Organic Matter Productivity and Preservation Signals, Lake Bafa Basin (Aegean Sea, Turkey)

The effect of Black Sea Water (BSW) inputs on the North Aegean Sea productivity and food web dynamics was investigated, by means of sensitivity simulations, investigating the effect of the inflowing BSW, in terms of inorganic nutrients and dissolved organic matter. The model used has been successfully applied in the area in the past and extensively presented. Considering the importance of the microbial loop in the ecosystem functioning, the role of the dissolved organics and in order to achieve a more realistic representation of the Dissolved Organic Matter pool, the bacteria sub-model was appropriately revised. The importance of the microbial loop is highlighted by the carbon fluxes where almost 50% of carbon is channelled within it. The impact of dissolved organic matter (DOM) (in the inflowing to the Aegean Sea, BSW) appears to be stronger than the impact of dissolved inorganic nutrients, showing a more extended effect over the N Aegean. Bacterial production and biomass is more strongly affected in the simulations by modified DOM, unlike phytoplankton biomass and production, which are more dependent on the inflowing nutrients and particularly phosphorus (inorganic and dissolved organic). In the phytoplankton composition, the dinoflagellates appear to be mostly affected, being favoured by higher nutrient availability at the expense of all other groups, particularly picoplankton, indicating a shift to a more classical food chain.

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Identification of 16S Ribosomal DNA-Defined Bacterial Populations at a Shallow Submarine Hydrothermal Vent near Milos Island (Greece)

Applied and Environmental Microbiology ◽

10.1128/aem.66.7.3102-3109.2000 ◽

2000 ◽

Vol 66 (7) ◽

pp. 3102-3109 ◽

Cited By ~ 74

Author(s):

Stefan M. Sievert ◽

Jan Kuever ◽

Gerard Muyzer

Keyword(s):

Phylogenetic Analysis ◽

Organic Matter ◽

Hydrothermal Vent ◽

Bacterial Community Structure ◽

Aegean Sea ◽

Allochthonous Organic Matter ◽

Bacterial Populations ◽

16S Ribosomal Dna ◽

Spatiotemporal Changes ◽

Bacterial Groups

ABSTRACT In a recent publication (S. M. Sievert, T. Brinkhoff, G. Muyzer, W. Ziebis, and J. Kuever, Appl. Environ. Microbiol. 65:3834–3842, 1999) we described spatiotemporal changes in the bacterial community structure at a shallow-water hydrothermal vent in the Aegean Sea near the isle of Milos (Greece). Here we describe identification and phylogenetic analysis of the predominant bacterial populations at the vent site and their distribution at the vent site as determined by sequencing of DNA molecules (bands) excised from denaturing gradient gels. A total of 36 bands could be sequenced, and there were representatives of eight major lineages of the domainBacteria. Cytophaga-Flavobacterium andAcidobacterium were the most frequently retrieved bacterial groups. Less than 33% of the sequences exhibited 90% or more identity with cultivated organisms. The predominance of putative heterotrophic populations in the sequences retrieved is explained by the input of allochthonous organic matter at the vent site.

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High oxygen consumption rates in the deep layers of the North Aegean Sea (eastern Mediterranean)

Mediterranean Marine Science ◽

10.12681/mms.258 ◽

2002 ◽

Vol 3 (1) ◽

pp. 55 ◽

Cited By ~ 7

Author(s):

E. SOUVERMEZOGLOU ◽

E. KRASAKOPOULOU

Keyword(s):

Organic Matter ◽

Oxygen Consumption ◽

Aegean Sea ◽

High Oxygen ◽

Dense Water ◽

The North ◽

Water Formation ◽

Deep Layers ◽

North Aegean ◽

North Aegean Sea

Severe winter meteorological conditions promote dense water formation over the shelves of the North Aegean Sea. The newly formed dense water fills the deep basins of the North Aegean Sea, contributing to their ventilation and the downward transport of organic and inorganic material. The great bathymetric variability imposes limitations on the deep circulation and the communication between the various basins and makes the North Aegean Sea an appropriate area for the monitoring of oxygen consumption in the deep layers. Historical hydrographic data suggest that there was extensive production of dense water in the North Aegean Sea on two occasions during the last decade, the winters of 1987 and 1992-1993. Our data series from August 1986 to September 1989 and from March 1997 to February 1999, permitted us to follow, step by step, the oxygen consumption and the nutrient regeneration in the deep basins of the northern Aegean Sea during these periods of isolation. The organic matter reaching the bottom layer just after the deep water formation event is rich in labile and easily oxidizable material and its decomposition leads to a significant oxygen uptake during the first year of stagnation. The further decomposition of the remaining semi-labile and refractory material turns over on greater time scales, by consuming lesser amounts of oxygen. A more significant oxygen decrease is recorded in the eastern basin (Lemnos Basin) of the North Aegean Trough, than in the central (Athos Basin) and the western (North Sporades Basin) ones and is attributed to the irregular contribution of the Black Sea Water (BSW) to the water masses formed on the different shelves of the North Aegean Sea. Our results and the existing data on the Turkish straits showed that dissolved organic matter is the major constituent responsible for this high oxygen consumption. The slightly different particulate organic carbon fluxes to these depressions play a secondary role.

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Stable carbon isotope deviations in benthic foraminifera as proxy for organic carbon fluxes in the Mediterranean Sea

10.5194/bg-2016-247 ◽

2016 ◽

Author(s):

Marc Theodor ◽

Gerhard Schmiedl ◽

Frans Jorissen ◽

Andreas Mackensen

Keyword(s):

Organic Matter ◽

Transfer Function ◽

Primary Production ◽

Mediterranean Sea ◽

Carbon Isotope ◽

Pore Water ◽

Benthic Foraminifera ◽

Stable Carbon Isotope ◽

Aegean Sea ◽

Stable Carbon

Abstract. We have determined stable carbon isotope ratios of epifaunal and shallow infaunal benthic foraminifera to relate the inferred gradient of pore water δ13CDIC to varying trophic conditions, and to test the potential of developing a transfer function for organic matter flux rates. The data set is based on samples retrieved from a well-defined bathymetric range (400–1500 m water depth) of sub-basins in the western, central and eastern Mediterranean Sea. Regional contrasts in organic matter fluxes and associated δ13CDIC of pore water are recorded by the δ13C difference (Δδ13CUmed-Epi) between the shallow infaunal Uvigerina mediterranea and epifaunal species (Planulina ariminensis, Cibicidoides pachydermus, Cibicides lobatulus). The Δδ13CUmed-Epi values range from −0.46 to −2.13 ‰, with generally higher offsets at more eutrophic sites. Because of ontogenetic shifts in the δ13C signal of U. mediterranea of up to 1.04 ‰, only tests larger than 600 µm were used for the quantitative environmental evaluation. The measured δ13C deviations are related to site-specific differences in microhabitat, depth of the principal redox boundary, and TOC content. The Δδ13CUmed-Epi values reveal a consistent relation to Corg fluxes estimated from satellite-derived surface water primary production in open-marine settings of the Alboran Sea, Mallorca Channel, Strait of Sicily and southern Aegean Sea. In contrast, Δδ13CUmed-Epi values in areas affected by intense resuspension and riverine organic matter sources of the northern to central Aegean Sea and the canyon systems of the Gulf of Lions suggest higher Corg fluxes compared to the values based on recent surface primary production. Considering the regional biases and uncertainties, a first Δδ13CUmed-Epi based transfer function for Corg fluxes could be established for the Mediterranean Sea.

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