The daily integral of nitrogen fixation by planktonic cyanobacteria in the Baltic 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.

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Nitrogen fixation by diazotrophic cyanobacteria in the Baltic Sea and transfer of the newly fixed nitrogen to picoplankton organisms

Journal of Marine Systems ◽

10.1016/s0924-7963(00)00016-6 ◽

2000 ◽

Vol 25 (3-4) ◽

pp. 213-219 ◽

Cited By ~ 70

Author(s):

Ute Ohlendieck ◽

Annegret Stuhr ◽

Heike Siegmund

Keyword(s):

Nitrogen Fixation ◽

Baltic Sea ◽

Fixed Nitrogen ◽

The Baltic Sea ◽

Diazotrophic Cyanobacteria ◽

The Baltic

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Eutrophication in the Baltic Sea and shifts in nitrogen fixation analyzed with a 3D ecosystem model

Journal of Marine Systems ◽

10.1016/j.jmarsys.2008.05.003 ◽

2008 ◽

Vol 74 (1-2) ◽

pp. 592-602 ◽

Cited By ~ 71

Author(s):

Thomas Neumann ◽

Gerald Schernewski

Keyword(s):

Nitrogen Fixation ◽

Baltic Sea ◽

Ecosystem Model ◽

The Baltic Sea ◽

The Baltic ◽

And Shifts

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

10.5194/bg-2021-156 ◽

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.

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

Continental Shelf Research ◽

10.1016/j.csr.2009.04.001 ◽

2009 ◽

Vol 29 (11-12) ◽

pp. 1535-1540 ◽

Cited By ~ 32

Author(s):

Bernd Schneider ◽

Seppo Kaitala ◽

Mika Raateoja ◽

Bernd Sadkowiak

Keyword(s):

Nitrogen Fixation ◽

Baltic Sea ◽

Total Nitrogen ◽

The Baltic Sea ◽

The Baltic

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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

Ocean Science Discussions ◽

10.5194/osd-9-385-2012 ◽

2012 ◽

Vol 9 (1) ◽

pp. 385-419 ◽

Cited By ~ 5

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.

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

Biogeosciences ◽

10.5194/bg-18-6213-2021 ◽

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.

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