Modeling the growth rates of cyanobacteria and diatoms in the Baltic Sea

Potential influences of various environmental factors on phytoplankton growth rates in the Baltic Sea are discussed. Our focus is on quantitative comparisons of growth rates of two phytoplankton functional types, diatoms and cyanobacteria. Growth rates are calculated as a function of quanta absorbed by phytoplankton. This in turn depends on phytoplankton exposition to light, which was simulated to represent realistic conditions encountered in the Baltic Sea in summer. In addition, phytoplankton absorption capability was characterized by absorption coefficients derived from measurements on phytoplankton mono-cultures isolated from the Baltic Sea. Estimated exposition of phytoplankton to photosynthetically available radiation (PAR) in surface waters can change about five times in case of the same solar surface insolation and water turbidity, solely due to changes in the mixed layer depth from 2 to 20 meters. When additionally changes in water turbidity are considered, phytoplankton PAR exposition can change by one order of magnitude. Light exposition and absorption properties of phytoplankton determine the effectiveness of light absorption. In our simulations for the same species of phytoplankton, changes in light exposition resulted in differences of an order of magnitude of absorbed quanta. The importance of accounting for absorptive properties is underlined through comparisons of the number of quanta absorbed by different phytoplankton types in the same environmental conditions. The effectiveness of light absorption translates to different growth rates achieved by each phytoplankton type. Our results support the notion that knowledge about phytoplankton absorption properties and light exposition is crucial when modeling phytoplankton in the Baltic Sea. Further progress is currently hindered by a lack of systematic information about maximum phytoplankton growth rates and their responses to specific environmental conditions for different functional types. Such information should be inferred in the future in specially designed laboratory experiments, that encompass realistic ranges of phytoplankton exposition to light, nutrients, temperatures and other conditions. This work has been funded by the National Science Centre (contract number: 2017/25/B/ST10/00159 entitled: &#8220;Numerical simulations of biological-physical interactions and phytoplankton cycles in the Baltic Sea&#8221;) and by the statutory funds of IOPAN.

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

10.5194/os-2016-34 ◽

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.

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A three-dimensional view on biodiversity changes: spatial, temporal, and functional perspectives on fish communities in the Baltic Sea

ICES Journal of Marine Science ◽

10.1093/icesjms/fsy027 ◽

2018 ◽

Vol 75 (7) ◽

pp. 2463-2475 ◽

Cited By ~ 3

Author(s):

Romain Frelat ◽

Alessandro Orio ◽

Michele Casini ◽

Andreas Lehmann ◽

Bastien Mérigot ◽

...

Keyword(s):

Baltic Sea ◽

Environmental Conditions ◽

Environmental Changes ◽

Temporal Dynamics ◽

Marine Ecosystem ◽

Fish Communities ◽

The Baltic Sea ◽

Functional Richness ◽

Holistic Understanding ◽

The Baltic

Abstract Fisheries and marine ecosystem-based management requires a holistic understanding of the dynamics of fish communities and their responses to changes in environmental conditions. Environmental conditions can simultaneously shape the spatial distribution and the temporal dynamics of a population, which together can trigger changes in the functional structure of communities. Here, we developed a comprehensive framework based on complementary multivariate statistical methodologies to simultaneously investigate the effects of environmental conditions on the spatial, temporal and functional dynamics of species assemblages. The framework is tested using survey data collected during more than 4000 fisheries hauls over the Baltic Sea between 2001 and 2016. The approach revealed the Baltic fish community to be structured into three sub-assemblages along a strong and temporally stable salinity gradient decreasing from West to the East. Additionally, we highlight a mismatch between species and functional richness associated with a lower functional redundancy in the Baltic Proper compared with other sub-areas, suggesting an ecosystem more susceptible to external pressures. Based on a large dataset of community data analysed in an innovative and comprehensive way, we could disentangle the effects of environmental changes on the structure of biotic communities—key information for the management and conservation of ecosystems.

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Mixing in the Baltic Sea and Implications for the Environmental Conditions

Hydrodynamics of Semi-Enclosed Seas, Proceedings of the 13th International Liege Colloquium on Ocean Hydrodynamics - Elsevier Oceanography Series ◽

10.1016/s0422-9894(08)71252-2 ◽

1982 ◽

pp. 399-418 ◽

Cited By ~ 2

Author(s):

Gunner Kullenberg

Keyword(s):

Baltic Sea ◽

Environmental Conditions ◽

The Baltic Sea ◽

The Baltic

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

Ocean Science ◽

10.5194/os-12-1013-2016 ◽

2016 ◽

Vol 12 (4) ◽

pp. 1013-1032 ◽

Cited By ~ 12

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.

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