scholarly journals Αλλαγές στις θαλάσσιες βακτηριακές κοινότητες σε συνθήκες εμπλουτισμού με θρεπτικά

2014 ◽  
Author(s):  
Στυλιανός Φοδελιανάκης
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Nutrient Enrichment ◽  
Eastern Mediterranean ◽  
Community Diversity ◽  
Coastal Sediment ◽  
Common Source ◽  
Composition And Structure ◽  
Taxonomic Groups ◽  
Bacterioplankton Communities

Nutrient enrichment is a common source of disturbance for marineecosystems. A prerequisite for the prediction of the effects of nutrient enrichment atthe ecosystem level is the understanding of the ecological mechanisms governingbacterioplankton communities, due to their high affinity with nutrients. The aim ofthis thesis was to examine changes in the composition and structure ofbacterioplankton communities of the water column and coastal sediment undernutrient enrichment. Three studies were conducted for that purpose: two in closedexperimental conditions and one examining changes in situ. In the first two studies,changes in the water column bacterioplankton communities were examined after Paddition and in nutrient enriched habitats, respectively. In the third study, changes inthe communities of coastal sediment were examined with and without the additionof organic matter and aeration of the water column. The main conclusions from theresults of this thesis were:a) Bacterioplankton communities of the Eastern Mediterranean show a high degreeof resistance to short-term P addition, although their biomass and production islimited by P.b) Five abundant taxonomic groups showed a similar pattern of change across threedifferent nutrient enriched habitats. These groups could be potentially used asindicators for monitoring nutrient enrichment at the water column.c) After incubation under presence or absence of organic enrichment, sedimentbacterial communities originating from different habitats clustered based on theincubation conditions rather than on the area of origin. That occurred faster for twoout of the three areas, where the amount of organic matter in the sediment wasinitially higher and bacterial community diversity was lower. These results indirectlysupport the theory of Baas-Becking that "everything is everywhere but theenvironment selects" and the positive correlation between diversity and communitystability.

scholarly journals Spatial Distribution of Arctic Bacterioplankton Abundance Is Linked to Distinct Water Masses and Summertime Phytoplankton Bloom Dynamics (Fram Strait, 79°N)

2021 ◽  
Vol 12 ◽  
Author(s):  
Magda G. Cardozo-Mino ◽  
Eduard Fadeev ◽  
Verena Salman-Carvalho ◽  
Antje Boetius
Keyword(s):  
Water Column ◽  
Phytoplankton Bloom ◽  
Standing Stock ◽  
The Arctic ◽  
Fram Strait ◽  
Arctic Water ◽  
Entire Water Column ◽  
Taxonomic Groups ◽  
Card Fish ◽  
Bacterioplankton Communities

The Arctic is impacted by climate warming faster than any other oceanic region on Earth. Assessing the baseline of microbial communities in this rapidly changing ecosystem is vital for understanding the implications of ocean warming and sea ice retreat on ecosystem functioning. Using CARD-FISH and semi-automated counting, we quantified 14 ecologically relevant taxonomic groups of bacterioplankton (Bacteria and Archaea) from surface (0–30 m) down to deep waters (2,500 m) in summer ice-covered and ice-free regions of the Fram Strait, the main gateway for Atlantic inflow into the Arctic Ocean. Cell abundances of the bacterioplankton communities in surface waters varied from 105 cells mL–1 in ice-covered regions to 106 cells mL–1 in the ice-free regions. Observations suggest that these were overall driven by variations in phytoplankton bloom conditions across the Strait. The bacterial groups Bacteroidetes and Gammaproteobacteria showed several-fold higher cell abundances under late phytoplankton bloom conditions of the ice-free regions. Other taxonomic groups, such as the Rhodobacteraceae, revealed a distinct association of cell abundances with the surface Atlantic waters. With increasing depth (>500 m), the total cell abundances of the bacterioplankton communities decreased by up to two orders of magnitude, while largely unknown taxonomic groups (e.g., SAR324 and SAR202 clades) maintained constant cell abundances throughout the entire water column (ca. 103 cells mL–1). This suggests that these enigmatic groups may occupy a specific ecological niche in the entire water column. Our results provide the first quantitative spatial variations assessment of bacterioplankton in the summer ice-covered and ice-free Arctic water column, and suggest that further shift toward ice-free Arctic summers with longer phytoplankton blooms can lead to major changes in the associated standing stock of the bacterioplankton communities.

scholarly journals Spatial dynamics in Arctic bacterioplankton community densities are strongly linked to distinct physical and biological processes (Fram Strait, 79°N)

2020 ◽  
Author(s):  
Magda G. Cardozo Mino ◽  
Eduard Fadeev ◽  
Verena Salman-Carvalho ◽  
Antje Boetius
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Phytoplankton Bloom ◽  
Standing Stock ◽  
The Arctic ◽  
Fram Strait ◽  
Entire Water Column ◽  
Free Region ◽  
Taxonomic Groups ◽  
Bacterioplankton Communities

AbstractThe Arctic is impacted by climate warming faster than any other oceanic region on Earth. Assessing the baseline of microbial communities in this rapidly changing ecosystem is vital for understanding the imminent implications of Arctic warming and sea ice retreat on ecosystem functioning. Using CARD-FISH and semi-automated counting, we quantified 14 ecologically relevant taxonomic groups of bacterioplankton (Bacteria and Archaea) from surface (0– 30 m) down to deep waters (2500 m) in summerly ice-covered and ice-free regions of the Fram Strait, the main gateway for Atlantic inflow into the Arctic Ocean. Cell abundances of the bacterioplankton communities in surface waters varied from 105 cells mL−1 in ice-covered region to 106 cells mL−1 in the ice-free region and were overall driven by variations in phytoplankton bloom conditions across the Strait. In surface waters the bacterial classes Bacteroidia and Gammaproteobacteria showed several-fold higher cell abundances under late phytoplankton bloom conditions of the ice-free regions. Other taxonomic groups, such as the Rhodobacteraceae, revealed a distinct association of cell abundances with the surface Atlantic waters. With depth (> 500 m) the total cell abundances of the bacterioplankton communities decreased by one to two orders of magnitude, while largely unknown taxonomic groups (e.g., SAR324 and SAR202 clades) maintained constant cell abundances throughout the entire water column (103 cells mL−1). This suggests that some enigmatic taxonomic groups may occupy a specific ecological niche in the entire water column. Our results provide the first quantitative spatial variations assessment of bacterioplankton in summerly ice-covered and ice-free Arctic water column, and suggest that further shift towards ice-free Arctic summers with longer phytoplankton blooms can lead to major changes in the associated standing stock of the bacterioplankton communities.

scholarly journals Quantity and biochemical composition of particulate organic matter in a highly trawled area (Thermaikos Gulf, Eastern Mediterranean Sea)

2015 ◽  
Vol 6 (1/2) ◽  
Author(s):  
Antonio Pusceddu ◽  
Silvia Bianchelli ◽  
Roberto Danovaro
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Water Column ◽  
Particulate Organic Matter ◽  
Biochemical Composition ◽  
Eastern Mediterranean ◽  
Sediment Resuspension ◽  
Natural Sediment ◽  
Bottom Trawling ◽  
Bioavailable Fraction

Bottom trawling represents nowadays one of the most severe anthropogenic disturbances at sea, and determines large impacts on benthic communities and processes. Bottom trawling determines also local sediment resuspension and the effects of the injection of large amounts of surface sediments into the water column have been repeatedly investigated. Few studies have assessed the consequences of sediment resuspension caused by bottom trawling on the quantity, biochemical composition and bioavailability of suspended organic particles and how these eventually rival those exerted by natural storms. To provide insights on this poorly addressed issue, we investigated concentrations and biochemical composition of total and enzymatically digestible pools of particulate organic matter (POM) in the Thermaikos Gulf (Mediterranean Sea) under calm sea conditions, during intensive trawling activities, and after a severe storm. We show here that sediment resuspension caused by trawling can cause large effects on POM quantity, biochemical composition and bioavailability. Both during trawling and after the storm, the relative importance of the carbohydrate pools increased (in the upper water column) and the total lipid concentrations decreased (in the intermediate and bottom layers) when compared to values measured during calm conditions. These results would suggest that bottom trawling could inject in the upper water column POM pools more refractory in nature (<em>e.g</em>., carbohydrates) than those present in calm or after-storm conditions. By contrast, we show also that the bioavailable fraction of biopolymeric C increased significantly during trawling in the upper water column of the shallowest stations and in the bottom water column layer of the deepest ones. These results provide evidence that bottom trawling can influence the overall trophic status of coastal waters, exerting effects similar or stronger than those caused by natural storms, though of variable amplitude depending on the water depth. Since bottom trawling is carried out worldwide and natural storms at sea can be frequent and intense, we claim for the need of assessing new adapting management strategies of bottom trawling in order to mitigate the synergistic impacts of anthropogenic and natural sediment resuspension on coastal biogeochemical cycles.

scholarly journals The Pattern of Change in the Abundances of Specific Bacterioplankton Groups Is Consistent across Different Nutrient-Enriched Habitats in Crete

2014 ◽  
Vol 80 (13) ◽  
pp. 3784-3792 ◽  
Author(s):  
Stilianos Fodelianakis ◽  
Nafsika Papageorgiou ◽  
Paraskevi Pitta ◽  
Panagiotis Kasapidis ◽  
Ioannis Karakassis ◽  
...  
Keyword(s):  
Nutrient Enrichment ◽  
Anthropogenic Activities ◽  
North Coast ◽  
Common Source ◽  
Content Type ◽  
Dissolved Nitrogen ◽  
The North ◽  
Change Pattern ◽  
Α Diversity ◽  
Taxonomic Groups

ABSTRACTA common source of disturbance for coastal aquatic habitats is nutrient enrichment through anthropogenic activities. Although the water column bacterioplankton communities in these environments have been characterized in some cases, changes in α-diversity and/or the abundances of specific taxonomic groups across enriched habitats remain unclear. Here, we investigated the bacterial community changes at three different nutrient-enriched and adjacent undisturbed habitats along the north coast of Crete, Greece: a fish farm, a closed bay within a town with low water renewal rates, and a city port where the level of nutrient enrichment and the trophic status of the habitat were different. Even though changes in α-diversity were different at each site, we observed across the sites a common change pattern accounting for most of the community variation for five of the most abundant bacterial groups: a decrease in the abundance of thePelagibacteraceaeand SAR86 and an increase in the abundance of theAlteromonadaceae,Rhodobacteraceae, andCryomorphaceaein the impacted sites. The abundances of the groups that increased and decreased in the impacted sites were significantly correlated (positively and negatively, respectively) with the total heterotrophic bacterial counts and the concentrations of dissolved organic carbon and/or dissolved nitrogen and chlorophyll α, indicating that the common change pattern was associated with nutrient enrichment. Our results provide anin situindication concerning the association of specific bacterioplankton groups with nutrient enrichment. These groups could potentially be used as indicators for nutrient enrichment if the pattern is confirmed over a broader spatial and temporal scale by future studies.

scholarly journals Speciation of organosulfur compounds in carbonaceous chondrites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander Zherebker ◽  
Yury Kostyukevich ◽  
Dmitry S. Volkov ◽  
Ratibor G. Chumakov ◽  
Lukas Friederici ◽  
...  
Keyword(s):  
Organic Matter ◽  
Analytical Techniques ◽  
Ion Cyclotron Resonance ◽  
Organosulfur Compounds ◽  
Low Oxygen ◽  
Fticr Ms ◽  
Insoluble Organic Matter ◽  
Composition And Structure ◽  
Extractable Fraction ◽  
The Individual

AbstractDespite broad application of different analytical techniques for studies on organic matter of chondrite meteorites, information about composition and structure of individual compounds is still very limited due to extreme molecular diversity of extraterrestrial organic matter. Here we present the first application of isotopic exchange assisted Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for analysis of alkali extractable fraction of insoluble organic matter (IOM) of the Murchison and Allende meteorites. This allowed us to determine the individual S-containing ions with different types of sulfur atoms in IOM. Thiols, thiophenes, sulfoxides, sulfonyls and sulfonates were identified in both samples but with different proportions, which contribution corroborated with the hydrothermal and thermal history of the meteorites. The results were supported by XPS and thermogravimetric analysis coupled to FTICR MS. The latter was applied for the first time for analysis of chondritic IOM. To emphasize the peculiar extraterrestrial origin of IOM we have compared it with coal kerogen, which is characterized by the comparable complexity of molecular composition but its aromatic nature and low oxygen content can be ascribed almost exclusively to degradation of biomacromolecules.

The Metazoan Meiofauna in Its Biogeochemical Environment: The Case of an Antarctic Coastal Sediment

1998 ◽  
Vol 78 (2) ◽  
pp. 411-434 ◽  
Author(s):  
S. Vanhove ◽  
H.J. Lee ◽  
M. Beghyn ◽  
D. Van Gansbeke ◽  
S. Brockington ◽  
...  
Keyword(s):  
Organic Matter ◽  
Standing Stock ◽  
Austral Summer ◽  
Fine Sand ◽  
Coastal Sediment ◽  
Feeding Guild ◽  
Fresh Organic Matter ◽  
Benthic Environment ◽  
Metazoan Meiofauna ◽  
Deposit Feeding

The metazoan meiobenthos was investigated in an Antarctic coastal sediment (Factory Cove, Signy Island, Antarctica). The fine sands contained much higher abundances compared to major sublittoral sediments worldwide. Classified second after Narrangansett Bay (North Atlantic) they reached numbers of 13 × 106ind m-2. The meiofauna was highly abundant in the surface layers, but densities decreased sharply below 2 cm. Vertical profiles mirrored steep gradients of microbiota, chloropigments and organic matter and were coincident with chemical stratification. Spatial patchiness manifested especially in the surface layer. Nematodes dominated (up to 90%), andAponema, Chromctdorita, Diplolaimella, Daptonema, MicrolaimusandNeochromadoraconstituted almost the entire community. Overall, the nematode fauna showed a strong similarity with fine sand communities elsewhere. The dominant trophic strategies were epistrarum and non-selective deposit feeding, but the applied classification for feeding guild structure of the nematodes of Factory Cove is discussed. High standing stock, low diversity and shallow depth distribution may have occurred because of the high nutritive (chlorophyll exceeded lOOOmgm-2and constituted almost 50% of the organic pool) and reductive character of the benthic environment. These observations must have originated from the substantial input of fresh organic matter from phytoplankton and microphytobenthic production, typical for an Antarctic coastal ecosystem during the austral summer.

Effect of extremely severe winters on under-ice phytoplankton development in a mesotrophic lake (Eastern Poland)

2014 ◽  
Vol 43 (2) ◽  
Author(s):  
Władysława Wojciechowska ◽  
Tomasz Lenard
Keyword(s):  
Water Column ◽  
Dominant Species ◽  
Biomass Concentration ◽  
Thermal Conditions ◽  
Ice Cover ◽  
Abundant Species ◽  
Blue Green Algae ◽  
Cyanobacteria And Algae ◽  
Taxonomic Groups ◽  
The Vertical Distribution

AbstractThe research was carried out in a mesotrophic and dimictic lake during winters with ice cover. In the last forty years, the development of phytoplankton was analyzed in five extreme winter seasons. The studies of phytoplankton characteristics in the water column took into account values of biomass, concentration of chlorophyll-a and species composition, including dominant species. Differences in the vertical distribution of flagellate and non-flagellate species belonging to cyanobacteria and algae were analyzed in the gradient of light and thermal conditions. The phytoplankton biomass was low and vertically differentiated, with the lowest values at the deeper part of the water column. Flagellate species from the group of Cryptophyceae, Chrysophyceae and Dinophyceae were most abundant. Species biodiversity was low but every winter the dominant species represented different taxonomic groups. In some periods, larger non-motile phytoplankton species from green or blue-green algae dominated. The research proved that the development of phytoplankton under the ice cover was limited mainly by light and, to a lesser extent, by temperature.

Pyrite geochemistry and fossil preservation in shales

1985 ◽  
Vol 311 (1148) ◽  
pp. 167-169 ◽  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Sulphate Reduction ◽  
Pore Waters ◽  
Anoxic Waters ◽  
Iron Sulphides ◽  
Diagenetic Reaction ◽  
Fossil Preservation

As emphasized by Dr Seilacher in his introduction to this symposium, and illustrated in the contribution by Mr Martill, some of the most important examples of fossil Lagersätten occur in marine shales of Mesozoic age. Many of the factors that control the types and preservation of fossils are the same as those that affect the authigenic mineralogy and geochemistry of the shales, notably the degree of aeration or stagnation of the water column and the quantity and quality of the organic matter supplied to the sediment. Perhaps the most important diagenetic reaction in marine shales is sulphate reduction by bacteria that are obligate anaerobes. They can operate in anoxic waters or in ‘reducing microenvironments’ (such as concentrations of organic matter, or enclosed voids within shells) in sediments whose pore waters are kept generally oxic by the effects of burrowing organisms. Sulphate is reduced to sulphide and in the presence of reduced iron this can be precipitated as iron sulphides, normally found in ancient sediments in the form of pyrite. Pyrite is thus a key mineral in studying shale diagenesis, for its geochemistry as well as for its direct importance in preserving fossils by replacement of soft-parts (see, for example, Stürmer 1984), of aragonitic shells (see, for example, Fisher 1985) and by forming internal moulds of chambered shells (see, for example, Hudson & Palframan 1969; Hudson 1982).

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