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959 Research products, page 1 of 96

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  • Open Access English
    Authors: 
    Shaviklo, A.; Mozafari, H.; Motamedzadegan, A.; Damavandi-Kamali, N.;

    Tuna processing by-product is estimated at more than 100,000 metric tonnes annually in Iran, which could be a potential source of edible protein in human food. Hence, recovering proteins from tuna by-products is a big achievement in the seafood industry. In this work tuna protein isolates (TPI) were extracted from dark/ red meat using the isoelectric solubilization/ precipitation method. Oxidative stability, biochemical indices and characteristics of the fatty acid composition of TPI (pH 6.5) containing 16.2% protein, 1.2% fat and mixed with a blend of salt and sucrose – as a cryostabilizer - and stored 6 months at -24°C were studied. The levels of peroxide (PV), TBARS, FFA and total volatile basic nitrogen (TVB-N) were significantly increased in TPI without cryostabilizers during the storage time. The results revealed that 22 fatty acids were identified in the light and dark tuna meat and TPI. The fatty acid composition of light and dark muscle of tuna and TPI containing salt and sucrose was the same. However a significant change was observed only in the TPI free from cryostabilizers during frozen storage. The results confirm inhibiting of lipid oxidation due to the incorporation of salt and sucrose to TPI. Published

  • Open Access English
    Authors: 
    Morris, K. J.; Herrera, S.; Gubili, C.; Tyler, P. A.; Rogers, A.; Hauton, C.;
    Project: EC | HERMIONE (226354)

    Despite being an abundant group of significant ecological importance the phylogenetic relationships of the Octocorallia remain poorly understood and very much understudied. We used 1132 bp of two mitochondrial protein-coding genes, nad2 and mtMutS (previously referred to as msh1), to construct a phylogeny for 161 octocoral specimens from the Atlantic, including both Isididae and non-Isididae species. We found that four clades were supported using a concatenated alignment. Two of these (A and B) were in general agreement with the of Holaxonia–Alcyoniina and Anthomastus–Corallium clades identified by previous work. The third and fourth clades represent a split of the Calcaxonia–Pennatulacea clade resulting in a clade containing the Pennatulacea and a small number of Isididae specimens and a second clade containing the remaining Calcaxonia. When individual genes were considered nad2 largely agreed with previous work with MtMutS also producing a fourth clade corresponding to a split of Isididae species from the Calcaxonia–Pennatulacea clade. It is expected these difference are a consequence of the inclusion of Isisdae species that have undergone a gene inversion in the mtMutS gene causing their separation in the MtMutS only tree. The fourth clade in the concatenated tree is also suspected to be a result of this gene inversion, as there were very few Isidiae species included in previous work tree and thus this separation would not be clearly resolved. A~larger phylogeny including both Isididae and non Isididae species is required to further resolve these clades.

  • Open Access English
    Authors: 
    de Kluijver Anna; Soetaert Karline; Schulz Kai Georg; Riebesell Ulf; Bellerby Richard G J; Middelburg Jack J;
    Project: EC | MEECE (212085), EC | EPOCA (211384)

    The potential impact of rising carbon dioxide (CO2) on carbon transfer from phytoplankton to bacteria was investigated during the 2005 PeECE III mesocosm study in Bergen, Norway. Sets of mesocosms, in which a phytoplankton bloom was induced by nutrient addition, were incubated under 1× (~350 μatm), 2× (~700 μatm), and 3× present day CO2 (~1050 μatm) initial seawater and sustained atmospheric CO2 levels for 3 weeks. 13C labelled bicarbonate was added to all mesocosms to follow the transfer of carbon from dissolved inorganic carbon (DIC) into phytoplankton and subsequently heterotrophic bacteria, and settling particles. Isotope ratios of polar-lipid-derived fatty acids (PLFA) were used to infer the biomass and production of phytoplankton and bacteria. Phytoplankton PLFA were enriched within one day after label addition, whilst it took another 3 days before bacteria showed substantial enrichment. Group-specific primary production measurements revealed that coccolithophores showed higher primary production than green algae and diatoms. Elevated CO2 had a significant positive effect on post-bloom biomass of green algae, diatoms, and bacteria. A simple model based on measured isotope ratios of phytoplankton and bacteria revealed that CO2 had no significant effect on the carbon transfer efficiency from phytoplankton to bacteria during the bloom. There was no indication of CO2 effects on enhanced settling based on isotope mixing models during the phytoplankton bloom, but this could not be determined in the post-bloom phase. Our results suggest that CO2 effects are most pronounced in the post-bloom phase, under nutrient limitation.

  • Open Access English
    Authors: 
    Alishahi, M.; Tollabi, M.; Ghorbanpour, M.;

    The success of many vaccines relies on their association with selected adjuvants in order to increase their immunogenicity and ensure long-term protection. Propolis is a natural compound, mostly known for its immunostimulatory properties. In this study the adjuvant effects of propolis in combination with formalin-killed Aeromonas hydrophila vaccine in Common carp (Cyprinus carpio) were evaluated and compared with Freund’s adjuvant. Three hundred juvenile carp (weighing 50.4±3.2 g) were divided randomly into four groups in triplicates. The fish were intraperitonealy injected with A. hydrophila bacterin (A.h) in combination with normal saline (Formalin Killed Bacterin, FKB group), Freund (FKB +F group), and Propolis (FKB +P group) respectively. The control group was injected with normal saline. Serum samples were taken from fish in each group every other week (days 0, 14, 28 and 42) of the experiment and immunological parameters including anti A. hydrophila antibody titer, serum lysozyme and antibacterial activity, complement activity, Nitro blue tetrazolium activity and serum total protein and globulin were compared among the groups. At the end of study the remaining fish in each group were challenged with virulent A. hydrophila and mortality was recorded for 10 days and Relative Percentage Survival (RPS) was calculated and compared among the groups. Results showed that although antibody titer and most of none specific immune responses increased in groups 2 and 3 compare to control group (p0.05). Besides no significant change was observed in mortality rate following the challenge in the propolis adjuvanted group compared with the FKB group (p>0.05). According to results, it can be concluded that although propolis as an adjuvant can promote some immune responses of common carp, it can't affect efficacy of vaccine and Ab titer of injected antigens, so it seems more work is needed to present propolis as a proper candidate for the development of a natural adjuvant in fish vaccines. Published

  • Open Access English
    Authors: 
    Mayer, Kathryn J;
    Publisher: eScholarship, University of California
    Country: United States

    Aerosol-cloud interactions are one of the largest sources of uncertainty in our understanding of the Earth’s climate system. In order to develop better predictive models and understand how the climate will respond to future changes in atmospheric composition, we must determine the sources and nature of aerosols which serve as cloud condensation nuclei (CCN), thus influencing the properties of clouds. Oceans cover 70% of the Earth’s surface and represent a major source of atmospheric aerosols. Sea spray aerosol (SSA) is formed by the action of breaking waves, whereas secondary marine aerosols (SMA) are formed from the oxidation products of gases emitted from the oceans. Biological activity in seawater (i.e. the life, death, and interactions of marine phytoplankton, bacteria, and viruses) can significantly affect the chemical composition of SSA through processing of dissolved organic matter and SMA through the emission of volatile gases. This dissertation investigates the cloud-relevant properties of SSA and SMA generated using ocean-atmosphere simulators in the laboratory, with a specific emphasis on the influence of biological activity in seawater on the properties of these aerosols. For the first time, SMA was produced from the oxidation of the headspace gases of a phytoplankton bloom grown in natural seawater, enabling measurements of its chemical composition and CCN activity. Overall, these studies show that the formation and properties of SMA are much more sensitive to biological activity in seawater than SSA. In addition, the chemical composition of SMA is highly dependent on the extent of photochemical oxidation, with a distinct shift from organic-rich to sulfate-rich composition in response to increased atmospheric aging. This change in SMA composition leads to a significant change in its hygroscopicity. These results suggest that the properties of SMA evolve temporally in the atmosphere, which has implications for CCN concentrations and cloud properties over the oceans.

  • Open Access English
    Authors: 
    Jokinen, Sami A; Virtasalo, Joonas J; Jilbert, Tom; Kaiser, Jérôme; Dellwig, Olaf; Arz, Helge Wolfgang; Hänninen, J; Arppe, Laura; Collander, Miia; Saarinen, Timo;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment. Here we present a 1500-year multiproxy record of near-bottom water redox changes from the coastal zone of the northern Baltic Sea, encompassing the climatic phases of the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), and the Modern Warm Period (MoWP). Our reconstruction shows that although multicentennial climate variability has modulated depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented, and besides gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. Alongside the anthropogenic nutrient input, the progressive deoxygenation since the beginning of the1900s was fueled by the combined effects of gradual shoaling of the basin and warming climate, which amplified sediment focusing and increased the vulnerability to hypoxia. Importantly, the eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s. We find no evidence of similar anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal water quality. Furthermore, this study highlights the need for combined use of sedimentological, ichnological, and geochemical proxies in order to robustly reconstruct subtle redox shifts especially in dynamic, non-euxinic coastal settings with strong seasonal contrasts in the bottom water quality.

  • Open Access English
    Authors: 
    Milzer, G.; Giraudeau, J.; Faust, J.; Knies, J.; Eynaud, F.; Rühlemann, C.;
    Project: EC | CASE (238111)

    Instrumental records from the Norwegian Sea and the Trondheimsfjord show evidence that changes of bottom water temperature and salinity in the fjord are linked to the salinity and temperature variability of the North Atlantic Current (NAC). Changes in primary productivity and salinity in the surface and intermediate water masses in the Trondheimsfjord as well as the fjord sedimentary budget are mainly driven by changes in riverine input. In this study we use 59 surface sediment samples that are evenly distributed in the fjord to examine whether dinocyst assemblages and stable isotope ratios of benthic foraminifera reflect the present-day hydrology and can be used as palaeoceanographic proxies. In general, modern benthic δ18O and δ13C values decrease from the fjord entrance towards the fjord head with lowest values close to river inlets. This is essentially explained by gradients in the amounts of fresh water and terrigenous organic matter delivered from the hinterland. The distribution of benthic δ13C ratios across the fjord is controlled by the origin (terrigenous vs. marine) of organic matter, local topography-induced variability in organic matter flux at the water–sediment interface, and organic matter degradation. The dinocyst assemblages display the variations in hydrography with respect to the prevailing currents, the topography, and the freshwater and nutrient supply from rivers. The strength and depth of the pycnocline in the fjord strongly vary seasonally and thereby affect water mass characteristics as well as nutrient availability, temporally creating local conditions that explain the observed species distribution. Our results prove that dinocyst assemblages and benthic foraminiferal isotopes reliably mirror the complex fjord hydrology and can be used as proxies of Holocene climatic variability.

  • Open Access English
    Authors: 
    Crise, Alessandro; Ribera d’Alcalà, Maurizio; Mariani, Patrizio; Petihakis, George; Robidart, Julie; Iudicone, Daniele; Bachmayer, Ralf; Malfatti, Francesca;
    Project: UKRI | Development and applicati... (NE/N006496/1), EC | JERICO-NEXT (654410), EC | AtlantOS (633211), EC | EMSO-Link (731036)

    In the field of ocean observing, the term of “observatory” is often used without a unique meaning. A clear and unified definition of observatory is needed in order to facilitate the communication in a multidisciplinary community, to capitalize on future technological innovations and to support the observatory design based on societal needs. In this paper, we present a general framework to define the next generation Marine OBservatory (MOB), its capabilities and functionalities in an operational context. The MOB consists of four interconnected components or “gears” (observation infrastructure, cyberinfrastructure, support capacity, and knowledge generation engine) that are constantly and adaptively interacting with each other. Therefore, a MOB is a complex infrastructure focused on a specific geographic area with the primary scope to generate knowledge via data synthesis and thereby addressing scientific, societal, or economic challenges. Long-term sustainability is a key MOB feature that should be guaranteed through an appropriate governance. MOBs should be open to innovations and good practices to reduce operational costs and to allow their development in quality and quantity. A deeper biological understanding of the marine ecosystem should be reached with the proliferation of MOBs, thus contributing to effective conservation of ecosystems and management of human activities in the oceans. We provide an actionable model for the upgrade and development of sustained marine observatories producing knowledge to support science-based economic and societal decisions. Refereed 14.A Manual (incl. handbook, guide, cookbook etc) 2018-09-07

  • Open Access English
    Authors: 
    Capet, A.; Beckers, J.-M.; Grégoire, M.;
    Project: EC | HYPOX (226213)

    The Black Sea northwestern shelf (NWS) is a shallow eutrophic area in which the seasonal stratification of the water column isolates the bottom waters from the atmosphere. This prevents ventilation from counterbalancing the large consumption of oxygen due to respiration in the bottom waters and in the sediments, and sets the stage for the development of seasonal hypoxia. A three-dimensional (3-D) coupled physical–biogeochemical model is used to investigate the dynamics of bottom hypoxia in the Black Sea NWS, first at seasonal and then at interannual scales (1981–2009), and to differentiate its driving factors (climatic versus eutrophication). Model skills are evaluated by a quantitative comparison of the model results to 14 123 in situ oxygen measurements available in the NOAA World Ocean and the Black Sea Commission databases, using different error metrics. This validation exercise shows that the model is able to represent the seasonal and interannual variability of the oxygen concentration and of the occurrence of hypoxia, as well as the spatial distribution of oxygen-depleted waters. During the period 1981–2009, each year exhibits seasonal bottom hypoxia at the end of summer. This phenomenon essentially covers the northern part of the NWS – which receives large inputs of nutrients from the Danube, Dniester and Dnieper rivers – and extends, during the years of severe hypoxia, towards the Romanian bay of Constanta. An index H which merges the aspects of the spatial and temporal extension of the hypoxic event is proposed to quantify, for each year, the intensity of hypoxia as an environmental stressor. In order to explain the interannual variability of H and to disentangle its drivers, we analyze the long time series of model results by means of a stepwise multiple linear regression. This statistical model gives a general relationship that links the intensity of hypoxia to eutrophication and climate-related variables. A total of 82% of the interannual variability of H is explained by the combination of four predictors: the annual riverine nitrate load (N), the sea surface temperature in the month preceding stratification (Ts), the amount of semi-labile organic matter accumulated in the sediments (C) and the sea surface temperature during late summer (Tf). Partial regression indicates that the climatic impact on hypoxia is almost as important as that of eutrophication. Accumulation of organic matter in the sediments introduces an important inertia in the recovery process after eutrophication, with a typical timescale of 9.3 yr. Seasonal fluctuations and the heterogeneous spatial distribution complicate the monitoring of bottom hypoxia, leading to contradictory conclusions when the interpretation is done from different sets of data. In particular, it appears that the recovery reported in the literature after 1995 was overestimated due to the use of observations concentrated in areas and months not typically affected by hypoxia. This stresses the urgent need for a dedicated monitoring effort in the Black Sea NWS focused on the areas and months concerned by recurrent hypoxic events.

  • Open Access English
    Authors: 
    Suari, Yair; Dadon-Pilosof, Ayelet; Sade, Tal; Amit, Tal; Gilboa, Merav; Gafny, Sarig; Topaz, Tom; Zedaka, Hadar; Boneh, Shira; Yahel, Gitai;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Long-term, multi-parameter monitoring database that covers physical, chemical, and biological water properties at several stations along a Levantine micro-estuary and its neighboring coastal sea. The data are divided into two separate databases: Monthly surveys of water properties along the estuary and Bi-weekly surveys of water properties at two marine stations.

Advanced search in Research products
Research products
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Searching FieldsTerms
Any field
arrow_drop_down
includes
arrow_drop_down
Include:
The following results are related to European Marine Science. Are you interested to view more results? Visit OpenAIRE - Explore.
959 Research products, page 1 of 96
  • Open Access English
    Authors: 
    Shaviklo, A.; Mozafari, H.; Motamedzadegan, A.; Damavandi-Kamali, N.;

    Tuna processing by-product is estimated at more than 100,000 metric tonnes annually in Iran, which could be a potential source of edible protein in human food. Hence, recovering proteins from tuna by-products is a big achievement in the seafood industry. In this work tuna protein isolates (TPI) were extracted from dark/ red meat using the isoelectric solubilization/ precipitation method. Oxidative stability, biochemical indices and characteristics of the fatty acid composition of TPI (pH 6.5) containing 16.2% protein, 1.2% fat and mixed with a blend of salt and sucrose – as a cryostabilizer - and stored 6 months at -24°C were studied. The levels of peroxide (PV), TBARS, FFA and total volatile basic nitrogen (TVB-N) were significantly increased in TPI without cryostabilizers during the storage time. The results revealed that 22 fatty acids were identified in the light and dark tuna meat and TPI. The fatty acid composition of light and dark muscle of tuna and TPI containing salt and sucrose was the same. However a significant change was observed only in the TPI free from cryostabilizers during frozen storage. The results confirm inhibiting of lipid oxidation due to the incorporation of salt and sucrose to TPI. Published

  • Open Access English
    Authors: 
    Morris, K. J.; Herrera, S.; Gubili, C.; Tyler, P. A.; Rogers, A.; Hauton, C.;
    Project: EC | HERMIONE (226354)

    Despite being an abundant group of significant ecological importance the phylogenetic relationships of the Octocorallia remain poorly understood and very much understudied. We used 1132 bp of two mitochondrial protein-coding genes, nad2 and mtMutS (previously referred to as msh1), to construct a phylogeny for 161 octocoral specimens from the Atlantic, including both Isididae and non-Isididae species. We found that four clades were supported using a concatenated alignment. Two of these (A and B) were in general agreement with the of Holaxonia–Alcyoniina and Anthomastus–Corallium clades identified by previous work. The third and fourth clades represent a split of the Calcaxonia–Pennatulacea clade resulting in a clade containing the Pennatulacea and a small number of Isididae specimens and a second clade containing the remaining Calcaxonia. When individual genes were considered nad2 largely agreed with previous work with MtMutS also producing a fourth clade corresponding to a split of Isididae species from the Calcaxonia–Pennatulacea clade. It is expected these difference are a consequence of the inclusion of Isisdae species that have undergone a gene inversion in the mtMutS gene causing their separation in the MtMutS only tree. The fourth clade in the concatenated tree is also suspected to be a result of this gene inversion, as there were very few Isidiae species included in previous work tree and thus this separation would not be clearly resolved. A~larger phylogeny including both Isididae and non Isididae species is required to further resolve these clades.

  • Open Access English
    Authors: 
    de Kluijver Anna; Soetaert Karline; Schulz Kai Georg; Riebesell Ulf; Bellerby Richard G J; Middelburg Jack J;
    Project: EC | MEECE (212085), EC | EPOCA (211384)

    The potential impact of rising carbon dioxide (CO2) on carbon transfer from phytoplankton to bacteria was investigated during the 2005 PeECE III mesocosm study in Bergen, Norway. Sets of mesocosms, in which a phytoplankton bloom was induced by nutrient addition, were incubated under 1× (~350 μatm), 2× (~700 μatm), and 3× present day CO2 (~1050 μatm) initial seawater and sustained atmospheric CO2 levels for 3 weeks. 13C labelled bicarbonate was added to all mesocosms to follow the transfer of carbon from dissolved inorganic carbon (DIC) into phytoplankton and subsequently heterotrophic bacteria, and settling particles. Isotope ratios of polar-lipid-derived fatty acids (PLFA) were used to infer the biomass and production of phytoplankton and bacteria. Phytoplankton PLFA were enriched within one day after label addition, whilst it took another 3 days before bacteria showed substantial enrichment. Group-specific primary production measurements revealed that coccolithophores showed higher primary production than green algae and diatoms. Elevated CO2 had a significant positive effect on post-bloom biomass of green algae, diatoms, and bacteria. A simple model based on measured isotope ratios of phytoplankton and bacteria revealed that CO2 had no significant effect on the carbon transfer efficiency from phytoplankton to bacteria during the bloom. There was no indication of CO2 effects on enhanced settling based on isotope mixing models during the phytoplankton bloom, but this could not be determined in the post-bloom phase. Our results suggest that CO2 effects are most pronounced in the post-bloom phase, under nutrient limitation.

  • Open Access English
    Authors: 
    Alishahi, M.; Tollabi, M.; Ghorbanpour, M.;

    The success of many vaccines relies on their association with selected adjuvants in order to increase their immunogenicity and ensure long-term protection. Propolis is a natural compound, mostly known for its immunostimulatory properties. In this study the adjuvant effects of propolis in combination with formalin-killed Aeromonas hydrophila vaccine in Common carp (Cyprinus carpio) were evaluated and compared with Freund’s adjuvant. Three hundred juvenile carp (weighing 50.4±3.2 g) were divided randomly into four groups in triplicates. The fish were intraperitonealy injected with A. hydrophila bacterin (A.h) in combination with normal saline (Formalin Killed Bacterin, FKB group), Freund (FKB +F group), and Propolis (FKB +P group) respectively. The control group was injected with normal saline. Serum samples were taken from fish in each group every other week (days 0, 14, 28 and 42) of the experiment and immunological parameters including anti A. hydrophila antibody titer, serum lysozyme and antibacterial activity, complement activity, Nitro blue tetrazolium activity and serum total protein and globulin were compared among the groups. At the end of study the remaining fish in each group were challenged with virulent A. hydrophila and mortality was recorded for 10 days and Relative Percentage Survival (RPS) was calculated and compared among the groups. Results showed that although antibody titer and most of none specific immune responses increased in groups 2 and 3 compare to control group (p0.05). Besides no significant change was observed in mortality rate following the challenge in the propolis adjuvanted group compared with the FKB group (p>0.05). According to results, it can be concluded that although propolis as an adjuvant can promote some immune responses of common carp, it can't affect efficacy of vaccine and Ab titer of injected antigens, so it seems more work is needed to present propolis as a proper candidate for the development of a natural adjuvant in fish vaccines. Published

  • Open Access English
    Authors: 
    Mayer, Kathryn J;
    Publisher: eScholarship, University of California
    Country: United States

    Aerosol-cloud interactions are one of the largest sources of uncertainty in our understanding of the Earth’s climate system. In order to develop better predictive models and understand how the climate will respond to future changes in atmospheric composition, we must determine the sources and nature of aerosols which serve as cloud condensation nuclei (CCN), thus influencing the properties of clouds. Oceans cover 70% of the Earth’s surface and represent a major source of atmospheric aerosols. Sea spray aerosol (SSA) is formed by the action of breaking waves, whereas secondary marine aerosols (SMA) are formed from the oxidation products of gases emitted from the oceans. Biological activity in seawater (i.e. the life, death, and interactions of marine phytoplankton, bacteria, and viruses) can significantly affect the chemical composition of SSA through processing of dissolved organic matter and SMA through the emission of volatile gases. This dissertation investigates the cloud-relevant properties of SSA and SMA generated using ocean-atmosphere simulators in the laboratory, with a specific emphasis on the influence of biological activity in seawater on the properties of these aerosols. For the first time, SMA was produced from the oxidation of the headspace gases of a phytoplankton bloom grown in natural seawater, enabling measurements of its chemical composition and CCN activity. Overall, these studies show that the formation and properties of SMA are much more sensitive to biological activity in seawater than SSA. In addition, the chemical composition of SMA is highly dependent on the extent of photochemical oxidation, with a distinct shift from organic-rich to sulfate-rich composition in response to increased atmospheric aging. This change in SMA composition leads to a significant change in its hygroscopicity. These results suggest that the properties of SMA evolve temporally in the atmosphere, which has implications for CCN concentrations and cloud properties over the oceans.

  • Open Access English
    Authors: 
    Jokinen, Sami A; Virtasalo, Joonas J; Jilbert, Tom; Kaiser, Jérôme; Dellwig, Olaf; Arz, Helge Wolfgang; Hänninen, J; Arppe, Laura; Collander, Miia; Saarinen, Timo;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment. Here we present a 1500-year multiproxy record of near-bottom water redox changes from the coastal zone of the northern Baltic Sea, encompassing the climatic phases of the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), and the Modern Warm Period (MoWP). Our reconstruction shows that although multicentennial climate variability has modulated depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented, and besides gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. Alongside the anthropogenic nutrient input, the progressive deoxygenation since the beginning of the1900s was fueled by the combined effects of gradual shoaling of the basin and warming climate, which amplified sediment focusing and increased the vulnerability to hypoxia. Importantly, the eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s. We find no evidence of similar anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal water quality. Furthermore, this study highlights the need for combined use of sedimentological, ichnological, and geochemical proxies in order to robustly reconstruct subtle redox shifts especially in dynamic, non-euxinic coastal settings with strong seasonal contrasts in the bottom water quality.

  • Open Access English
    Authors: 
    Milzer, G.; Giraudeau, J.; Faust, J.; Knies, J.; Eynaud, F.; Rühlemann, C.;
    Project: EC | CASE (238111)

    Instrumental records from the Norwegian Sea and the Trondheimsfjord show evidence that changes of bottom water temperature and salinity in the fjord are linked to the salinity and temperature variability of the North Atlantic Current (NAC). Changes in primary productivity and salinity in the surface and intermediate water masses in the Trondheimsfjord as well as the fjord sedimentary budget are mainly driven by changes in riverine input. In this study we use 59 surface sediment samples that are evenly distributed in the fjord to examine whether dinocyst assemblages and stable isotope ratios of benthic foraminifera reflect the present-day hydrology and can be used as palaeoceanographic proxies. In general, modern benthic δ18O and δ13C values decrease from the fjord entrance towards the fjord head with lowest values close to river inlets. This is essentially explained by gradients in the amounts of fresh water and terrigenous organic matter delivered from the hinterland. The distribution of benthic δ13C ratios across the fjord is controlled by the origin (terrigenous vs. marine) of organic matter, local topography-induced variability in organic matter flux at the water–sediment interface, and organic matter degradation. The dinocyst assemblages display the variations in hydrography with respect to the prevailing currents, the topography, and the freshwater and nutrient supply from rivers. The strength and depth of the pycnocline in the fjord strongly vary seasonally and thereby affect water mass characteristics as well as nutrient availability, temporally creating local conditions that explain the observed species distribution. Our results prove that dinocyst assemblages and benthic foraminiferal isotopes reliably mirror the complex fjord hydrology and can be used as proxies of Holocene climatic variability.

  • Open Access English
    Authors: 
    Crise, Alessandro; Ribera d’Alcalà, Maurizio; Mariani, Patrizio; Petihakis, George; Robidart, Julie; Iudicone, Daniele; Bachmayer, Ralf; Malfatti, Francesca;
    Project: UKRI | Development and applicati... (NE/N006496/1), EC | JERICO-NEXT (654410), EC | AtlantOS (633211), EC | EMSO-Link (731036)

    In the field of ocean observing, the term of “observatory” is often used without a unique meaning. A clear and unified definition of observatory is needed in order to facilitate the communication in a multidisciplinary community, to capitalize on future technological innovations and to support the observatory design based on societal needs. In this paper, we present a general framework to define the next generation Marine OBservatory (MOB), its capabilities and functionalities in an operational context. The MOB consists of four interconnected components or “gears” (observation infrastructure, cyberinfrastructure, support capacity, and knowledge generation engine) that are constantly and adaptively interacting with each other. Therefore, a MOB is a complex infrastructure focused on a specific geographic area with the primary scope to generate knowledge via data synthesis and thereby addressing scientific, societal, or economic challenges. Long-term sustainability is a key MOB feature that should be guaranteed through an appropriate governance. MOBs should be open to innovations and good practices to reduce operational costs and to allow their development in quality and quantity. A deeper biological understanding of the marine ecosystem should be reached with the proliferation of MOBs, thus contributing to effective conservation of ecosystems and management of human activities in the oceans. We provide an actionable model for the upgrade and development of sustained marine observatories producing knowledge to support science-based economic and societal decisions. Refereed 14.A Manual (incl. handbook, guide, cookbook etc) 2018-09-07

  • Open Access English
    Authors: 
    Capet, A.; Beckers, J.-M.; Grégoire, M.;
    Project: EC | HYPOX (226213)

    The Black Sea northwestern shelf (NWS) is a shallow eutrophic area in which the seasonal stratification of the water column isolates the bottom waters from the atmosphere. This prevents ventilation from counterbalancing the large consumption of oxygen due to respiration in the bottom waters and in the sediments, and sets the stage for the development of seasonal hypoxia. A three-dimensional (3-D) coupled physical–biogeochemical model is used to investigate the dynamics of bottom hypoxia in the Black Sea NWS, first at seasonal and then at interannual scales (1981–2009), and to differentiate its driving factors (climatic versus eutrophication). Model skills are evaluated by a quantitative comparison of the model results to 14 123 in situ oxygen measurements available in the NOAA World Ocean and the Black Sea Commission databases, using different error metrics. This validation exercise shows that the model is able to represent the seasonal and interannual variability of the oxygen concentration and of the occurrence of hypoxia, as well as the spatial distribution of oxygen-depleted waters. During the period 1981–2009, each year exhibits seasonal bottom hypoxia at the end of summer. This phenomenon essentially covers the northern part of the NWS – which receives large inputs of nutrients from the Danube, Dniester and Dnieper rivers – and extends, during the years of severe hypoxia, towards the Romanian bay of Constanta. An index H which merges the aspects of the spatial and temporal extension of the hypoxic event is proposed to quantify, for each year, the intensity of hypoxia as an environmental stressor. In order to explain the interannual variability of H and to disentangle its drivers, we analyze the long time series of model results by means of a stepwise multiple linear regression. This statistical model gives a general relationship that links the intensity of hypoxia to eutrophication and climate-related variables. A total of 82% of the interannual variability of H is explained by the combination of four predictors: the annual riverine nitrate load (N), the sea surface temperature in the month preceding stratification (Ts), the amount of semi-labile organic matter accumulated in the sediments (C) and the sea surface temperature during late summer (Tf). Partial regression indicates that the climatic impact on hypoxia is almost as important as that of eutrophication. Accumulation of organic matter in the sediments introduces an important inertia in the recovery process after eutrophication, with a typical timescale of 9.3 yr. Seasonal fluctuations and the heterogeneous spatial distribution complicate the monitoring of bottom hypoxia, leading to contradictory conclusions when the interpretation is done from different sets of data. In particular, it appears that the recovery reported in the literature after 1995 was overestimated due to the use of observations concentrated in areas and months not typically affected by hypoxia. This stresses the urgent need for a dedicated monitoring effort in the Black Sea NWS focused on the areas and months concerned by recurrent hypoxic events.

  • Open Access English
    Authors: 
    Suari, Yair; Dadon-Pilosof, Ayelet; Sade, Tal; Amit, Tal; Gilboa, Merav; Gafny, Sarig; Topaz, Tom; Zedaka, Hadar; Boneh, Shira; Yahel, Gitai;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science

    Long-term, multi-parameter monitoring database that covers physical, chemical, and biological water properties at several stations along a Levantine micro-estuary and its neighboring coastal sea. The data are divided into two separate databases: Monthly surveys of water properties along the estuary and Bi-weekly surveys of water properties at two marine stations.