scholarly journals The diurnal cycle of <i>p</i>CO<sub>2</sub> in the coastal region of the Baltic Sea

Ocean Science ◽  
2021 ◽  
Vol 17 (6) ◽  
pp. 1657-1675
Author(s):  
Martti Honkanen ◽  
Jens Daniel Müller ◽  
Jukka Seppälä ◽  
Gregor Rehder ◽  
Sami Kielosto ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Baltic Sea ◽  
Diurnal Cycle ◽  
Coastal Region ◽  
Outer Edge ◽  
The Baltic Sea ◽  
Short Term ◽  
Biological Fixation ◽  
Carbon Dioxide Fluxes ◽  
The Baltic

Abstract. The direction and magnitude of carbon dioxide fluxes between the atmosphere and the sea are regulated by the gradient in the partial pressure of carbon dioxide (pCO2) across the air–sea interface. Typically, observations of pCO2 at the sea surface are carried out by using research vessels and ships of opportunity, which usually do not resolve the diurnal cycle of pCO2 at a given location. This study evaluates the magnitude and driving processes of the diurnal cycle of pCO2 in a coastal region of the Baltic Sea. We present pCO2 data from July 2018 to June 2019 measured in the vicinity of the island of Utö at the outer edge of the Archipelago Sea, and quantify the relevant physical, biological, and chemical processes controlling pCO2. The highest monthly median of diurnal pCO2 variability (31 µatm) was observed in August and predominantly driven by biological processes. Biological fixation and mineralization of carbon led to sinusoidal diurnal pCO2 variations, with a maximum in the morning and a minimum in the afternoon. Compared with the biological carbon transformations, the impacts of air–sea fluxes and temperature changes on pCO2 were small, with their contributions to the monthly medians of diurnal pCO2 variability being up to 12 and 5 µatm, respectively. During upwelling events, short-term pCO2 variability (up to 500 µatm within a day) largely exceeded the usual diurnal cycle. If the net annual air–sea flux of carbon dioxide at our study site and for the sampled period is calculated based on a data subset that consists of only one regular measurement per day, the bias in the net exchange depends on the sampling time and can amount up to ±12 %. This finding highlights the importance of continuous surface pCO2 measurements at fixed locations for the assessment of the short-term variability of the carbonate system and the correct determination of air–sea CO2 fluxes.

scholarly journals Diurnal cycle of the CO<sub>2</sub> system in the coastal region of the Baltic Sea

2020 ◽  
Author(s):  
Martti Honkanen ◽  
Jens Daniel Müller ◽  
Jukka Seppälä ◽  
Gregor Rehder ◽  
Sami Kielosto ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Baltic Sea ◽  
Diurnal Cycle ◽  
Coastal Region ◽  
Sampling Period ◽  
Effect Of Temperature ◽  
Carbon Dioxide Exchange ◽  
The Baltic Sea ◽  
Data Set ◽  
The Baltic

Abstract. The direction and magnitude of carbon dioxide exchange between the atmosphere and the sea is regulated by their difference in partial pressure of carbon dioxide (pCO2). Typically, observations of pCO2 are carried out by using research vessels and voluntary observing ships which cannot easily detect the diurnal cycle of pCO2 at a given location. This study evaluates the magnitude and driving processes of the diurnal cycle of pCO2 in a coastal region of the Baltic Sea during the different seasons.We present pCO2 data from July 2018–June 2019 carried out in the vicinity of the island of Utö in the Archipelago Sea and quantify the relevant physical, biological and chemical processes affecting pCO2. The highest monthly median diurnal pCO2 peak-to-peak amplitude (31 μatm) was observed in August. This high diurnal variation was found to be related predominantly to biological processes. The biological transformations of carbon generated a sinusoidal diurnal pCO2 variation, with a maximum in the morning and a minimum in the afternoon. Compared to the biological carbon transformations, the effect of air sea exchange of carbon dioxide and the effect of temperature changes on pCO2 are smaller, with their monthly median peak-to-peak amplitudes were up to 12 and 5 μatm, respectively. Single diurnal peak-to-peak amplitudes can be significantly larger (up to 500 μatm), during upwelling. If the net exchange of carbon dioxide between the sea and atmosphere on our study site and sampling period is calculated based on a data set that consists of only one measurement per day, the error in the budget depends on the sampling time and can be up to &amp;pm;12 %.

Behavioural responses of voles to simulated risk of predation by a native and an alien mustelid: an odour manipulation experiment

2010 ◽  
Vol 37 (4) ◽  
pp. 273 ◽  
Author(s):  
Karen Fey ◽  
Peter B. Banks ◽  
Hannu Ylönen ◽  
Erkki Korpimäki
Keyword(s):  
Baltic Sea ◽  
Predation Risk ◽  
Myodes Glareolus ◽  
The Baltic Sea ◽  
Short Term ◽  
Behavioural Responses ◽  
Alien Predator ◽  
Risk Of Predation ◽  
The Baltic ◽  
The Impact

Context. Potential mammalian prey commonly use the odours of their co-evolved predators to manage their risks of predation. But when the risk comes from an unknown source of predation, odours might not be perceived as dangerous, and anti-predator responses may fail, except possibly if the alien predator is of the same archetype as a native predator. Aims. In the present study we examined anti-predator behavioural responses of voles from the outer archipelagos of the Baltic Sea, south-western Finland, where they have had no resident mammalian predators in recent history. Methods. We investigated responses of field voles (Microtus agrestis) to odours of native least weasels (Mustela nivalis) and a recently invading alien predator, the American mink (Mustela vison), in laboratory. We also studied the short-term responses of free-ranging field voles and bank voles (Myodes glareolus) to simulated predation risk by alien mink on small islands in the outer archipelago of the Baltic Sea. Key results. In the laboratory, voles avoided odour cues of native weasel but not of alien mink. It is possible that the response to mink is a context dependent learned response which could not be induced in the laboratory, whereas the response to weasel is innate. In the field, however, voles reduced activity during their normal peak-activity times at night as a response to simulated alien-mink predation risk. No other shifts in space use or activity in safer microhabitats or denser vegetation were apparent. Conclusions. Voles appeared to recognise alien minks as predators from their odours in the wild. However, reduction in activity is likely to be only a short-term immediate response to mink presence, which is augmented by longer-term strategies of habitat shift. Because alien mink still strongly suppresses vole dynamics despite these anti-predator responses, we suggest that behavioural naiveté may be the primary factor in the impact of an alien predator on native prey. Implications. Prey naiveté has long been considered as the root cause of the devastating impacts of alien predators, whereby native prey simply fail to recognise and respond to the novel predation risk. Our results reveal a more complex form of naiveté whereby native prey appeared to recognise alien predators as a threat but their response is ultimately inadequate. Thus, recognition alone is unlikely to afford protection for native prey from alien-predator impacts. Thus, management strategies that, for example, train prey in recognition of novel threats must induce effective responses if they are expected to succeed.

Nitrogen fixation in a diazotrophic post-bloom situation in the Baltic Sea

2021 ◽  
Author(s):  
Christian Reeder ◽  
Carolin Löscher
Keyword(s):  
Climate Change ◽  
Surface Water ◽  
Baltic Sea ◽  
The Baltic Sea ◽  
Biological Fixation ◽  
Community Based ◽  
Iron Iron ◽  
The Baltic ◽  
Metal Cofactors ◽  
Diazotrophic Community

&lt;p&gt;The Baltic Sea is characterised as a semi-enclosed brackish Sea that has experienced increased eutrophication, hypoxia, and increased temperature over the last ~100 years making Baltic Sea one of the most severely impacted oceanic environment by climate change. Biological fixation of dinitrogen gas (N&lt;sub&gt;2&lt;/sub&gt;) is an essential process to make atmospheric N&lt;sub&gt;2&lt;/sub&gt; available for marine life. This process is carried out by specialised organisms called diazotrophs and is catalysed by the energetic-consuming enzyme nitrogenase. Nitrogenases exist in three subtypes depending on their metal cofactors, (1) the most common molybdenum-dependent (Nif), (2) the vanadium-dependent (Vnf) and (3) the Iron-Iron-dependent nitrogenase (Anf). To date, the effect of climate change on those three enzyme subtypes and their potential role a future ocean is yet to be explored. The predicted ongoing oxygen loss in the ocean may limit Mo's availability and trigger a shift from the abundant Nif-type nitrogenase to Vnf or Anf and, therefore, a potential shift in the diazotrophic community. This study explored the climate change-related pressures on N&lt;sub&gt;2&lt;/sub&gt; fixation and the diazotrophic community based on nifH and vnf/anfD amplicons. At the time of sampling, we found a post-bloom high-nutrient low-chlorophyll situation. Cyanobacterial groups, Nodularia and UCYN-A, dominated the diazotrophic community and showed a horizontal where UCYN-A were the dominant fixers at 20 m. Based on alternative nitrogenases amplicons, Rhodopseudomonas was the dominating microbe in the surface water. This paper presents the first hint of active nitrogenases in surface water and further establish UCYN-A as a significant player in Baltic Sea primary production.&lt;/p&gt;

Sea level variations in the coastal region from altimetry – Using optimal interpolation in the Baltic Sea for 3-day mean sea level from altimetry, tide gauge and model data

2021 ◽  
Author(s):  
Ida Margrethe Ringgaard ◽  
Jacob L. Høyer ◽  
Kristine S. Madsen ◽  
Adili Abulaitijiang ◽  
Ole B. Andersen
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Temporal Resolution ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Coastal Region ◽  
Optimal Interpolation ◽  
The Baltic Sea ◽  
Spatial Coverage ◽  
The Baltic

&lt;p&gt;The rise and fall of the sea surface in the coastal region is observed closely by two different sources: tide gauges measure the relative sea level anomaly at the coast at high temporal resolution (minutes or hours) and satellite altimeters measure the absolute sea surface height of the open ocean along tracks multiple times a day. However, these daily tracks are scattered across the Baltic Sea with each track being repeated at a lower temporal resolution (days). Due to the inverse relationship between spatial and temporal coverage of the satellite altimetry data, gridded satellite altimetry products often prioritize spatial coverage over temporal resolution, thus filtering out the high sea level variability. In other words, the satellite data, and especially averaged products, often miss the daily sea level variability, such as storm surges, which is most important for all societies in the coastal region. To compensate for the sparse spatial coverage from satellite altimetry, we here present an experimental product developed as part of the ESA project Baltic+SEAL: &amp;#160;on a 3-day scale, the DMI Optimal Interpolation (DMI-OI) method is combined with error statistics from a storm surge model as well as 3-day averages from both tide gauge observations and satellite altimetry tracks to generate a gridded sea level anomaly product for the Baltic Sea for year 2017. The product captures the overall temporal evolution of the sea level changes well for most areas with an average RMSE wrt. tide gauge observations of 17.2 cm and a maximum of 34.2 cm. Thus, the 3-day mean gridded product shows potential as an alternative to monthly altimetry products, although further work is needed.&lt;/p&gt;

Modelling the uptake and release of carbon dioxide in the Baltic Sea surface water

2009 ◽  
Vol 29 (7) ◽  
pp. 870-885 ◽  
Author(s):  
Anders Omstedt ◽  
Erik Gustafsson ◽  
Karin Wesslander
Keyword(s):  
Carbon Dioxide ◽  
Surface Water ◽  
Baltic Sea ◽  
Sea Surface ◽  
The Baltic Sea ◽  
The Baltic ◽  
Uptake And Release

scholarly journals Shifts in the microbial community in the Baltic Sea with increasing CO<sub>2</sub>

2016 ◽  
Author(s):  
K .J. Crawfurd ◽  
C .P. D. Brussaard ◽  
U. Riebesell
Keyword(s):  
Carbon Dioxide ◽  
Microbial Community ◽  
Ocean Acidification ◽  
Baltic Sea ◽  
Community Dynamics ◽  
The Other ◽  
The Baltic Sea ◽  
Viral Lysis ◽  
Large Shift ◽  
The Baltic

Abstract. Ocean acidification, due to dissolution of anthropogenically produced carbon dioxide is considered a major threat to marine ecosystems. The Baltic Sea, with extremely low salinity and thus low pH buffering capacity, is likely to experience stronger variation in pH than the open ocean with increasing atmospheric carbon dioxide. We examined the effects of ocean acidification on the microbial community during summer using large volume in situ mesocosms to simulate present to future and far future scenarios. We saw distinct trends with increasing CO2 in each of the 6 groups of phytoplankton with diameters below 20 μm that we enumerated by flow cytometry. Of these groups two picoeukaryotic groups increased in abundance whilst the other groups, including prokaryotic Synechococcus spp., decreased with increasing CO2. Gross growth rates increased with increasing CO2 in the dominant picoeukaryote group sufficient to double their abundances whilst reduced grazing allowed the other picoeukaryotes to flourish at higher CO2. Significant increases in lysis rates were seen at higher CO2 in these two picoeukaryote groups. Converting abundances to particulate organic carbon we saw a large shift in the partitioning of carbon between the size fractions which lasted throughout the experiment. The heterotrophic prokaryotes largely followed the algal biomass with responses to increasing CO2 reflecting the altered phytoplankton community dynamics. Similarly, higher viral abundances at higher CO2 seemed related to increased prokaryote biomass. Viral lysis and grazing were equally important controlling prokaryotic abundances. Overall our results point to a shift towards a more regenerative system with potentially increased productivity but reduced carbon export.

scholarly journals Sensitivity of the air–sea CO<sub>2</sub> exchange in the Baltic Sea and Danish inner waters to atmospheric short term variability

2014 ◽  
Vol 11 (12) ◽  
pp. 16993-17042
Author(s):  
A. S. Lansø ◽  
J. Bendtsen ◽  
J. H. Christensen ◽  
L. L. Sørensen ◽  
H. Chen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Co2 Exchange ◽  
Atmospheric Co2 ◽  
The Baltic Sea ◽  
Short Term ◽  
Transfer Velocity ◽  
The Baltic ◽  
Short Term Variability

Abstract. Minimising the uncertainties in estimates of air–sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air–sea CO2 flux along with its sensitivity to e.g. short-term temporal variability in wind speed, atmospheric mixing height and the atmospheric CO2 concentration. With this study the importance of high spatiotemporal resolution of atmospheric parameters for the air–sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2) has been developed for this coastal area based on available data from monitoring stations and underway pCO2 measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air–sea CO2 flux. Two model simulations were conducted – one including short term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air–sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005–2010 the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish Straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short term variability in atmospheric CO2 does have a sizeable effect on the air–sea CO2 exchange. The combination of the atmospheric model and the new pCO2 fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air–sea CO2 flux in particular caused by the transfer velocity parameterisation and the applied pCO2 climatology. However, the present study underlines the importance of including short term variability in the atmospheric CO2 concentration in future model studies of the air–sea exchange in order to minimise the uncertainty.

Dynamics of halocarbons in coastal surface waters during short term mesocosm experiments

2015 ◽  
Vol 12 (4) ◽  
pp. 515 ◽  
Author(s):  
Anna Orlikowska ◽  
Christian Stolle ◽  
Falk Pollehne ◽  
Klaus Jürgens ◽  
Detlef E. Schulz-Bull
Keyword(s):  
Ultraviolet Radiation ◽  
Baltic Sea ◽  
Surface Waters ◽  
Diurnal Changes ◽  
The Baltic Sea ◽  
Short Term ◽  
Δ13c Values ◽  
Natural Systems ◽  
Mesocosm Experiments ◽  
The Baltic

Environmental context Halocarbons are trace gases important in atmospheric ozone chemistry whose biogenic production – among other factors – depends on light-induced stress of marine algae. Several studies have confirmed this effect in laboratory experiments but knowledge in natural systems remains sparse. In mesocosm experiments, which are a link between field and laboratory studies, we observed that the influence of natural levels of ultraviolet radiation on halocarbon dynamics in the marine surface waters was either insignificant or concealed by the complex interactions in the natural systems. Abstract The aim of the present study was to evaluate the influence of different light quality, especially ultraviolet radiation (UVR), on the dynamics of volatile halogenated organic compounds (VHOCs) at the sea surface. Short term experiments were conducted with floating gas-tight mesocosms of different optical qualities. Six halocarbons (CH3I, CHCl3, CH2Br2, CH2ClI, CHBr3 and CH2I2), known to be produced by phytoplankton, together with a variety of biological and environmental variables were measured in the coastal southern Baltic Sea and in the Raunefjord (North Sea). These experiments showed that ambient levels of UVR have no significant influence on VHOC dynamics in the natural systems. We attribute it to the low radiation doses that phytoplankton cells receive in a normal turbulent surface mixed layer. The VHOC concentrations were influenced by their production and removal processes, but they were not correlated with biological or environmental parameters investigated. Diatoms were most likely the dominant biogenic source of VHOCs in the Baltic Sea experiment, whereas in the Raunefjord experiment macroalgae probably contributed strongly to the production of VHOCs. The variable stable carbon isotope signatures (δ13C values) of bromoform (CHBr3) also indicate that different autotrophic organisms were responsible for CHBr3 production in the two coastal environments. In the Raunefjord, despite strong daily variations in CHBr3 concentration, the carbon isotopic ratio was fairly stable with a mean value of –26‰. During the declining spring phytoplankton bloom in the Baltic Sea, the δ13C values of CHBr3 were enriched in 13C and showed noticeable diurnal changes (–12‰ ±4). These results show that isotope signature analysis is a useful tool to study both the origin and dynamics of VHOCs in natural systems.

Seasonal variability of phytoplankton in river Słupia of the southern Baltic Sea

2018 ◽  
Vol 33 (1) ◽  
pp. 139-148
Author(s):  
Iwona Zabroś ◽  
Marlena Mioskowska
Keyword(s):  
Baltic Sea ◽  
Coastal Region ◽  
Environmental Parameters ◽  
Annual Reports ◽  
Spatial And Temporal Variability ◽  
Total Biomass ◽  
Phytoplankton Abundance ◽  
The Baltic Sea ◽  
Southern Baltic ◽  
The Baltic

In the Baltic Sea, there can be observed seasonal variations in the structure of phytoplankton. These organisms are particularly sensitive to changes in different environmental parameters. The consequence of these changes is cyclical repeated every year fluctuation of the species composition, their abundance and biomass of phytoplankton. The spatial and temporal variability of individual phytoplankton groups is not the same in different regions of the Baltic Sea, and this is why the study was conducted in the area of the central Baltic coast, since in that particular region data on phytoplankton is not available. One of the main goals was to determine the temporal and spatial structure of the occurrence of phytoplankton, as well as to study biodiversity in the area of the estuary of the Slupia river in southern Baltic for the period between November 2014 and September 2016. The results of the research confirm typical changes of phytoplankton in three studied areas depending on the given season. The average values of phytoplankton abundance and biomass were typical for this kind of coastal waters and there were no significant species differences between these stations. The only research (and available studies) on phytoplankton in central sea basin areas is being conducted by Institute of Meteorology and Water Management (IMWM) as part of the HELCOM Baltic Sea Monitoring at station P16, which is the closest location to the studied area. When comparing the results obtained in this study to the data from the IMWM annual reports for the last decade, it can be noticed that the size and fluctuations of total biomass and phytoplankton abundance in the three studied areas are typical for the coastal region of the South Baltic.

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