener Institut
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  • 3
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    Elevated CO2 Levels do not Affect the Shell Structure of the Bivalve Arctica islandica from the Western Baltic (2013)
    In:  EPIC3PLoS ONE, 8(7), pp. e70106, ISSN: 1932-6203
    Details
    Publication Date: 2019-07-16
    Description: Shells of the bivalve Arctica islandica are used to reconstruct paleo-environmental conditions (e.g. temperature) via biogeochemical proxies, i.e. biogenic components that are related closely to environmental parameters at the time of shell formation. Several studies have shown that proxies like element and isotope-ratios can be affected by shell growth and microstructure. Thus it is essential to evaluate the impact of changing environmental parameters such as high pCO2 and consequent changes in carbonate chemistry on shell properties to validate these biogeochemical proxies for a wider range of environmental conditions. Growth experiments with Arctica islandica from the Western Baltic Sea kept under different pCO2 levels (from 380 to 1120 matm) indicate no affect of elevated pCO2 on shell growth or crystal microstructure, indicating that A. islandica shows an adaptation to a wider range of pCO2 levels than reported for other species. Accordingly, proxy information derived from A. islandica shells of this region contains no pCO2 related bias.
    Repository Name: EPIC Alfred Wegener Institut
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  • 4
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    THE DISTRIBUTION OF POLYENES IN THE SHELL OF ARCTICA ISLANDICA FROM NORTH ATLANTIC LOCALITIES: A CONFOCAL RAMAN MICROSCOPY STUDY (2014)
    Oxford Univ. Pr.
    In:  EPIC3Journal of Molluscan Studies, Oxford Univ. Pr., pp. 1-6, ISSN: 0260-1230
    Details
    Publication Date: 2014-06-13
    Description: Many of the pigments that are widely found in coloured parts of mollusc shells are polyenes, i.e. molecules with a central polyenic chain (carbon-carbon single and double bonds). Due to a resonant coupling of these molecules at wavelengths typically used in Raman spectroscopy, this method is well suited to investigate their occurrence in biogenic materials. Here we use confocal Raman microscopy to map the spatial distribution of polyenes within the shell of the bivalve Arctica islandica and to determine their chemical characteristics (chain length). Polyene chain length does not differ between shells from different localities (off Iceland, Baltic Sea and North Sea). We also show that the pigment polyenes are not only located at the outside of the shell, but also within the shell, developing the same layered pattern typical for growth bands. This finding raises the question as to whether polyenes may play a role in the biomineralization process itself.
    Repository Name: EPIC Alfred Wegener Institut
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  • 5
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    Great scallops – great loser of ocean acidification and -warming? (2011)
    In:  EPIC3BioAcid conference 2011, 2011-09-26-2011-09-28
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    Publication Date: 2019-08-19
    Description: The synergistic effects of ocean acidification (OA) and warming were studied on the king scallop (= great scallop; Pecten maximus, L.), an actively swimming calcifier. Metabolic activity and survival success were investigated on the organismic level using oxygen measurements and force recordings during routine metabolism and swimming activity (escape response), respectively. Experiments on P. maximus sampled during winter from Stavanger (Norway) incubated at 4°C and at 10°C for 6-8 weeks at CO2 levels of around 0.039 and 0.112 kPa (390 and 1120 ppm) in re-circulated systems suggest that OA alone has only an marginal impact on routine metabolism and escape response of the scallops. However, we found a significant reduction in both force production and on the quotient of exhausted exercise metabolism to routine metabolism (factorial aerobic scope) in the group incubated under elevated temperature and high CO2 conditions. Hemolymph data revealed, that exhausted animals had significant less oxygen and more CO2 in their hemolymph compared to animals under routine conditions. Scallops incubated at 0.039 kPa had less CO2 in their hemolymph compared to animals at high CO2 conditions. Our data support the hypothesis of Pörtner and Farrell (Science, 2008) that increased CO2 concentrations will effect thermal tolerance of scallops by narrowing the “window” of optimal life conditions.
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
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    Impact of ocean acidification on escape performance of the king scallop, Pecten maximus, from Norway (2013)
    SPRINGER
    In:  EPIC3Marine Biology, SPRINGER, 160(8), pp. 1995-2006, ISSN: 0025-3162
    Details
    Publication Date: 2017-01-16
    Description: The ongoing process of ocean acidification already affects marine life, and according to the concept of oxygen and capacity limitation of thermal tolerance, these effects may be intensified at the borders of the thermal tolerance window. We studied the effects of elevated CO2 concentrations on clapping performance and energy metabolism of the commercially important scallop Pecten maximus. Individuals were exposed for at least 30 days to 4 °C (winter) or to 10 °C (spring/summer) at either ambient (0.04 kPa, normocapnia) or predicted future PCO2 levels (0.11 kPa, hypercapnia). Cold-exposed (4 °C) groups revealed thermal stress exacerbated by PCO2 indicated by a high mortality overall and its increase from 55 % under normocapnia to 90 % under hypercapnia. We therefore excluded the 4 °C groups from further experimentation. Scallops at 10 °C showed impaired clapping performance following hypercapnic exposure. Force production was significantly reduced although the number of claps was unchanged between normocapnia- and hypercapnia-exposed scallops. The difference between maximal and resting metabolic rate (aerobic scope) of the hypercapnic scallops was significantly reduced compared with normocapnic animals, indicating a reduction in net aerobic scope. Our data confirm that ocean acidification narrows the thermal tolerance range of scallops resulting in elevated vulnerability to temperature extremes and impairs the animal’s performance capacity with potentially detrimental consequences for its fitness and survival in the ocean of tomorrow.
    Repository Name: EPIC Alfred Wegener Institut
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  • 7
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    In situ Measurements of pH, CA2+, and Dic Dynamics within the Extrapallial Fluid of the Ocean Quahog Arctica islandica (2019)
    National Shellfisheries Association
    In:  EPIC3Journal of Shellfish Research, National Shellfisheries Association, 38(1), pp. 71-78, ISSN: 0730-8000
    Details
    Publication Date: 2019-11-19
    Description: This study investigated to what extent the extrapallial fluid (EPF) of the marine bivalve Arctica islandica (Linneaus, 1767) is involved in shell formation. With in situ pH microscopy, pH gradients were identified between inner shell surface and outer mantle epithelium (OME). pH at the OME varied rapidly between neutral and values above 9, suggesting active H+ pumping. Microsensor measurements showed also remarkable short-term dynamics in pH and Ca2+ concentrations, again suggesting active ion pumping. Further focus was on pH, Ca2+, and dissolved inorganic carbon dynamics within the EPF to determine whether calcium carbonate precipitation is possible within the EPF. The data show that the bulk of the inner EPF rarely reaches calcium carbonate saturation and, thus, cannot be the site of shell formation. At the OME surface, however, pH levels of up to 9.5 were observed, corresponding to a 30-fold carbonate supersaturation. Thus, ion pumping by the OME can drive calcification when the OME is just a few mm distant from the inner shell surface, as it is the case in the outer EP
    Repository Name: EPIC Alfred Wegener Institut
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