scholarly journals Evidence of nitrogen fixation by non-heterocystous cyanobacteria in the Baltic Sea and re-calculation of a budget of nitrogen fixation

2001 ◽  
Vol 214 ◽  
pp. 1-14 ◽  
Author(s):  
N Wasmund ◽  
M Voss ◽  
K Lochte
Keyword(s):  
Nitrogen Fixation ◽  
Baltic Sea ◽  
The Baltic Sea ◽  
Heterocystous Cyanobacteria ◽  
The Baltic

scholarly journals Nitrogen fixation estimates for the Baltic Sea indicate high rates for the previously overlooked Bothnian Sea

AMBIO ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 203-214 ◽  
Author(s):  
Malin Olofsson ◽  
Isabell Klawonn ◽  
Bengt Karlson
Keyword(s):  
Nitrogen Fixation ◽  
Baltic Sea ◽  
Nutrient Loading ◽  
External Input ◽  
Nitrogen Loading ◽  
External Loading ◽  
The Baltic Sea ◽  
Positive Effects ◽  
The Baltic ◽  
Bothnian Sea

AbstractDense blooms of diazotrophic filamentous cyanobacteria are formed every summer in the Baltic Sea. We estimated their contribution to nitrogen fixation by combining two decades of cyanobacterial biovolume monitoring data with recently measured genera-specific nitrogen fixation rates. In the Bothnian Sea, estimated nitrogen fixation rates were 80 kt N year−1, which has doubled during recent decades and now exceeds external loading from rivers and atmospheric deposition of 69 kt year−1. The estimated contribution to the Baltic Proper was 399 kt N year−1, which agrees well with previous estimates using other approaches and is greater than the external input of 374 kt N year−1. Our approach can potentially be applied to continuously estimate nitrogen loads via nitrogen fixation. Those estimates are crucial for ecosystem adaptive management since internal nitrogen loading may counteract the positive effects of decreased external nutrient loading.

scholarly journals Salinity as a key control on the diazotrophic community composition in the Baltic Sea

2021 ◽  
Author(s):  
Christian Furbo Reeder ◽  
Ina Stoltenberg ◽  
Jamileh Javidpour ◽  
Carolin Regina Löscher
Keyword(s):  
Baltic Sea ◽  
Community Composition ◽  
N2 Fixation ◽  
Statistical Testing ◽  
Functional Marker ◽  
The Baltic Sea ◽  
Heterocystous Cyanobacteria ◽  
The Baltic ◽  
The Impact ◽  
Diazotrophic Community

Abstract. Over the next decade, the Baltic Sea is predicted to undergo severe changes including a decrease in salinity due to altering precipitation. This will likely impact the distribution and community composition of Baltic Sea N2 fixing microbes, of which especially heterocystous cyanobacteria are adapted to low salinities and may expand to waters with currently higher salinity, including the Danish Strait and Kattegat, while other high-salinity adapted N2 fixers might decrease in abundance. In order to explore the impact of salinity on the distribution and activity of different diazotrophic clades, we followed the natural salinity gradient from the Eastern Gotland and Bornholm Basins through the Arkona Basin to the Kiel Bight and combined N2 fixation rate measurements with a molecular analysis of the diazotrophic community using the key functional marker gene for N2 fixation nifH, as well as the key functional marker genes anf and vnf, encoding for the two alternative nitrogenases. We detected N2 fixation rates between 0.7 and 6 nmol N L-1 d-1, and the diazotrophic community was dominated by the cyanobacterium Nodularia and the small unicellular, cosmopolitan cyanobacterium UCYN-A. Nodularia was present in abundances between 8.07 x 105 and 1.6 x 107 copies L-1 in waters with salinities of 10 and below, while UCYN-A reached abundances of up to 4.5 x 107 copies L-1 in waters with salinity above 10. Besides those two cyanobacterial diazotrophs, we found several clades of proteobacterial N2 fixers and alternative nitrogenase genes associated with Rhodopseudomonas palustris, a purple non-sulfur bacterium. Based on statistical testing, salinity was identified as the primary parameter describing the diazotrophic distribution, while pH and temperature did not have a similarly significant influence on the diazotrophic distribution. While this statistical analysis will need to be explored in direct experiments, it gives an indication for a future development of diazotrophy in a freshening Baltic Sea with UCYN-A retracting to more saline North Sea waters and heterocystous cyanobacteria expanding as salinity decreases.

scholarly journals Modeling cyanobacteria life cycle dynamics and historical nitrogen fixation in the Baltic Sea

2021 ◽  
Author(s):  
Jenny Hieronymus ◽  
Kari Eilola ◽  
Malin Olofsson ◽  
Inga Hense ◽  
H. E. Markus Meier ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Life Cycle ◽  
Baltic Sea ◽  
Inorganic Phosphorus ◽  
Biogeochemical Model ◽  
Model Combination ◽  
The Baltic Sea ◽  
Nitrogen Loads ◽  
Explicit Consideration ◽  
The Baltic

Abstract. Dense blooms of filamentous diazotrophic cyanobacteria are formed every summer in the Baltic Sea. These autotrophic organisms may bypass nitrogen limitation by performing nitrogen fixation, which also governs surrounding organisms by releasing bioavailable nitrogen. The magnitude of the nitrogen fixation is important to estimate from a management perspective since this might counteract eutrophication reduction measures. Here, a cyanobacteria life cycle model has been implemented for the first time in a high-resolution 3D coupled physical and biogeochemical model of the Baltic Sea spanning the years 1850–2008. The explicit consideration of life cycle dynamics and transitions significantly improves the representation of the cyanobacterial phenological patterns. Compared to earlier 3D-modelling efforts, the rapid increase and decrease of cyanobacteria in the Baltic Sea is well captured by our developed model and is now in concert with observations. The current improvement in timing of cyanobacteria blooms had a large effect on the estimated nitrogen fixation load and is in agreement with in situ measurements. By performing four phosphorus sensitivity runs we demonstrate the importance of both organic and inorganic phosphorus availability for historical cyanobacterial biomass estimates. The used model combination can be used to continuously estimate internal nitrogen loads via nitrogen fixation in Baltic Sea ecosystem management, which is of extra importance in a future ocean with changed conditions for the filamentous cyanobacteria.

A nitrogen fixation estimate for the Baltic Sea based on continuous pCO2 measurements on a cargo ship and total nitrogen data

2009 ◽  
Vol 29 (11-12) ◽  
pp. 1535-1540 ◽  
Author(s):  
Bernd Schneider ◽  
Seppo Kaitala ◽  
Mika Raateoja ◽  
Bernd Sadkowiak
Keyword(s):  
Nitrogen Fixation ◽  
Baltic Sea ◽  
Total Nitrogen ◽  
The Baltic Sea ◽  
The Baltic

scholarly journals Model study on horizontal variability of nutrient N/P ratio in the Baltic Sea and its impacts on primary production, nitrogen fixation and nutrient limitation

2012 ◽  
Vol 9 (1) ◽  
pp. 385-419 ◽  
Author(s):  
Z. Wan ◽  
H. Bi ◽  
J. She ◽  
M. Maar ◽  
L. Jonasson
Keyword(s):  
Nitrogen Fixation ◽  
Primary Production ◽  
Baltic Sea ◽  
Nutrient Limitation ◽  
Inorganic Nitrogen ◽  
Fixed Ratio ◽  
Model Performance ◽  
Nutrient Concentrations ◽  
The Baltic Sea ◽  
The Baltic

Abstract. The analysis of measured nutrient concentrations suggests that the ratio of dissolved inorganic nitrogen (DIN) alteration before and after spring blooms relative to the alteration of dissolved inorganic phosphorus (DIP) remains quite constant over the years (2000~2009). This ratio differs from the Redfield ratio and varies from 6.6 : 1 to 41.5 : 1 across basins within the Baltic Sea. If the found N/P ratios are indicators of phytoplankton stoichiometry, this would affect nutrient cycles in ecosystem models. We therefore tested the effects of using horizontally variable N/P ratio instead of fixed ratio (N/P = 10 : 1 or 16 : 1) on phytoplankton uptake and remineralization in a 3-D physical-biogeochemical coupled model ERGOM. The model results using the variable N/P ratio show systematical improvements in model performance in comparison with the fixed ratios. In addition, variable N/P ratios greatly affected the model estimated primary production, nitrogen fixation and nutrient limitation, which highlights the importance of using an accurate N/P ratio.

scholarly journals Modeling cyanobacteria life cycle dynamics and historical nitrogen fixation in the Baltic Proper

2021 ◽  
Vol 18 (23) ◽  
pp. 6213-6227
Author(s):  
Jenny Hieronymus ◽  
Kari Eilola ◽  
Malin Olofsson ◽  
Inga Hense ◽  
H. E. Markus Meier ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Life Cycle ◽  
Baltic Sea ◽  
Inorganic Phosphorus ◽  
Biogeochemical Model ◽  
Model Combination ◽  
The Baltic Sea ◽  
Explicit Consideration ◽  
Baltic Proper ◽  
The Baltic

Abstract. Dense blooms of filamentous diazotrophic cyanobacteria are formed every summer in the Baltic Sea. These autotrophic organisms may bypass nitrogen limitation by performing nitrogen fixation, which also governs surrounding organisms by increasing bioavailable nitrogen. The magnitude of the nitrogen fixation is important to estimate from a management perspective since this might counteract eutrophication reduction measures. Here, a cyanobacteria life cycle model has been implemented for the first time in a high-resolution 3D coupled physical and biogeochemical model of the Baltic Sea, spanning the years 1850–2008. The explicit consideration of life cycle dynamics and transitions significantly improves the representation of the cyanobacterial phenological patterns compared to earlier 3D modeling efforts. Now, the rapid increase and decrease in cyanobacteria in the Baltic Sea are well captured, and the seasonal timing is in concert with observations. The current improvement also had a large effect on the nitrogen fixation load and is now in agreement with estimates based on in situ measurements. By performing four phosphorus sensitivity runs, we demonstrate the importance of both organic and inorganic phosphorus availability for historical cyanobacterial biomass estimates. The model combination can be used to continuously predict internal nitrogen loads via nitrogen fixation in Baltic Sea ecosystem management, which is of extra importance in a future ocean with changed conditions for the filamentous cyanobacteria.

scholarly journals The Holocene sedimentary record of cyanobacterial glycolipids in the Baltic Sea: an evaluation of their application as tracers of past nitrogen fixation

2017 ◽  
Vol 14 (24) ◽  
pp. 5789-5804 ◽  
Author(s):  
Martina Sollai ◽  
Ellen C. Hopmans ◽  
Nicole J. Bale ◽  
Anchelique Mets ◽  
Lisa Warden ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Cyanobacterial Blooms ◽  
The Baltic Sea ◽  
The Holocene ◽  
Heterocystous Cyanobacteria ◽  
Cyanobacterial Species ◽  
The Baltic ◽  
Abundance And Distribution ◽  
Yoldia Sea ◽  
Ancylus Lake

Abstract. Heterocyst glycolipids (HGs) are lipids exclusively produced by heterocystous dinitrogen-fixing cyanobacteria. The Baltic Sea is an ideal environment to study the distribution of HGs and test their potential as biomarkers because of its recurring summer phytoplankton blooms, dominated by a few heterocystous cyanobacterial species of the genera Nodularia and Aphanizomenon. A multi-core and a gravity core from the Gotland Basin were analyzed to determine the abundance and distribution of a suite of selected HGs at a high resolution to investigate the changes in past cyanobacterial communities during the Holocene. The HG distribution of the sediments deposited during the Modern Warm Period (MoWP) was compared with those of cultivated heterocystous cyanobacteria, including those isolated from Baltic Sea waters, revealing high similarity. However, the abundance of HGs dropped substantially with depth, and this may be caused by either a decrease in the occurrence of the cyanobacterial blooms or diagenesis, resulting in partial destruction of the HGs. The record also shows that the HG distribution has remained stable since the Baltic turned into a brackish semi-enclosed basin ∼ 7200 cal. yr BP. This suggests that the heterocystous cyanobacterial species composition remained relatively stable as well. During the earlier freshwater phase of the Baltic (i.e., the Ancylus Lake and Yoldia Sea phases), the distribution of the HGs varied much more than in the subsequent brackish phase, and the absolute abundance of HGs was much lower than during the brackish phase. This suggests that the cyanobacterial community adjusted to the different environmental conditions in the basin. Our results confirm the potential of HGs as a specific biomarker of heterocystous cyanobacteria in paleo-environmental studies.

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