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.

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.

scholarly journals Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

2010 ◽  
Vol 7 (8) ◽  
pp. 2489-2508 ◽  
Author(s):  
J. Gelting ◽  
E. Breitbarth ◽  
B. Stolpe ◽  
M. Hassellöv ◽  
J. Ingri
Keyword(s):  
Baltic Sea ◽  
Isotope Composition ◽  
Salinity Gradient ◽  
Euphotic Zone ◽  
Early Spring ◽  
Strong Positive Correlation ◽  
The Baltic Sea ◽  
Gotland Deep ◽  
The Baltic ◽  
Bothnian Sea

Abstract. To indentify sources and transport mechanisms of iron in a coastal marine environment, we conducted measurements of the physiochemical speciation of Fe in the euphotic zone at three different locations in the Baltic Sea. In addition to sampling across a salinity gradient, we conducted this study over the spring and summer season. Moving from the riverine input characterized low salinity Bothnian Sea, via the Landsort Deep near Stockholm, towards the Gotland Deep in the Baltic Proper, total Fe concentrations averaged 114, 44, and 15 nM, respectively. At all three locations, a decrease in total Fe of 80–90% from early spring to summer was observed. Particulate Fe (PFe) was the dominating phase at all stations and accounted for 75–85% of the total Fe pool on average. The Fe isotope composition (δ 56Fe) of the PFe showed constant positive values in the Bothnian Sea surface waters (+0.08 to +0.20‰). Enrichment of heavy Fe in the Bothnian Sea PFe is possibly associated to input of aggregated land derived Fe-oxyhydroxides and oxidation of dissolved Fe(II). At the Landsort Deep the isotopic fractionation of PFe changed between −0.08‰ to +0.28‰ over the sampling period. The negative values in early spring indicate transport of PFe from the oxic-anoxic boundary at ∼80 m depth. The average colloidal iron fraction (CFe) showed decreasing concentrations along the salinity gradient; Bothnian Sea 15 nM; Landsort Deep 1 nM, and Gotland Deep 0.5 nM. Field Flow Fractionation data indicate that the main colloidal carrier phase for Fe in the Baltic Sea is a carbon-rich fulvic acid associated compound, likely of riverine origin. A strong positive correlation between PFe and chl-a indicates that cycling of suspended Fe is at least partially controlled by primary production. However, this relationship may not be dominated by active uptake of Fe into phytoplankton, but instead may reflect scavenging and removal of PFe during phytoplankton sedimentation.

scholarly journals EU macro-regional strategies for the Baltic Sea Region after 2020. A nutshell of beauty and possibilities

Europa XXI ◽  
2019 ◽  
Vol 38 ◽  
Author(s):  
Jacek Zaucha ◽  
Kai Böhme ◽  
Dorota Pyć ◽  
Lilia Neumann ◽  
Aziewicz Dominik
Keyword(s):  
European Union ◽  
Baltic Sea ◽  
Economies Of Scale ◽  
The European Union ◽  
The Baltic Sea ◽  
Positive Effects ◽  
Regional Strategies ◽  
Soft Governance ◽  
Baltic Sea Region ◽  
The Baltic

The European Union Strategy for the Baltic Sea Region, that celebrates this year in Gdańsk its tenth anniversary, has been considered by many scholars and the decision makers as the model example of the soft governance that has gained in importance in the enlarged European Union (EU). The paper analyses the achievements and shortcomings of the Strategy from economic perspective with focus on externalities, public goods (also club goods, common-pool resources), economies of scale and scope and transaction costs. Two cases: Single Market for services and innovation spillovers are discussed more in depth. The analysis of these challenges and opportunities as well as the performance of the Strategy in the past and comparative analysis of its various evaluations allow authors to formulate several assumptions that should save the Strategy for the future. Their essence is related to mainstreaming of the Strategy into the EU and national policies (ensuring its stronger policy impact), strengthening strategic, visionary approach of the Strategy (e.g. facilitating large Baltic projects), better alignment with the business sector activities (understanding and addressing this sector expectations towards macro-regional co-operation) and acknowledgement of macro-regional solidarity as a foundation of the common efforts. Without all these, the Strategy might follow the case of the Baltic Development Forum that ceased to exist despite its evident positive effects for the entire region. Soft governance is difficult but promising as an alternative to the overgrowing sentiments towards centralisation. Thus, to avoid the impression of the “Titanic ball” Gdańsk celebrations should provide a new start instead of the business as usual and manifestation of shallow self-satisfaction.

scholarly journals Ventilation of the Northern Baltic Sea

2019 ◽  
Author(s):  
Thomas Neumann ◽  
Herbert Siegel ◽  
Matthias Moros ◽  
Monika Gerth ◽  
Madline Kniebusch ◽  
...  
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Deep Water ◽  
Bottom Water ◽  
Ice Core ◽  
Winter Season ◽  
The Baltic Sea ◽  
The Baltic ◽  
Bothnian Bay ◽  
Bothnian Sea

Abstract. The Baltic Sea is a semi-enclosed, brackish water sea in northern Europe. The deep basins of the central Baltic Sea regularly show hypoxic conditions. In contrast, the northern parts of the Baltic Sea, the Bothnian Sea and Bay, are well oxygenated. Lateral inflows or a ventilation due to convection are possible mechanisms for high oxygen concentrations in the deep water of the northern Baltic Sea. Owing to the high latitudes of the northern Baltic, this region is regularly covered by sea ice during the winter season. In March 2017, the RV Maria S. Merian was for two days in the Bothnian Bay collecting ice core samples, brine water, and CTD profiles. The bulk sea ice salinity was on average 0.6 g/kg and in brine samples, a salinity of 11.5 g/kg and 17.8 g/kg have been measured. At one station, the CTD profiles indicated a recent ventilation event of the deep water. A water mass analysis showed that the ventilation is most probably due to mixing of Bothnian Sea and Bothnian Bay surface water which results in sufficient dense water able to replace older bottom water. However, the high salinity of brine provides the potential for forming dense bottom water masses as well.

scholarly journals Impacts of changing society and climate on nutrient loading to the Baltic Sea

2020 ◽  
Vol 731 ◽  
pp. 138935 ◽  
Author(s):  
Sampo Pihlainen ◽  
Marianne Zandersen ◽  
Kari Hyytiäinen ◽  
Hans Estrup Andersen ◽  
Alena Bartosova ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Nutrient Loading ◽  
The Baltic Sea ◽  
The Baltic ◽  
Changing Society

Effects of climate change and agricultural adaptation on nutrient loading from Finnish catchments to the Baltic Sea

2015 ◽  
Vol 529 ◽  
pp. 168-181 ◽  
Author(s):  
Inese Huttunen ◽  
Heikki Lehtonen ◽  
Markus Huttunen ◽  
Vanamo Piirainen ◽  
Marie Korppoo ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Nutrient Loading ◽  
The Baltic Sea ◽  
Agricultural Adaptation ◽  
The Baltic

scholarly journals Ventilation of the northern Baltic Sea

Ocean Science ◽  
2020 ◽  
Vol 16 (4) ◽  
pp. 767-780 ◽  
Author(s):  
Thomas Neumann ◽  
Herbert Siegel ◽  
Matthias Moros ◽  
Monika Gerth ◽  
Madline Kniebusch ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Bottom Water ◽  
Model Simulation ◽  
Ice Core ◽  
The Baltic Sea ◽  
Hypoxic Conditions ◽  
The Baltic ◽  
Bothnian Bay ◽  
Temperature Depth ◽  
Bothnian Sea

Abstract. The Baltic Sea is a semi-enclosed, brackish water sea in northern Europe. The deep basins of the central Baltic Sea regularly show hypoxic conditions. In contrast, the northern parts of the Baltic Sea, the Bothnian Sea and Bothnian Bay, are well oxygenated. Lateral inflows or a ventilation due to convection are possible mechanisms for high oxygen concentrations in the deep water of the northern Baltic Sea. In March 2017, conductivity–temperature–depth (CTD) profiles and bottle samples, ice core samples, and brine were collected in the Bothnian Bay. In addition to hydrographic standard parameters, light absorption has been measured in all samples. A complementary numerical model simulation provides quantitative estimates of the spread of newly formed bottom water. The model uses passive and age tracers to identify and trace different water masses. Observations indicate a recent ventilation of the deep bottom water at one of the observed stations. The analysis of observations and model simulations shows that the Bothnian Bay is ventilated by dense water formed due to mixing of Bothnian Sea and Bothnian Bay surface water initializing lateral inflows. The observations show the beginning of the inflow and the model simulation demonstrates the further northward spreading of bottom water. These events occur during wintertime when the water temperature is low. Brine rejected during ice formation barely contributes to dense bottom water.

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