scholarly journals Seasonal cycle of benthic denitrification and DNRA in the aphotic coastal zone, northern Baltic Sea

2020 ◽  
Vol 637 ◽  
pp. 15-28
Author(s):  
D Hellemann ◽  
P Tallberg ◽  
SL Aalto ◽  
M Bartoli ◽  
S Hietanen
Keyword(s):  
Baltic Sea ◽  
Water Temperature ◽  
Nitrate Reduction ◽  
Seasonal Cycle ◽  
Bottom Water ◽  
Muddy Sediment ◽  
The Baltic Sea ◽  
Bottom Water Temperature ◽  
The Baltic ◽  
Sandy Sediments

Current knowledge on the seasonality of benthic nitrate reduction pathways in the aphotic, density stratified coastal zone of the Baltic Sea is largely based on data from muddy sediments, neglecting the potential contribution of sandy sediments. To gain a more comprehensive understanding of seasonality in this part of the Baltic Sea coast, we measured rates of benthic denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) monthly in the ice-free period of 2016 in both sandy and muddy aphotic sediments, northwestern Gulf of Finland. No anammox was observed. The seasonal cycle of denitrification in both sediment types was related to the hydrography-driven development of bottom water temperature. The seasonal cycle of DNRA was less clear and likely connected to a combination of bottom water temperature, carbon to nitrogen ratio, and substrate competition with denitrification. Denitrification and DNRA rates were 50-80 and 20% lower in the sandy than in the muddy sediment. The share of DNRA in total nitrate reduction, however, was higher in the sandy than in the muddy sediment, being (by ~50%) the highest DNRA share in sandy sediments so far measured. Our data add to the small pool of published studies showing significant DNRA in both cold and/or sandy sediments and suggest that DNRA is currently underestimated in the Baltic coastal nitrogen filter. Our results furthermore emphasize that the various environmental conditions of a coastal habitat (light regime, hydrography, and geomorphology) affect biogeochemical element cycling and thus need to be considered in data interpretation.

scholarly journals Multidecadal dynamics of the Arctic copepod Limnocalanus macrurus in relation to environmental variability in the Baltic Sea

2019 ◽  
Vol 76 (7) ◽  
pp. 2427-2436 ◽  
Author(s):  
Heli Einberg ◽  
Riina Klais ◽  
Gunta Rubene ◽  
Georgs Kornilovs ◽  
Ivars Putnis ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Temperature ◽  
Environmental Variability ◽  
The Arctic ◽  
The Baltic Sea ◽  
Bottom Water Temperature ◽  
Limnocalanus Macrurus ◽  
The Baltic ◽  
Winter Severity

Abstract The Arctic Limnocalanus macrurus is a prominent representative of large copepods which performs several essential functions in freshwater and marine ecosystems. Being a cold stenotherm species, its distribution is primarily confined to deeper water layers. Based on the long-term observations from one of the largest spatially confined natural populations of this species in the Baltic Sea, we detected profound long-term variability of L. macrurus during 1958–2016: high abundances before the 1980s, then nearly disappearance in the 1990s and recovery in the 2000s. The main environmental parameters explaining the interannual variability of L. macrurus in spring were herring spawning stock biomass in preceding year, winter severity, and bottom water temperature in preceding summer. The effect of winter severity and water temperature was also non-linear. The sliding window correlation analysis pointed to a non-stationary relationship between the abundance of L. macrurus and the key variables. Given the observed pronounced seasonality in the population structure of L. macrurus (young stages dominated in the beginning of the year and only adults were left in the population in summer and autumn) we identified the dynamics of key environmental variables to understand this species under different ecosystem configurations and different combinations of drivers of change.

Environmental factors affecting recent benthic foraminiferal distribution in the south-eastern Baltic Sea

Baltica ◽  
2020 ◽  
Vol 33 (1) ◽  
pp. 58-70
Author(s):  
Ekaterina Ponomarenko ◽  
Viktor Krechik ◽  
Evgenia Dorokhova
Keyword(s):  
Organic Carbon ◽  
Baltic Sea ◽  
Benthic Foraminifera ◽  
Bottom Water ◽  
Environmental Parameters ◽  
Organic Carbon Content ◽  
The South ◽  
The Baltic Sea ◽  
South Eastern ◽  
The Baltic

The Baltic Sea is characterized by a restricted exchange of deep waters due to permanent stratification of the water column. The aim of the present study is to investigate the distribution of benthic foraminifera in the south-eastern part of the Baltic Sea in relation to environmental parameters. The distribution of benthic foraminifera was analyzed in 26 surface sediment samples collected in the south-eastern part of the Baltic Sea and in the Bornholm Basin during springtime and wintertime 2016. Foraminiferal diversity in the studied region was extremely low. Agglutinated specimens dominated the assemblages and were represented by small-sized individuals which belong to Psammosphaera, Pseudothurammina, Saccammina, and Reophax genera. Calcareous foraminifera were dominated by Cribroelphidium genus. Micropaleontological data were compared to the environmental parameters characterizing bottom water (temperature, salinity, and dissolved oxygen content) and substrate conditions (grain size composition and total organic carbon content). Higher foraminiferal concentrations and diversity were found in deeper parts of the study region where fine-grained sediments with a higher total organic carbon content were accumulated under stable hydrographical conditions. Calcareous tests were found only at the stations with elevated salinity, indicating that bottom water salinity is the main factor limiting the distribution of calcareous foraminifera. On the other hand, substrate parameters and hydrodynamic conditions appear to play a major role in the distribution of agglutinated foraminifera.

Effects of lure type, fish size and water temperature on hooking location and bleeding in northern pike (Esox lucius) angled in the Baltic Sea

2014 ◽  
Vol 157 ◽  
pp. 164-169 ◽  
Author(s):  
M. Stålhammar ◽  
T. Fränstam ◽  
J. Lindström ◽  
J. Höjesjö ◽  
R. Arlinghaus ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Temperature ◽  
Northern Pike ◽  
Esox Lucius ◽  
The Baltic Sea ◽  
Fish Size ◽  
Pike Esox Lucius ◽  
The Baltic

scholarly journals Large variations in iron input to an oligotrophic Baltic Sea estuary: impact on sedimentary phosphorus burial

2018 ◽  
Vol 15 (22) ◽  
pp. 6979-6996 ◽  
Author(s):  
Wytze K. Lenstra ◽  
Matthias Egger ◽  
Niels A. G. M. van Helmond ◽  
Emma Kritzberg ◽  
Daniel J. Conley ◽  
...  
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Reactive Transport ◽  
Bottom Water ◽  
Transport Model ◽  
Coastal Sediments ◽  
Estuarine Sediments ◽  
Water Salinity ◽  
The Baltic Sea ◽  
The Baltic

Abstract. Estuarine sediments are key sites for removal of phosphorus (P) from rivers and the open sea. Vivianite, an Fe(II)-P mineral, can act as a major sink for P in Fe-rich coastal sediments. In this study, we investigate the burial of P in the Öre Estuary in the northern Baltic Sea. We find much higher rates of P burial at our five study sites (up to ∼0.145 molm-2yr-1) when compared to more southern coastal areas in the Baltic Sea with similar rates of sedimentation. Detailed study of the sediment P forms at our site with the highest rate of sedimentation reveals a major role for P associated with Fe and the presence of vivianite crystals below the sulfate methane transition zone. By applying a reactive transport model to sediment and porewater profiles for this site, we show that vivianite may account for up to ∼40 % of total P burial. With the model, we demonstrate that vivianite formation is promoted in sediments with a low bottom water salinity and high rates of sedimentation and Fe oxide input. While high rates of organic matter input are also required, there is an optimum rate above which vivianite formation declines. Distinct enrichments in sediment Fe and sulfur at depth in the sediment are attributed to short periods of enhanced input of riverine Fe and organic matter. These periods of enhanced input are linked to variations in rainfall on land and follow dry periods. Most of the P associated with the Fe in the sediment is likely imported from the adjacent eutrophic Baltic Proper. Our work demonstrates that variations in land-to-sea transfer of Fe may act as a key control on burial of P in coastal sediments. Ongoing climate change is expected to lead to a decrease in bottom water salinity and contribute to continued high inputs of Fe oxides from land, further promoting P burial as vivianite in the coastal zone of the northern Baltic Sea. This may enhance the role of this oligotrophic area as a sink for P imported from eutrophic parts of the Baltic Sea.

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.

Size-dependent winter mortality of age-0 pikeperch (Stizostedion lucioperca) in Pärnu Bay, the Baltic Sea

2000 ◽  
Vol 57 (2) ◽  
pp. 451-458 ◽  
Author(s):  
Jyrki Lappalainen ◽  
Vaike Erm ◽  
Jakob Kjellman ◽  
Hannu Lehtonen
Keyword(s):  
Baltic Sea ◽  
Water Temperature ◽  
Ice Cover ◽  
Winter Mortality ◽  
The Baltic Sea ◽  
Size Dependent ◽  
The Baltic ◽  
Stizostedion Lucioperca ◽  
Dependent Mortality

Winter mortality of pikeperch (Stizostedion lucioperca) at age 0 is dependent on size, based on samples collected with trawls during 1961-1994 in Pärnu Bay, Estonia. Mortality increased as mean length of pikeperch in the first autumn decreased. The size-dependent mortality was analysed as correlation between mean lengths at age 0 in autumn and changes in mean lengths between age 1 and age 0. When the varying lengths at age 0 were taken into account, the duration of winter also affected mortality; longer durations of ice cover resulted in less size-dependent winter mortality. Since mean length at age 0 in autumn correlated positively with summer water temperature, winter mortality can be expected to decrease the warmer the summer.

scholarly journals Review and assessment of nitrate reduction in groundwater in the Baltic Sea Basin

2017 ◽  
Vol 12 ◽  
pp. 50-68 ◽  
Author(s):  
Anker Lajer Højberg ◽  
Anne Lausten Hansen ◽  
Przemysław Wachniew ◽  
Anna J. Żurek ◽  
Seija Virtanen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Nitrate Reduction ◽  
The Baltic Sea ◽  
The Baltic ◽  
Baltic Sea Basin

scholarly journals First Application of IFCB High-Frequency Imaging-in-Flow Cytometry to Investigate Bloom-Forming Filamentous Cyanobacteria in the Baltic Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Kaisa Kraft ◽  
Jukka Seppälä ◽  
Heidi Hällfors ◽  
Sanna Suikkanen ◽  
Pasi Ylöstalo ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Wind Speed ◽  
Baltic Sea ◽  
Water Temperature ◽  
High Frequency ◽  
Filamentous Cyanobacteria ◽  
Monitoring Methods ◽  
The Baltic Sea ◽  
Imaging Flow Cytometry ◽  
The Baltic

Cyanobacteria are an important part of phytoplankton communities, however, they are also known for forming massive blooms with potentially deleterious effects on recreational use, human and animal health, and ecosystem functioning. Emerging high-frequency imaging flow cytometry applications, such as Imaging FlowCytobot (IFCB), are crucial in furthering our understanding of the factors driving bloom dynamics, since these applications provide community composition information at frequencies impossible to attain using conventional monitoring methods. However, the proof of applicability of automated imaging applications for studying dynamics of filamentous cyanobacteria is still scarce. In this study we present the first results of IFCB applied to a Baltic Sea cyanobacterial bloom community using a continuous flow-through setup. Our main aim was to demonstrate the pros and cons of the IFCB in identifying filamentous cyanobacterial taxa and in estimating their biomass. Selected environmental parameters (water temperature, wind speed and salinity) were included, in order to demonstrate the dynamics of the system the cyanobacteria occur in and the possibilities for analyzing high-frequency phytoplankton observations against changes in the environment. In order to compare the IFCB results with conventional monitoring methods, filamentous cyanobacteria were enumerated from water samples using light microscopical analysis. Two common bloom forming filamentous cyanobacteria in the Baltic Sea, Aphanizomenon flosaquae and Dolichospermum spp. dominated the bloom, followed by an increase in Oscillatoriales abundance. The IFCB results compared well with the results of the light microscopical analysis, especially in the case of Dolichospermum. Aphanizomenon biomass varied slightly between the methods and the Oscillatoriales results deviated the most. Bloom formation was initiated as water temperature increased to over 15°C and terminated as the wind speed increased, dispersing the bloom. Community shifts were closely related to movements of the water mass. We demonstrate how using a high-frequency imaging flow cytometry application can help understand the development of cyanobacteria summer blooms.

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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