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 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.

scholarly journals Nutrient transports in the Baltic Sea – results from a 30-year physical–biogeochemical reanalysis

2017 ◽  
Vol 14 (8) ◽  
pp. 2113-2131 ◽  
Author(s):  
Ye Liu ◽  
H. E. Markus Meier ◽  
Kari Eilola
Keyword(s):  
Baltic Sea ◽  
Cross Sections ◽  
Ocean Model ◽  
Optimal Interpolation ◽  
Nutrient Concentrations ◽  
Biogeochemical Model ◽  
The Baltic Sea ◽  
Gulf Of Riga ◽  
Baltic Proper ◽  
The Baltic

Abstract. Long-term oxygen and nutrient transports in the Baltic Sea are reconstructed using the Swedish Coastal and Ocean Biogeochemical model (SCOBI) coupled to the Rossby Centre Ocean model (RCO). Two simulations with and without data assimilation covering the period 1970–1999 are carried out. Here, the weakly coupled scheme with the Ensemble Optimal Interpolation (EnOI) method is adopted to assimilate observed profiles in the reanalysis system. The reanalysis shows considerable improvement in the simulation of both oxygen and nutrient concentrations relative to the free run. Further, the results suggest that the assimilation of biogeochemical observations has a significant effect on the simulation of the oxygen-dependent dynamics of biogeochemical cycles. From the reanalysis, nutrient transports between sub-basins, between the coastal zone and the open sea, and across latitudinal and longitudinal cross sections are calculated. Further, the spatial distributions of regions with nutrient import or export are examined. Our results emphasize the important role of the Baltic proper for the entire Baltic Sea, with large net transport (export minus import) of nutrients from the Baltic proper into the surrounding sub-basins (except the net phosphorus import from the Gulf of Riga and the net nitrogen import from the Gulf of Riga and Danish Straits). In agreement with previous studies, we found that the Bothnian Sea imports large amounts of phosphorus from the Baltic proper that are retained in this sub-basin. For the calculation of sub-basin budgets, the location of the lateral borders of the sub-basins is crucial, because net transports may change sign with the location of the border. Although the overall transport patterns resemble the results of previous studies, our calculated estimates differ in detail considerably.

scholarly journals Nutrient cycling in the Baltic Sea – results from a 30-year physical-biogeochemical reanalysis

2016 ◽  
Author(s):  
Ye Liu ◽  
H. E. Markus Meier ◽  
Kari Eilola
Keyword(s):  
Baltic Sea ◽  
Ocean Model ◽  
Optimal Interpolation ◽  
Nutrient Concentrations ◽  
Biogeochemical Model ◽  
Phosphorus Transport ◽  
The Baltic Sea ◽  
Gulf Of Riga ◽  
Baltic Proper ◽  
The Baltic

Abstract. The long-term oxygen and nutrient cycles in the Baltic Sea are reconstructed using the Swedish Coastal and Ocean Biogeochemical model (SCOBI) coupled to the Rossby Centre Ocean model (RCO). Two simulations covering the period 1970–1999 are carried out with and without data assimilation, respectively. Here, the "weakly coupled" scheme with the Ensemble Optimal Interpolation (EnOI) method is adopted to assimilate the observed profiles in the reanalysis system. The simulation results show considerable improvements in both oxygen and nutrient concentrations in the reanalysis relative to the free run. Further, the results suggest that the assimilation of biogeochemical observations has a significant effect on the simulation of the oxygen dependent dynamics of biogeochemical cycles. From the reanalysis, nutrient transports between subbasins, between the coastal zone and the open sea, and across latitudinal and longitudinal cross sections, are calculated. Further, bottom areas of nutrient import or export are examined. Our results emphasize the important role of the Baltic proper for the entire Baltic Sea, with large net exports of nutrients into the surrounding subbasins (except the phosphorus transport into the Gulf of Riga and the nitrogen transports into the Gulf of Riga and Danish Straits). In agreement with previous studies, we found that the Bothnian Sea imports large amounts of phosphorus from the Baltic proper that are buried in this subbasin. For the calculation of subbasin budgets, it is crucial where the lateral borders of the subbasins are located, because net transports may change sign with the location of the border. Although the overall transport patterns resemble the results of previous studies, our calculated estimates differ in detail considerably.

scholarly journals Supplementary material to "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 ◽  
The Baltic Sea ◽  
Supplementary Material ◽  
The Baltic

scholarly journals Assessment of a physical-biogeochemical coupled model system for operational service in the Baltic Sea

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 683-701 ◽  
Author(s):  
Z. Wan ◽  
J. She ◽  
M. Maar ◽  
L. Jonasson ◽  
J. Baasch-Larsen
Keyword(s):  
Baltic Sea ◽  
Inorganic Nitrogen ◽  
Biogeochemical Model ◽  
Observation Data ◽  
Model Assessment ◽  
Model Errors ◽  
The Baltic Sea ◽  
Statistical Measures ◽  
The Baltic ◽  
Operational Service

Abstract. Thanks to the abundant observation data, we are able to deploy the traditional point-to-point comparison and statistical measures in combination with a comprehensive model validation scheme to assess the skills of the biogeochemical model ERGOM in providing an operational service for the Baltic Sea. The model assessment concludes that the operational products can resolve the main observed seasonal features for phytoplankton biomass, dissolved inorganic nitrogen, dissolved inorganic phosphorus and dissolved oxygen in euphotic layers as well as their vertical profiles. This assessment reflects that the model errors of the operational system at the current stage are mainly caused by insufficient light penetration, excessive organic particle export downward, insufficient regional adaptation and some from improper initialization. This study highlights the importance of applying multiple schemes in order to assess model skills rigidly and identify main causes for major model errors.

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 Life cycle bioenergetics of the gray seal (Halichoerus grypus) in the Baltic Sea: Population response to environmental stress

2020 ◽  
Vol 145 ◽  
pp. 106145 ◽  
Author(s):  
Willian T.A.F. Silva ◽  
Karin C. Harding ◽  
Gonçalo M. Marques ◽  
Britt Marie Bäcklin ◽  
Christian Sonne ◽  
...  
Keyword(s):  
Life Cycle ◽  
Environmental Stress ◽  
Baltic Sea ◽  
Halichoerus Grypus ◽  
The Baltic Sea ◽  
Population Response ◽  
Gray Seal ◽  
The Baltic

scholarly journals Sensitivity of oxygen dynamics in the water column of the Baltic Sea to external forcing

Ocean Science ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 461-474 ◽  
Author(s):  
S. Miladinova ◽  
A. Stips
Keyword(s):  
Baltic Sea ◽  
Transport Model ◽  
Meteorological Data ◽  
Biogeochemical Model ◽  
Physical Factors ◽  
Observation Data ◽  
Intermediate Water ◽  
The Baltic Sea ◽  
The Baltic ◽  
Oxygen Dynamics

Abstract. A 1-D biogeochemical/physical model of marine systems has been applied to study the oxygen cycle in four stations of different sub-basins of the Baltic Sea, namely, in the Gotland Deep, Bornholm, Arkona and Fladen. The model consists of the biogeochemical model of Neumann et al. (2002) coupled with the 1-D General Ocean Turbulence Model (GOTM). The model has been forced with meteorological data from the ECMWF reanalysis project for the period 1998–2003, producing a six year hindcast which is validated with datasets from the Baltic Environmental Database (BED) for the same period. The vertical profiles of temperature and salinity are relaxed towards both profiles provided by 3-D simulations of General Estuarine Transport Model (GETM) and observed profiles from BED. Modifications in the parameterisation of the air-sea oxygen fluxes have led to a significant improvement of the model results in the surface and intermediate water layers. The largest mismatch with observations is found in simulating the oxygen dynamics in the Baltic Sea bottom waters. The model results demonstrate the good capability of the model to predict the time-evolution of the physical and biogeochemical variables at all different stations. Comparative analysis of the modelled oxygen concentrations with respect to observation data is performed to distinguish the relative importance of several factors on the seasonal, interannual and long-term variations of oxygen. It is found that natural physical factors, like the magnitude of the vertical turbulent mixing, wind speed and the variation of temperature and salinity fields are the major factors controlling the oxygen dynamics in the Baltic Sea. The influence of limiting nutrients is less pronounced, at least under the nutrient flux parameterisation assumed in the model.

The first large-scale assessment of three-spined stickleback (Gasterosteus aculeatus) biomass and spatial distribution in the Baltic Sea

2019 ◽  
Vol 76 (6) ◽  
pp. 1653-1665 ◽  
Author(s):  
Jens Olsson ◽  
Eglė Jakubavičiūtė ◽  
Olavi Kaljuste ◽  
Niklas Larsson ◽  
Ulf Bergström ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Baltic Sea ◽  
Gasterosteus Aculeatus ◽  
Population Characteristics ◽  
Alternative Methods ◽  
The Baltic Sea ◽  
Baltic Proper ◽  
The Baltic ◽  
The Impact ◽  
Bothnian Sea

Abstract Declines in predatory fish in combination with the impact of climate change and eutrophication have caused planktivores, including three-spined stickleback (Gasterosteus aculeatus), to increase dramatically in parts of the Baltic Sea. Resulting impacts of stickleback on coastal and offshore foodwebs have been observed, highlighting the need for increased knowledge on its population characteristics. In this article, we quantify abundance, biomass, size structure, and spatial distribution of stickleback using data from the Swedish and Finnish parts of the Baltic International Acoustic Survey (BIAS) during 2001–2014. Two alternative methods for biomass estimation suggest an increase in biomass of stickleback in the Baltic Proper, stable or increasing mean size over time, and larger individuals toward the north. The highest abundance was found in the central parts of the Baltic Proper and Bothnian Sea. The proportion of stickleback biomass in the total planktivore biomass increased from 4 to 10% in the Baltic Proper and averaged 6% of the total planktivore biomass in the Bothnian Sea. In some years, however, stickleback biomass has ranged from half to almost twice that of sprat (Sprattus sprattus) in both basins. Given the recent population expansion of stickleback and its potential role in the ecosystem, we recommend that stickleback should be considered in future monitoring programmes and in fisheries and environmental management of the Baltic Sea.

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