scholarly journals Effect of elevated CO<sub>2</sub> on organic matter pools and fluxes in a summer Baltic Sea plankton community

2015 ◽  
Vol 12 (20) ◽  
pp. 6181-6203 ◽  
Author(s):  
A. J. Paul ◽  
L. T. Bach ◽  
K.-G. Schulz ◽  
T. Boxhammer ◽  
J. Czerny ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Matter ◽  
Ocean Acidification ◽  
Baltic Sea ◽  
Water Column ◽  
Chlorophyll A ◽  
Plankton Community ◽  
Phase Iii ◽  
The Baltic Sea ◽  
The Baltic

Abstract. Ocean acidification is expected to influence plankton community structure and biogeochemical element cycles. To date, the response of plankton communities to elevated CO2 has been studied primarily during nutrient-stimulated blooms. In this CO2 manipulation study, we used large-volume (~ 55 m3) pelagic in situ mesocosms to enclose a natural summer, post-spring-bloom plankton assemblage in the Baltic Sea to investigate the response of organic matter pools to ocean acidification. The carbonate system in the six mesocosms was manipulated to yield average fCO2 ranging between 365 and ~ 1230 μatm with no adjustment of naturally available nutrient concentrations. Plankton community development and key biogeochemical element pools were subsequently followed in this nitrogen-limited ecosystem over a period of 7 weeks. We observed higher sustained chlorophyll a and particulate matter concentrations (~ 25 % higher) and lower inorganic phosphate concentrations in the water column in the highest fCO2 treatment (1231 μatm) during the final 2 weeks of the study period (Phase III), when there was low net change in particulate and dissolved matter pools. Size-fractionated phytoplankton pigment analyses indicated that these differences were driven by picophytoplankton (< 2 μm) and were already established early in the experiment during an initial warm and more productive period with overall elevated chlorophyll a and particulate matter concentrations. However, the influence of picophytoplankton on bulk organic matter pools was masked by high biomass of larger plankton until Phase III, when the contribution of the small size fraction (< 2 μm) increased to up to 90 % of chlorophyll a. In this phase, a CO2-driven increase in water column particulate carbon did not lead to enhanced sinking material flux but was instead reflected in increased dissolved organic carbon concentrations. Hence ocean acidification may induce changes in organic matter partitioning in the upper water column during the low-nitrogen summer period in the Baltic Sea.

scholarly journals Effect of elevated CO<sub>2</sub> on organic matter pools and fluxes in a summer, post spring-bloom Baltic Sea plankton community

2015 ◽  
Vol 12 (9) ◽  
pp. 6863-6927 ◽  
Author(s):  
A. J. Paul ◽  
L. T. Bach ◽  
K.-G. Schulz ◽  
T. Boxhammer ◽  
J. Czerny ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Matter ◽  
Phase I ◽  
Ocean Acidification ◽  
Baltic Sea ◽  
Water Column ◽  
Chlorophyll A ◽  
Spring Bloom ◽  
Plankton Community ◽  
Phase Iii

Abstract. Ocean acidification is expected to influence plankton community structure and biogeochemical element cycles. To date, experiments with nutrient stimulated blooms have been primarily used to study the response of plankton communities to elevated CO2. In this CO2 manipulation study, we used large-volume (~55 m3) pelagic in situ mesocosms to enclose a natural, post spring-bloom plankton assemblage in the Baltic Sea to investigate the response of organic matter pools to ocean acidification. In the mesocosms, fCO2 was manipulated yielding a range of average fCO2 of 365 to ~1231 μatm with no adjustment of naturally available nutrient concentrations. Plankton community development and key biogeochemical element pools were subsequently followed in this nitrogen-limited ecosystem over a period of seven weeks. We identified three distinct phases based on temperature fluctuations and plankton biomass: a warm, productive period with elevated chlorophyll a and particulate matter concentrations (Phase I), a decline in autotrophic biomass coinciding with cooler water temperatures associated with lower incoming photosynthetically active radiation (PAR) and higher zooplankton grazing pressure (Phase II), and a steady state phase with low net change in particulate and dissolved matter pools (Phase III). We observed higher sustained chlorophyll a and particulate matter concentrations (~25% higher) and lower inorganic phosphate concentrations in the water column in the highest fCO2 treatment (1231 μatm) in Phase III. Size-fractionated phytoplankton pigment analyses indicated that these differences were driven by picophytoplankton (< 2 μm) and were already established early in the experiment during Phase I. However the influence of picophytoplankton on bulk organic matter pools was masked by high biomass of larger plankton until Phase III when the small size fraction (< 2 μm) contributed up to 90% of chlorophyll a. Furthermore, CO2-related differences in water column suspended matter concentrations were not reflected in sinking material flux. Our results from this study indicate that ocean acidification could have significant and sustained impacts on pelagic biogeochemical element pools in nitrogen-limited ecosystems.

scholarly journals Parameterization of the light absorption properties of chromophoric dissolved organic matter in the Baltic Sea and Pomeranian lakes

Ocean Science ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 1013-1032 ◽  
Author(s):  
Justyna Meler ◽  
Piotr Kowalczuk ◽  
Mirosława Ostrowska ◽  
Dariusz Ficek ◽  
Monika Zabłocka ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Absorption Coefficient ◽  
Baltic Sea ◽  
Chlorophyll A ◽  
Chromophoric Dissolved Organic Matter ◽  
The Baltic Sea ◽  
Absorption Properties ◽  
Chlorophyll A Concentration ◽  
The Baltic

Abstract. This study presents three alternative models for estimating the absorption properties of chromophoric dissolved organic matter aCDOM(λ). For this analysis we used a database containing 556 absorption spectra measured in 2006–2009 in different regions of the Baltic Sea (open and coastal waters, the Gulf of Gdańsk and the Pomeranian Bay), at river mouths, in the Szczecin Lagoon and also in three lakes in Pomerania (Poland) – Obłęskie, Łebsko and Chotkowskie. The variability range of the chromophoric dissolved organic matter (CDOM) absorption coefficient at 400 nm, aCDOM(400), lay within 0.15–8.85 m−1. The variability in aCDOM(λ) was parameterized with respect to the variability over 3 orders of magnitude in the chlorophyll a concentration Chl a (0.7–119 mg m−3). The chlorophyll a concentration and aCDOM(400) were correlated, and a statistically significant, nonlinear empirical relationship between these parameters was derived (R2 =  0.83). On the basis of the covariance between these parameters, we derived two empirical mathematical models that enabled us to design the CDOM absorption coefficient dynamics in natural waters and reconstruct the complete CDOM absorption spectrum in the UV and visible spectral domains. The input variable in the first model was the chlorophyll a concentration, and in the second one it was aCDOM(400). Both models were fitted to a power function, and a second-order polynomial function was used as the exponent. Regression coefficients for these formulas were determined for wavelengths from 240 to 700 nm at 5 nm intervals. Both approximations reflected the real shape of the absorption spectra with a low level of uncertainty. Comparison of these approximations with other models of light absorption by CDOM demonstrated that our parameterizations were superior (bias from −1.45 to 62 %, RSME from 22 to 220 %) for estimating CDOM absorption in the optically complex waters of the Baltic Sea and Pomeranian lakes.

scholarly journals No observed effect of ocean acidification on nitrogen biogeochemistry in a summer Baltic Sea plankton community

2016 ◽  
Vol 13 (13) ◽  
pp. 3901-3913 ◽  
Author(s):  
Allanah J. Paul ◽  
Eric P. Achterberg ◽  
Lennart T. Bach ◽  
Tim Boxhammer ◽  
Jan Czerny ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Baltic Sea ◽  
N2 Fixation ◽  
Spring Bloom ◽  
Plankton Community ◽  
Organic N ◽  
Filamentous Cyanobacteria ◽  
The Baltic Sea ◽  
N Supply ◽  
The Baltic

Abstract. Nitrogen fixation by filamentous cyanobacteria supplies significant amounts of new nitrogen (N) to the Baltic Sea. This balances N loss processes such as denitrification and anammox, and forms an important N source supporting primary and secondary production in N-limited post-spring bloom plankton communities. Laboratory studies suggest that filamentous diazotrophic cyanobacteria growth and N2-fixation rates are sensitive to ocean acidification, with potential implications for new N supply to the Baltic Sea. In this study, our aim was to assess the effect of ocean acidification on diazotroph growth and activity as well as the contribution of diazotrophically fixed N to N supply in a natural plankton assemblage. We enclosed a natural plankton community in a summer season in the Baltic Sea near the entrance to the Gulf of Finland in six large-scale mesocosms (volume ∼ 55 m3) and manipulated fCO2 over a range relevant for projected ocean acidification by the end of this century (average treatment fCO2: 365–1231 µatm). The direct response of diazotroph growth and activity was followed in the mesocosms over a 47 day study period during N-limited growth in the summer plankton community. Diazotrophic filamentous cyanobacteria abundance throughout the study period and N2-fixation rates (determined only until day 21 due to subsequent use of contaminated commercial 15N-N2 gas stocks) remained low. Thus estimated new N inputs from diazotrophy were too low to relieve N limitation and stimulate a summer phytoplankton bloom. Instead, regeneration of organic N sources likely sustained growth in the plankton community. We could not detect significant CO2-related differences in neither inorganic nor organic N pool sizes, or particulate matter N : P stoichiometry. Additionally, no significant effect of elevated CO2 on diazotroph activity was observed. Therefore, ocean acidification had no observable impact on N cycling or biogeochemistry in this N-limited, post-spring bloom plankton assemblage in the Baltic Sea.

scholarly journals Parameterization of the light absorption properties of chromophoric dissolved organic matter in the Baltic Sea and Pomeranian Lakes

2016 ◽  
Author(s):  
Justyna Meler ◽  
Piotr Kowalczuk ◽  
Mirosława Ostrowska ◽  
Dariusz Ficek ◽  
Monika Zabłocka ◽  
...  
Keyword(s):  
Organic Matter ◽  
Absorption Coefficient ◽  
Baltic Sea ◽  
Chlorophyll A ◽  
Light Absorption ◽  
Chromophoric Dissolved Organic Matter ◽  
The Baltic Sea ◽  
Absorption Properties ◽  
Chlorophyll A Concentration ◽  
The Baltic

Abstract. This study presents three alternative models for estimation of absorption properties of Chromophoric Dissolved Organic Matter, aCDOM(l). For this analysis we used a database containing 556 absorption spectra measured in 2006–2009 in different regions of the Baltic Sea (open and coastal waters, the Gulf of Gdańsk and the Pomeranian Bay), at river mouths, in the Szczecin Lagoon and also in three Pomeranian lakes in Poland – Lakes Obłęskie, Łebsko and Chotkowskie. Observed variability range of the CDOM absorption coefficient at 400 nm, aCDOM(400), contained within 0.15–8.85 m−1. The variability in aCDOM(l) was parameterized with respect to three orders of magnitude variability in the chlorophyll a concentration Chla (0.7–119 mg m−3). Chlorophyll a concentration and CDOM absorption coefficient, aCDOM(400) were correlated, and statistically significant, non-linear empirical relationship between those parameters was derived (R2 = 0.83). Based on observed co-variance between these parameters, we derived two empirical mathematical models that enabled to project the CDOM absorption coefficient dynamics in natural waters and reconstruct the completed CDOM absorption spectrum in the UV and visible spectral domains. The first model used the chlorophyll a concentration as the input variable. The second model used the aCDOM(400), as the input variable. Both models were fitted to power function and the second order polynomial function was used as the exponent. Regression coefficients for derived formulas were determined for wavelengths from 240 to 700 nm at 5 nm intervals . Both approximation reflected the real shape of the absorption spectra with low uncertainty. Comparison of these approximation with other models of light absorption by CDOM proved that proposed parameterizations were better (bias from −1.45 % to 62 %, RSME from 22 % to 220 %) for estimation CDOM absorption in optically complex waters of the Baltic Sea and lakes.

scholarly journals No observed effect of ocean acidification on nitrogen biogeochemistry in a summer Baltic Sea plankton community

2015 ◽  
Vol 12 (20) ◽  
pp. 17507-17541 ◽  
Author(s):  
A. J. Paul ◽  
E. P. Achterberg ◽  
L. T. Bach ◽  
T. Boxhammer ◽  
J. Czerny ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Baltic Sea ◽  
N2 Fixation ◽  
Spring Bloom ◽  
Plankton Community ◽  
Organic N ◽  
Filamentous Cyanobacteria ◽  
The Baltic Sea ◽  
N Supply ◽  
The Baltic

Abstract. Nitrogen fixation by filamentous cyanobacteria supplies significant amounts of new nitrogen (N) to the Baltic Sea. This balances N loss processes such as denitrification and anammox and forms an important N source supporting primary and secondary production in N-limited post-spring bloom plankton communities. Laboratory studies suggest that filamentous diazotrophic cyanobacteria growth and N2-fixation rates are sensitive to ocean acidification with potential implications for new N supply to the Baltic Sea. In this study, our aim was to assess the effect of ocean acidification on diazotroph growth and activity as well as the contribution of diazotrophically-fixed N to N supply in a natural plankton assemblage. We enclosed a natural plankton community in a summer season in the Baltic Sea near the entrance to the Gulf of Finland in six large-scale mesocosms (volume ~ 55 m3) and manipulated fCO2 over a range relevant for projected ocean acidification by the end of this century (average treatment fCO2: 365–1231 μatm). The direct response of diazotroph growth and activity was followed in the mesocosms over a 47 day study period during N-limited growth in the summer plankton community. Diazotrophic filamentous cyanobacteria abundance throughout the study period and N2-fixation rates (determined only until day 21 due to subsequent use of contaminated commercial 15N-N2 gas stocks) remained low. Thus estimated new N inputs from diazotrophy were too low to relieve N limitation and stimulate a summer phytoplankton bloom. Instead regeneration of organic N sources likely sustained growth in the plankton community. We could not detect significant CO2-related differences in inorganic or organic N pools sizes, or particulate matter N : P stoichiometry. Additionally, no significant effect of elevated CO2 on diazotroph activity was observed. Therefore, ocean acidification had no observable impact on N cycling or biogeochemistry in this N-limited, post-spring bloom plankton assemblage in the Baltic Sea.

scholarly journals Cell-free extracellular enzymatic activity is linked to seasonal temperature changes: a case study in the Baltic Sea

2016 ◽  
Vol 13 (9) ◽  
pp. 2815-2821 ◽  
Author(s):  
Federico Baltar ◽  
Catherine Legrand ◽  
Jarone Pinhassi
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Extracellular Enzymes ◽  
Seasonal Pattern ◽  
Critical Factor ◽  
Hydrolytic Activity ◽  
Seasonal Temperature ◽  
The Baltic Sea ◽  
The Baltic ◽  
Hydrolysis Of

Abstract. Extracellular enzymatic activities (EEAs) are a crucial step in the degradation of organic matter. Dissolved (cell-free) extracellular enzymes in seawater can make up a significant contribution of the bulk EEA. However, the factors controlling the proportion of dissolved EEA in the marine environment remain unknown. Here we studied the seasonal changes in the proportion of dissolved relative to total EEA (of alkaline phosphatase (APase), β-glucosidase (BGase), and leucine aminopeptidase (LAPase)), in the Baltic Sea for 18 months. The proportion of dissolved EEA ranged between 37 and 100, 0 and 100, and 34 and 100 % for APase, BGase, and LAPase, respectively. A consistent seasonal pattern in the proportion of dissolved EEA was found among all the studied enzymes, with values up to 100 % during winter and  <  40 % during summer. A significant negative relation was found between the proportion of dissolved EEA and temperature, indicating that temperature might be a critical factor controlling the proportion of dissolved relative to total EEA in marine environments. Our results suggest a strong decoupling of hydrolysis rates from microbial dynamics in cold waters. This implies that under cold conditions, cell-free enzymes can contribute to substrate availability at large distances from the producing cell, increasing the dissociation between the hydrolysis of organic compounds and the actual microbes producing the enzymes. This might also suggest a potential effect of global warming on the hydrolysis of organic matter via a reduction of the contribution of cell-free enzymes to the bulk hydrolytic activity.

scholarly journals Pectenotoxin-2 and dinophysistoxin-1 in suspended and sedimenting organic matter in the Baltic Sea

2006 ◽  
Vol 51 (5) ◽  
pp. 2300-2307 ◽  
Author(s):  
Pirjo Kuuppo ◽  
Pauliina Uronen ◽  
Anika Petermann ◽  
Timo Tamminen ◽  
Edna Granéli
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
The Baltic Sea ◽  
The Baltic ◽  
Pectenotoxin 2
Sign in / Sign up

Export Citation Format

Share Document