scholarly journals Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)

2014 ◽  
Vol 11 (23) ◽  
pp. 7009-7023 ◽  
Author(s):  
C. Berndmeyer ◽  
V. Thiel ◽  
O. Schmale ◽  
N. Wasmund ◽  
M. Blumenberg
Keyword(s):  
Fatty Acids ◽  
Baltic Sea ◽  
Water Column ◽  
Cyanobacterial Bloom ◽  
Methanogenic Archaea ◽  
Water Layer ◽  
Type I ◽  
Anoxic Zone ◽  
Oxic Zone

Abstract. The water column of the Landsort Deep, central Baltic Sea, is stratified into an oxic, suboxic, and anoxic zone. This stratification controls the distributions of individual microbial communities and biogeochemical processes. In summer 2011, particulate organic matter was filtered from these zones using an in situ pump. Lipid biomarkers were extracted from the filters to establish water-column profiles of individual hydrocarbons, alcohols, phospholipid fatty acids, and bacteriohopanepolyols (BHPs). As a reference, a cyanobacterial bloom sampled in summer 2012 in the central Baltic Sea Gotland Deep was analyzed for BHPs. The biomarker data from the surface layer of the oxic zone showed major inputs from cyanobacteria, dinoflagellates, and ciliates, while the underlying cold winter water layer was characterized by a low diversity and abundance of organisms, with copepods as a major group. The suboxic zone supported bacterivorous ciliates, type I aerobic methanotrophic bacteria, sulfate-reducing bacteria, and, most likely, methanogenic archaea. In the anoxic zone, sulfate reducers and archaea were the dominating microorganisms as indicated by the presence of distinctive branched fatty acids: archaeol and pentamethylicosane (PMI) derivatives, respectively. Our study of in situ biomarkers in the Landsort Deep thus provided an integrated insight into the distribution of relevant compounds and describes useful tracers to reconstruct stratified water columns in the geological record.

scholarly journals Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)

2014 ◽  
Vol 11 (6) ◽  
pp. 9853-9887 ◽  
Author(s):  
C. Berndmeyer ◽  
V. Thiel ◽  
O. Schmale ◽  
N. Wasmund ◽  
M. Blumenberg
Keyword(s):  
Fatty Acids ◽  
Baltic Sea ◽  
Water Column ◽  
Cyanobacterial Bloom ◽  
Methanogenic Archaea ◽  
Water Layer ◽  
Type I ◽  
Biogeochemical Processes ◽  
Anoxic Zone

Abstract. The water column of the Landsort Deep, central Baltic Sea, is stratified into an oxic, suboxic and anoxic zone. This stratification controls the distributions of individual microbial communities and biogeochemical processes. In summer 2011, particulate organic matter was filtered from these zones using an in~situ pump. Lipid biomarkers were extracted from the filters to establish water column profiles of individual hydrocarbons, alcohols, phospholipid fatty acids, and bacteriohopanepolyols (BHPs). As a reference, a cyanobacterial bloom sampled in summer 2012 in the central Baltic Sea Gotland Deep was analyzed for BHPs. The biomarker data from the surface layer of the oxic zone showed major inputs from different cyanobacteria and eukaryotes such as dinoflagellates and ciliates, while the underlying cold winter water layer was characterized by a low diversity and abundance of organisms, with copepods as a major group. The suboxic zone supported bacterivorous ciliates, type I aerobic methanotrophic bacteria, sulfate reducing bacteria, and, most likely, methanogenic archaea. In the anoxic zone, sulfate reducers and archaea were the dominating microorganisms as indicated by the presence of distinctive branched fatty acids, archaeol and PMI derivatives, respectively. Our study of in situ biomarkers in the Landsort Deep thus provided an integrated insight into the distribution of relevant players and the related biogeochemical processes in stratified water columns of marginal seas.

In situ determination of iron(II) in the anoxic zone of the central Baltic Sea using ferene as spectrophotometric reagent

2012 ◽  
Vol 130-131 ◽  
pp. 21-27 ◽  
Author(s):  
David Meyer ◽  
Ralf D. Prien ◽  
Olaf Dellwig ◽  
Douglas P. Connelly ◽  
Detlef E. Schulz-Bull
Keyword(s):  
Baltic Sea ◽  
Anoxic Zone

Tracking the spatiotemporal variability of the oxic–anoxic interface in the Baltic Sea with broadband acoustics

2020 ◽  
Author(s):  
Elizabeth Weidner ◽  
Christian Stranne ◽  
Jonas Hentati Sundberg ◽  
Thomas C Weber ◽  
Larry Mayer ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Baltic Sea ◽  
Water Column ◽  
Acoustic Scattering ◽  
Spatiotemporal Variability ◽  
Coastal Zones ◽  
Anoxic Zone ◽  
The Baltic Sea ◽  
Impedance Contrast ◽  
The Baltic

Abstract Anoxic zones, regions of the water column completely devoid of dissolved oxygen, occur in open oceans and coastal zones worldwide. The Baltic Sea is characterized by strong salinity-driven stratification, maintained by occasional water inflows from the Danish Straights and freshwater input from rivers. Between inflow events, the stratification interface between surface and deep waters hinders mixing and ventilation of deep water; consequently, the bottom waters of large regions of the Baltic are anoxic. The onset of the anoxic zone is closely coincident with the depth of the halocline and, as a result, the interface between oxic and anoxic waters corresponds to a strong impedance contrast. Here, we track acoustic scattering from the impedance contrast utilizing a broadband split-beam echosounder in the Western Gotland Basin and link it to a dissolved oxygen level of 2 ml/l using ground truth stations. The broadband acoustic dataset provides the means to remotely observe the spatiotemporal variations in the oxic–anoxic interface, map out the extent of the anoxic zone with high resolution, and identify several mechanisms influencing the vertical distribution of oxygen in the water column. The method described here can be used to study other systems with applications in ongoing oceanographic monitoring programs.

scholarly journals The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study

2017 ◽  
Vol 14 (2) ◽  
pp. 285-300 ◽  
Author(s):  
Stefano Bonaglia ◽  
Astrid Hylén ◽  
Jayne E. Rattray ◽  
Mikhail Y. Kononets ◽  
Nils Ekeroth ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Nitrate Reduction ◽  
Organic N ◽  
Fixed Nitrogen ◽  
Coastal Station ◽  
Solute Fluxes ◽  
The Baltic ◽  
The Impact

Abstract. Over the last decades, the impact of human activities on the global nitrogen (N) cycle has drastically increased. Consequently, benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while in oligotrophic systems its understanding is still scarce. Here we report on benthic solute fluxes and on rates of denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located in the northern part of the Baltic Sea. Rates of N burial were also inferred to investigate the fate of fixed N in these sediments. Most of the total dissolved fixed nitrogen (TDN) diffusing to the water column was composed of organic N. Average rates of dinitrogen (N2) production by denitrification and anammox (range: 53–360 µmol N m−2 day−1) were comparable to those from Arctic and subarctic sediments worldwide (range: 34–344 µmol N m−2 day−1). Anammox accounted for 18–26 % of the total N2 production. Absence of free hydrogen sulfide and low concentrations of dissolved iron in sediment pore water suggested that denitrification and DNRA were driven by organic matter oxidation rather than chemolithotrophy. DNRA was as important as denitrification at a shallow, coastal station situated in the northern Bothnian Bay. At this pristine and fully oxygenated site, ammonium regeneration through DNRA contributed more than one-third to the TDN efflux and accounted, on average, for 45 % of total nitrate reduction. At the offshore stations, the proportion of DNRA in relation to denitrification was lower (0–16 % of total nitrate reduction). Median value and range of benthic DNRA rates from the GOB were comparable to those from the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loading. However, the mechanisms behind the variability in DNRA rates between our sites were not resolved. The GOB sediments were a major source (237 kt yr−1, which corresponds to 184 % of the external N load) of fixed N to the water column through recycling mechanisms. To our knowledge, our study is the first to document the simultaneous contribution of denitrification, DNRA, anammox, and TDN recycling combined with in situ measurements.

scholarly journals Dissolved iron (II) in the Baltic Sea surface water and implications for cyanobacterial bloom development

2009 ◽  
Vol 6 (11) ◽  
pp. 2397-2420 ◽  
Author(s):  
E. Breitbarth ◽  
J. Gelting ◽  
J. Walve ◽  
L. J. Hoffmann ◽  
D. R. Turner ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Cyanobacterial Bloom ◽  
Euphotic Zone ◽  
Strong Wind ◽  
The Baltic Sea ◽  
Oxic Zone ◽  
Wind Events ◽  
Predicted Values ◽  
The Baltic ◽  
Summer Time

Abstract. Iron chemistry measurements were conducted during summer 2007 at two distinct locations in the Baltic Sea (Gotland Deep and Landsort Deep) to evaluate the role of iron for cyanobacterial bloom development in these estuarine waters. Depth profiles of Fe(II) were measured by chemiluminescent flow injection analysis (CL-FIA). Up to 0.9 nmol Fe(II) L−1 were detected in light penetrated surface waters, which constitutes up to 20% to the dissolved Fe pool. This bioavailable iron source is a major contributor to the Fe requirements of Baltic Sea phytoplankton and apparently plays a major role for cyanobacterial bloom development during our study. Measured Fe(II) half life times in oxygenated water exceed predicted values and indicate organic Fe(II) complexation. Potential sources for Fe(II) ligands, including rainwater, are discussed. Fe(II) concentrations of up to 1.44 nmol L−1 were detected at water depths below the euphotic zone, but above the oxic anoxic interface. Mixed layer depths after strong wind events are not deep enough in summer time to penetrate the oxic-anoxic boundary layer. However, Fe(II) from anoxic bottom water may enter the sub-oxic zone via diapycnal mixing and diffusion.

scholarly journals Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)

2012 ◽  
Vol 9 (12) ◽  
pp. 4969-4977 ◽  
Author(s):  
O. Schmale ◽  
M. Blumenberg ◽  
K. Kießlich ◽  
G. Jakobs ◽  
C. Berndmeyer ◽  
...  
Keyword(s):  
Surface Water ◽  
Baltic Sea ◽  
Water Column ◽  
Methane Oxidation ◽  
Stable Carbon Isotope ◽  
Carbon Isotope Ratio ◽  
Depth Interval ◽  
Type I ◽  
Gotland Deep ◽  
Redox Zone

Abstract. Water column samples taken in summer 2008 from the stratified Gotland Deep (central Baltic Sea) showed a strong gradient in dissolved methane concentrations from high values in the saline deep water (max. 504 nM) to low concentrations in the less dense, brackish surface water (about 4 nM). The steep methane-gradient (between 115 and 135 m water depth) within the redox-zone, which separates the anoxic deep part from the oxygenated surface water (oxygen concentration 0–0.8 mL L−1), implies a methane consumption rate of 0.28 nM d−1. The process of microbial methane oxidation within this zone was evident by a shift of the stable carbon isotope ratio of methane between the bottom water (δ13C CH4 = −82.4‰ and the redox-zone (δ13C CH4 = −38.7‰. Water column samples between 80 and 119 m were studied to identify the microorganisms responsible for the methane turnover in that depth interval. Notably, methane monooxygenase gene expression analyses for water depths covering the whole redox-zone demonstrated that accordant methanotrophic activity was probably due to only one phylotype of the aerobic type I methanotrophic bacteria. An imprint of these organisms on the particular organic matter was revealed by distinctive lipid biomarkers showing bacteriohopanepolyols and lipid fatty acids characteristic for aerobic type I methanotrophs (e.g., 35-aminobacteriohopane-30,31,32,33,34-pentol), corroborating their role in aerobic methane oxidation in the redox-zone of the central Baltic Sea.

scholarly journals Oil Pollution Of The Southeastern Baltic Sea By Satellite Remote Sensing Data And In-Situ Measurements

2015 ◽  
Vol 16 (4) ◽  
pp. 296-304 ◽  
Author(s):  
Elena V. Bulycheva ◽  
Aleksander V. Krek ◽  
Andrey G. Kostianoy ◽  
Aleksander V. Semenov ◽  
Aleksandar Joksimovich
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Oil Pollution ◽  
Temporal Distribution ◽  
Remote Sensing Data ◽  
In Situ Measurements ◽  
Oil Products ◽  
Satellite Monitoring ◽  
First Time

Abstract Results of operational satellite monitoring of oil pollution of the sea surface together with in-situ measurements of the oil products concentration in the water column for the first time allowed to establish relation between the surface pollution originated from ships, and the general characteristics of spatial and temporal distribution of oil products in the water column in the Southeastern Baltic Sea. Areas with heightened concentrations of oil products in the surface and bottom layers were determined for the study area. The main directions of the contamination propagation are agreed with the main direction of annual mean transport of substances in the Gdansk Basin.

scholarly journals The fate of fixed nitrogen in oligotrophic marine sediments: an in situ study

2016 ◽  
Author(s):  
Stefano Bonaglia ◽  
Astrid Hylén ◽  
Jayne E. Rattray ◽  
Mikhail Y. Kononets ◽  
Nils Ekeroth ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Nitrate Reduction ◽  
Pore Waters ◽  
Coastal Station ◽  
Total Dissolved Nitrogen ◽  
Solute Fluxes ◽  
The Baltic ◽  
Bothnian Bay

Abstract. Given the increasing impacts of human activities on global nitrogen (N) cycle, investigations on N transformation processes in the marine environment have drastically increased in the last years. Benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while its understanding in oligotrophic systems is still scarce. Here we report on rates of denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located in the northern part of the Baltic Sea. Burial and benthic solute fluxes were also experimentally determined to investigate the fate of fixed N in these sediments. Average rates of N2 production by denitrification and anammox (range 53–360 µmol N m−2 d−1) were comparable to those from Arctic and subarctic sediments worldwide (range 34–344 µmol N m−2 d−1). Anammox accounted for 18–26 % of the total N2 production. Absence of free hydrogen sulfide and low concentrations of dissolved iron in sediment pore waters suggested that denitrification and DNRA were driven by organic matter oxidation rather than chemolithotrophy. DNRA was as important as denitrification at a shallow, coastal station situated in the northern Bothnian Bay. At this pristine and fully oxygenated site, ammonium regeneration through DNRA contributed more than one third to the total dissolved nitrogen (TDN) diffusing from the sediment to the water column, and accounted, on average, for 45 % of total nitrate reduction. At the offshore stations, the proportion of DNRA in relation to denitrification was lower (0–16 % of total nitrate reduction). Median value and range of benthic DNRA rates from the GOB were comparable to those from the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loads. However, the mechanisms behind the variability in DNRA rates between our sites were not resolved. The GOB sediments were a major source (237 kt y−1, which corresponds to 184 % of the external N load) of fixed N to the water column through recycling mechanisms. To our knowledge, our study is the first to document the simultaneous contribution of denitrification, DNRA, anammox and TDN recycling combined with in situ measurements.

scholarly journals Microbial methane oxidation at the redoxcline of the Gotland Deep (Central Baltic Sea)

2012 ◽  
Vol 9 (7) ◽  
pp. 8783-8805 ◽  
Author(s):  
O. Schmale ◽  
M. Blumenberg ◽  
K. Kießlich ◽  
G. Jakobs ◽  
C. Berndmeyer ◽  
...  
Keyword(s):  
Surface Water ◽  
Baltic Sea ◽  
Water Column ◽  
Methane Oxidation ◽  
Water Depth ◽  
Stable Carbon Isotope ◽  
Depth Interval ◽  
Type I ◽  
Gotland Deep ◽  
Key Species

Abstract. Methane concentrations in the stratified water column of the Gotland Deep (Central Baltic Sea) show a strong gradient from high values in the saline deep water (max. 504nM) to low concentrations in the less dense, brackish surface water (about 4 nM). The steepest gradient is present within the redoxcline (between 115 and 135 m water depth) that separates the anoxic deep part from the oxygenated surface water, implying a methane consumption rate of 0.28 nM d−1. The process of microbial methane oxidation within the redoxcline is mirrored by a shift of the stable carbon isotope ratio of methane between the bottom water (δ13C CH4 = −82.4‰) and the suboxic depth interval (δ13C CH4 = −38.7‰). A water column sample from 100 m water depth was studied to identify the microorganisms responsible for the methane turnover at the redoxcline. Notably, methane monoxygenase gene expression analyses for the specific water depth demonstrated that accordant methanotrophic activity was due to only one microbial phylotype. An imprint of these organisms on the particular organic matter was revealed by distinctive lipid biomarkers showing bacteriohopanepolyols and lipid fatty acids characteristic for aerobic type I methanotrophic bacteria (e.g. 35-aminobacteriohopane-30,31,32,33,34-pentol). In conjunction with earlier findings, our results support the idea that biogeochemical cycles in Central Baltic Sea redoxclines are mainly driven by only a few microbial key species.

scholarly journals Methanotrophy within the water column of a large meromictic tropical lake (Lake Kivu, East Africa)

2015 ◽  
Vol 12 (7) ◽  
pp. 2077-2088 ◽  
Author(s):  
C. Morana ◽  
A. V. Borges ◽  
F. A. E. Roland ◽  
F. Darchambeau ◽  
J.-P. Descy ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Water Column ◽  
Stable Carbon Isotope ◽  
Isotope Analysis ◽  
Bacterial Growth Efficiency ◽  
Substantial Contribution ◽  
Type I ◽  
Ch4 Oxidation ◽  
Lake Kivu ◽  
Upward Flux

Abstract. The permanently stratified Lake Kivu is one of the largest freshwater reservoirs of dissolved methane (CH4) on Earth. Yet CH4 emissions from its surface to the atmosphere have been estimated to be 2 orders of magnitude lower than the CH4 upward flux to the mixed layer, suggesting that microbial CH4 oxidation is an important process within the water column. A combination of natural abundance stable carbon isotope analysis (δ13C) of several carbon pools and 13CH4-labelling experiments was carried out during the rainy and dry season to quantify (i) the contribution of CH4-derived carbon to the biomass, (ii) methanotrophic bacterial production (MBP), and (iii) methanotrophic bacterial growth efficiency (MBGE), defined as the ratio between MBP and gross CH4 oxidation. We also investigated the distribution and the δ13C of specific phospholipid fatty acids (PLFAs), used as biomarkers for aerobic methanotrophs. Maximal MBP rates were measured in the oxycline, suggesting that CH4 oxidation was mainly driven by oxic processes. Moreover, our data revealed that methanotrophic organisms in the water column oxidized most of the upward flux of CH4, and that a significant amount of CH4-derived carbon was incorporated into the microbial biomass in the oxycline. The MBGE was variable (2–50%) and negatively related to CH4 : O2 molar ratios. Thus, a comparatively smaller fraction of CH4-derived carbon was incorporated into the cellular biomass in deeper waters, at the bottom of the oxycline where oxygen was scarce. The aerobic methanotrophic community was clearly dominated by type I methanotrophs and no evidence was found for an active involvement of type II methanotrophs in CH4 oxidation in Lake Kivu, based on fatty acids analyses. Vertically integrated over the water column, the MBP was equivalent to 16–60% of the average phytoplankton particulate primary production. This relatively high magnitude of MBP, and the substantial contribution of CH4-derived carbon to the overall biomass in the oxycline, suggest that methanotrophic bacteria could potentially sustain a significant fraction of the pelagic food web in the deep, meromictic Lake Kivu.

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