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  • 1
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    The dark portion of the Mediterranean Sea is a bioreactor of organic matter cycling (2012)
    Wiley
    Details
    Publication Date: 2012-05-17
    Description: Total prokaryotic abundance, prokaryotic heterotrophic production and enzymatic activities were investigated in epi-, meso- and bathypelagic waters along a longitudinal transect covering the entire Mediterranean Sea. The prokaryotic production and enzymatic activities in deep waters were among the highest reported worldwide at similar depths, indicating that the peculiar physico-chemical characteristics of the Mediterranean Sea, characterized by warm temperatures (typically 13°C also at abyssal depths), support high rates of organic carbon degradation and incorporation by prokaryotic assemblages. The higher trophic conditions in the epipelagic waters of the Western basin resulted in significantly higher prokaryotic production and enzymatic activities rates than in the Central-Eastern basin. While all of the variables decreased significantly from epi- to meso- and bathypelagic waters, cell-specific hydrolytic activity and cell-specific carbon production significantly increased. In addition, the deep-water layers were characterized by low half-saturation constants (Km) of all enzymatic activities. These findings suggest that prokaryotic assemblages inhabiting the dark portion of the Mediterranean Sea are able to channel degraded carbon into biomass in a very efficient way, and that prokaryotic assemblages of the deep Mediterranean waters work as a “bioreactor” of organic matter cycling. Since prokaryotic production and enzymatic activities in deep water masses were inversely related with oxygen concentration, we hypothesize a tight link between prokaryotic metabolism and oxygen consumption. As climate change is increasing deep-water temperatures, the predicted positive response of prokaryotic metabolism to temperature increases may accelerate oxygen depletion of deep Mediterranean waters, with cascade consequences on carbon cycling and biogeochemical processes on the entire deep basin.
    Print ISSN: 0886-6236
    Electronic ISSN: 1944-9224
    Topics: Biology , Chemistry and Pharmacology , Geography , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    STRUCTURE AND INTERACTIONS WITHIN THE PELAGIC MICROBIAL FOOD WEB (FROM VIRUSES TO MICROPLANKTON) ACROSS ENVIRONMENTAL GRADIENTS IN THE MEDITERRANEAN SEA (2013)
    Wiley
    Details
    Publication Date: 2013-10-16
    Description: ABSTRACT [1]  We have here investigated the structure of the pelagic microbial food web and quantified the carbon fluxes from viruses to microplankton along trophic gradients in the Mediterranean Sea. To explore the complex trophic pathways of the pelagic food web, we conducted independent and replicated experiments to measure: (i) predation on prokaryotes by microzooplankton; (ii) predation on prokaryotes by heterotrophic nanoflagellates; (iii) virus-induced prokaryotic mortality; and (iv) microzooplankton grazing on nanoplankton and microphytoplankton. Our study covered more than 5000 km, from the Atlantic Ocean to the Levantine basin, and from conditions of high primary production and nutrient availability to ultra-oligotrophic and phosphate-limited waters. Microphytoplankton abundance and biomass were typically scarce across the entire Mediterranean basin, with almost negligible levels in the eastern part. Also, nanoplankton biomass was typically low. Conversely, prokaryotes, and particularly the heterotrophic components, were abundant and represented the only significant food source for both nanoplankton and microplankton grazers. Viral infections were not the primary agents of prokaryotic mortality, but in some areas, such as the Ligurian Sea, they had a key role in prokaryotic dynamics. The scenario depicted in this study in summer reveals the pivotal role of microzooplankton in the pelagic food web of the Mediterranean Sea, with a key role in the potential transfer of biomass to higher trophic levels. We also show that converse to theoretical expectations, the microbial food web was relatively complex under the mesotrophic conditions (Atlantic and western Mediterranean), and was much more simplified in the ultra-oligotrophic conditions of the eastern Mediterranean.
    Print ISSN: 0886-6236
    Electronic ISSN: 1944-9224
    Topics: Biology , Chemistry and Pharmacology , Geography , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Major viral impact on the functioning of benthic deep-sea ecosystems (2008)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2008-08-30
    Description: Viruses are the most abundant biological organisms of the world's oceans. Viral infections are a substantial source of mortality in a range of organisms-including autotrophic and heterotrophic plankton-but their impact on the deep ocean and benthic biosphere is completely unknown. Here we report that viral production in deep-sea benthic ecosystems worldwide is extremely high, and that viral infections are responsible for the abatement of 80% of prokaryotic heterotrophic production. Virus-induced prokaryotic mortality increases with increasing water depth, and beneath a depth of 1,000 m nearly all of the prokaryotic heterotrophic production is transformed into organic detritus. The viral shunt, releasing on a global scale approximately 0.37-0.63 gigatonnes of carbon per year, is an essential source of labile organic detritus in the deep-sea ecosystems. This process sustains a high prokaryotic biomass and provides an important contribution to prokaryotic metabolism, allowing the system to cope with the severe organic resource limitation of deep-sea ecosystems. Our results indicate that viruses have an important role in global biogeochemical cycles, in deep-sea metabolism and the overall functioning of the largest ecosystem of our biosphere.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Danovaro, Roberto -- Dell'Anno, Antonio -- Corinaldesi, Cinzia -- Magagnini, Mirko -- Noble, Rachel -- Tamburini, Christian -- Weinbauer, Markus -- England -- Nature. 2008 Aug 28;454(7208):1084-7. doi: 10.1038/nature07268.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Marine Science, Faculty of Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy. r.danovaro@univpm.it〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18756250" target="_blank"〉PubMed〈/a〉
    Keywords: Biomass ; Carbon/metabolism ; *Ecosystem ; Geologic Sediments/virology ; Heterotrophic Processes ; Hydrostatic Pressure ; Microbial Viability ; Oceans and Seas ; Prokaryotic Cells/cytology/metabolism/virology ; Seawater/*virology ; *Virus Physiological Phenomena ; Viruses/isolation & purification/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Extracellular DNA plays a key role in deep-sea ecosystem functioning (2005)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2005-10-01
    Description: The ecological role and biogeochemical relevance of extracellular DNA in the oceanic sediments are unknown. Our global estimates indicate that up to 0.45 gigatons of extracellular DNA are present in the top 10 centimeters of deep-sea sediments, representing the largest reservoir of DNA in the world oceans. We demonstrate that extracellular DNA accounts for about one fifth of the total organic phosphorus regeneration and provides almost half of the prokaryotic demand for organic phosphorus. It therefore plays a key role in deep-sea ecosystem functioning on a global scale.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dell'Anno, Antonio -- Danovaro, Roberto -- New York, N.Y. -- Science. 2005 Sep 30;309(5744):2179.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Marine Science, Faculty of Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16195451" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomass ; Carbon/metabolism ; DNA/*analysis/chemistry/*metabolism ; Deoxyribonucleases/metabolism ; *Ecosystem ; Geologic Sediments/chemistry ; Nitrogen/metabolism ; Oceans and Seas ; Phosphorus/*analysis ; Pigments, Biological/analysis ; Prokaryotic Cells/*metabolism ; *Seawater
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Protect the deep sea (2014)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2014-01-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barbier, Edward B -- Moreno-Mateos, David -- Rogers, Alex D -- Aronson, James -- Pendleton, Linwood -- Danovaro, Roberto -- Henry, Lea-Anne -- Morato, Telmo -- Ardron, Jeff -- Van Dover, Cindy L -- England -- Nature. 2014 Jan 23;505(7484):475-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24459714" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anthozoa ; Aquatic Organisms ; Atlantic Ocean ; Biodiversity ; *Conservation of Natural Resources/economics/methods/trends ; *Ecology/economics/methods/trends ; *Ecosystem ; Fisheries/economics ; *Oceans and Seas
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 6
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    [Policy Forum] An ecosystem-based deep-ocean strategy (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2017-02-03
    Description: Increasing exploration and industrial exploitation of the vast and fragile deep-ocean environment for a wide range of resources (e.g., oil, gas, fisheries, new molecules, and soon, minerals) raises global concerns about potential ecological impacts (1–3). Multiple impacts on deep-sea ecosystems (〉200 m below sea level; ∼65% of the Earth's surface is covered by deep ocean) caused by human activities may act synergistically and span extensive areas. Cumulative impacts could eventually cause regime shifts and alter deep-ocean life-support services, such as the biological pump or nutrient recycling (2, 4, 5). Although international law and national legislation largely ignore the deep sea's critical role in the functioning and buffering of planetary systems, there are promising developments in support of deep-sea protection at the United Nations and the International Seabed Authority (ISA). We propose a strategy that builds from existing infrastructures to address research and monitoring needs to inform governments and regulators. Authors: R. Danovaro, J. Aguzzi, E. Fanelli, D. Billett, K. Gjerde, A. Jamieson, E. Ramirez-Llodra, C. R. Smith, P. V. R. Snelgrove, L. Thomsen, C. L. Van Dover
    Keywords: Ocean Governance
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 7
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    Biodiversity and trophic structure of nematode assemblages in seagrass systems: evidence for a coupling with changes in food availability (2002)
    Springer
    Details
    Publication Date: 2002-10-01
    Print ISSN: 0025-3162
    Electronic ISSN: 1432-1793
    Topics: Biology
    Published by Springer
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  • 8
    Electronic Resource
    Electronic Resource
    Decomposition of faecal matter and somatic tissue of Mytilus galloprovincialis: changes in organic matter composition and microbial succession (1994)
    Springer
    Marine biology 119 (1994), S. 375-384 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variations in the biochemical composition of pseudo-faeces and faeces egested by Mytilus galloprovincialis (Lamarck) and in detritus derived from the somatic tissue of mussels during the decomposition process were investigated by means of two intensive experiments. During the degradation process, the biochemical composition of pseudo-faeces and faeces showed a clear increase in protein content related to the microbial colonization. Changes also occurred in the biochemical composition of particulate organic matter (POM) in the surrounding water due to faecal matter decomposition, heterotrophic utilization and conversion of particulate carbohydrates and proteins to the dissolved pool. The study of production and heterotrophic utilization of the POM derived from the somatic tissue of M. galloprovincialis collected in the Gulf of Tigullio, Italy in 1990 indicates that this kind of material is rapidly decomposable and largely available for benthic consumers. Bacteria utilized selectively the different compounds, and proteins proved to be the most suitable substrate for bacterial growth. The input of organic detritus into the experimental system resulted in an enhancement of bacterial activity and consequently of the RNA/DNA ratio. Bacterial DNA accounted on average for 17% of particulate DNA. During decomposition processes, nutrient release was about ten times higher than the value calculated from individual excretion rates, indicating that mussel beds may be important sites for nutrient regeneration. Carbon conversion efficiency for bacteria growing on faecal matter was, on average, 17.2%. The potential importance of faecal output and bacterial production as a carbon resource for benthic communities near mussel culture areas is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347534
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  • 9
    Electronic Resource
    Electronic Resource
    Meiofauna response to a dynamic river plume front (2000)
    Springer
    Marine biology 137 (2000), S. 359-370 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The benthic response to a plume front was studied in two areas of the northern Adriatic (Mediterranean Sea) differently influenced by the Po River freshwater input. Sediment samples were collected in June 1996 and February 1997 from 12 stations. The adopted sampling strategy was able to identify the front line in real time by satellite images and to locate sampling stations along an inner–outer plume gradient in order to cover the benthic area beneath the river plume, where enhanced biological production was expected, and open-sea sediments not directly influenced by freshwater inputs. Meiofaunal parameters were compared to the physical conditions and to phytodetritus inputs, organic matter accumulation and bacterial secondary production. The sediments of the Adriatic Sea were characterised by high concentrations of phytopigments (0.6 to 13.9 μg g−1 for chlorophyll a and 1.2 to 17.7 μg g−1 for phaeopigments) and biopolymeric organic carbon (0.15 to 3.02 mg g−1). The plume system extended for a large sector of the northern Adriatic. In the northern area, a large and highly dynamic plume area was coupled with a sediment organic matter concentration significantly higher than in open-sea sediments. In the southern sector, where the plume area and the front line did not change markedly during the year, plume–benthic coupling was evident only in the sediments beneath the front, and corresponded to phaeopigment accumulation. Bacterial parameters and secondary production were high and significantly higher in the frontal area than at open-sea stations. Meiofauna density (1342 to 8541 ind. 10 cm−2) did not change either by season or between areas and was significantly correlated with phaeopigments and bacterial secondary production. Meiofauna displayed different responses to plume inputs in the two sampling areas. In the northern sector, meiofauna density was coupled with organic matter distribution and displayed highest values beneath the plume. In the southern sector, the densities of copepods, turbellarians and kinorhynchs displayed highest values under the front in summer, and the same applied to total meiofauna density in winter. Juvenile decapods and copepod nauplii significantly increased their densities in sediments beneath the front. Data presented in the present study suggest that plume inputs and frontal systems, enhancing phytodetritus accumulation and benthic bacterial response, might influence density, composition and distribution of meiofaunal assemblages. As river plumes are highly variable systems affecting the trophic characteristics of the sediments underneath, their dynamics should be considered when analysing mesoscale spatial changes of meiofaunal assemblages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270000353
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  • 10
    Electronic Resource
    Electronic Resource
    Seasonal changes of benthic bacteria in a seagrass bed (Posidonia oceanica) of the Ligurian Sea in relation to origin, composition and fate of the sediment organic matter (1994)
    Springer
    Marine biology 119 (1994), S. 489-500 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variations in number and biomass of benthic bacteria were examined in the surface sediments of a Mediterranean seagrass bed [Posidonia oceanica (L.) Delile] in the Gulf of Marconi (northwestern Mediterranean Sea) from 1990 to 1991. The annual dynamics of benthic bacterial density and biomass were compared to changes in elemental (organic C and total N) and biochemical (lipids, proteins, carbohydrates) composition of sediment organic matter, as well as to microphytobenthic biomass, dissolved inorganic nutrients and ATP. Bacterial densities exhibited marked seasonal variations (5.12 to 322.7x108 cells g-1 sediment dry wt) with highest values in late spring. Bacterial standing stocks (15.8 to 882.33 μg C g-1 of sediment dry wt) were high. Bacterial biomass did not correlate with organic C, total N or to specific biochemical components, but correlated significantly with chlorophyll a, ATP and porewater phosphate concentrations. There is evidence that benthic bacteria were responding to variations of algal biomass. Bacterial biomass accounted, on average, for 30% of total living carbon (calculated on the basis of the ATP concentrations) and 8.4% of total organic carbon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00354310
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