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Distributions of photosynthetic and photoprotecting pigment concentrations in the water column in the Baltic Sea : an improved mathematical description

Stoń-Egiert Joanna, Majchrowski Roman, Ostrowska Mirosława

Oceanologia

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2019

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No. 61 (1)

1--16

EN

Mathematical formulas are given to describe the changes with depth of concentrations of chlorophylls b, c, and photosynthetic and photoprotecting carotenoids in Baltic phytoplankton resulting from the adaptation of algal cells to ambient conditions. They take into account the spectral variability and differences in intensity, characteristic of the Baltic, in the irradiance penetrating the water, and also the spectral similarities among the spectra of different groups of phytoplankton pigments. The formulas were derived and validated on the basis of an extensive set of empirical data acquired from different parts of the Baltic Sea in 1999-2016. The standard error factor x of these formulas ranges from 1.32 to 1.73. These values are lower than those obtained for formulas derived for ocean waters, in which the influence of allogenic constituents on optical properties is negligibly small: 1.44 and 1.52 respectively in the case of chlorophyll c, and 1.32 and 1.47 respectively for photoprotecting carotenoids. With these formulas, overall levels of the main groups of pigments can be calculated from known irradiance conditions and chlorophyll a concentrations at any depth in a layer equal to one and a half thicknesses of the euphotic layer (i.e. to an optical depth of τ = 7) in theBaltic.The accuracy of these approximations is close to that of estimates of other bio-optical characteristics in this sea. This was confirmed by a validation based on an independent dataset (x from 1.27 to 1.84).

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Size-selective microzooplankton grazing on the phytoplankton in the Curonian Lagoon (SE Baltic Sea)

Grinienė E., Šulčius S., Kuosa H.

Oceanologia

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2016

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No. 58 (4)

292--301

EN

Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates at two sites: freshwater (Nida) and brackish water (Smiltyne) in the Curonian Lagoon (SE Baltic Sea). Using the size-fractionation approach and dilution experiments, we found that the microzooplankton community was able to remove up to 78% of nanophytoplankton (2–20 μm) standing stock and 130% of the total daily primary production in the brackish waters of the lagoon, and up to 83% of standing stock and 76% of the primary production of picophytoplankton (0.2–2 μm) in the freshwater part. The observed differences were attributed to the changes in ciliate community size and trophic structure, with larger nano-filterers (30–60 μm) dominating the brackish water assemblages and pico-nano filterers (<20 μm and 20–30 μm) prevailing in the freshwater part of the lagoon.

3

Spectra of light absorption by phytoplankton pigments in the Baltic; conclusions to be drawn from a Gaussian analysis of empirical data

Ficek D., Kaczmarek S., Stoń-Egiert J., Woźniak B., Majchrowski R., Dera J.

Oceanologia

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2004

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No. 46 (4)

533-555

EN

Analysed by differential spectroscopy, 1208 empirical spectra of light absorption apl(?) by Baltic phytoplankton were spectrally decomposed into 26 elementary Gaussian component bands. At the same time the composition and concentrations of each of the 5 main groups of pigments (chlorophylls a, chlorophylls b, chlorophylls c, photosynthetic carotenoids and photoprotecting carotenoids) were analysed in 782 samples by HPLC. Inspection of the correlations between the intensities of the 26 elementary absorption bands and the concentrations of the pigment groups resulted in given elementary bands being attributed to particular pigment groups and the spectra of the mass-specific absorption coefficients established for these pigment groups. Moreover, balancing the absorption effects due to these 5 pigment groups against the overall absorption spectra of phytoplankton suggested the presence of a sixth group of pigments, as yet unidentified (UP), undetected by HPLC. A preliminary mathematical description of the spectral absorption properties of these UP was established. Like some forms of phycobilins, these pigments are strong absorbers in the 450-650 nm spectral region. The packaging effect of pigments in Baltic phytoplankton was analysed statistically, then correlated with the concentration of chlorophyll a in Baltic water. As a result, a Baltic version of the algorithm of light absorption by phytoplankton could be developed. This algorithm can be applied to estimate overall phytoplankton absorption spectra and their components due to the various groups of pigments from a knowledge of their concentrations in Baltic water.

4

Influence of photo- and chromatic acclimation on pigment composition in the sea

Majchrowski R., Ostrowska M.

Oceanologia

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2000

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No. 42 (2)

157-175

EN

The aim of this work was to find statistical relationships between the concentrations of accessory pigments in natural populations of marine phytoplankton and the absolute levels and spectral distributions of underwater irradiance. To this end, empirical data sets from some 600 stations in different parts of the seas and oceans were analysed. These data were obtained from the authors' own research and from the Internet's bio-optical data base. They included the vertical distributions of the concentrations of various pigments (identified chromatographically) and the vertical and spectral distributions of the underwater irradiance measured in situ or determined indirectly from bio-optical models. The analysis covered a total of some 4000 points illustrating the dependence of pigment concentration on underwater irradiance characteristics, corresponding to different depths in the sea. The analysis showed that the factor governing the occurrence of photoprotecting carotenoids (PPC) is short-wave radiation λ< 480 nm. A mathematical relationship was established between the relative PPC concentration (relative with respect to the chlorophyll a concentration) and the magnitude of the absorbed radiative energy per unit mass of chlorophyll a from the spectral interval λ< 480 nm, averaged in the water layers c z = 60 m (or less near the surface) to account for vertical mixing. This absorbed short-wave radiation ( λ< 480 nm) was given the name of Potentially Destructive Radiation (PDR*(z)). Analysis of the relationships between the concentrations of particular photosynthetic pigments (PSP), i.e. chlorophyll b, chlorophyll c, photosynthetic carotenoids (PSC), and the underwater irradiance characteristics indicated that these concentrations were only slightly dependent on the absolute level of irradiance E0(λ), but that they depended strongly on the relative spectral distribution of this irradiance f(λ)= E0(λ)/PAR0. The relevant approximate statistical relationships between the relative concentrations of particular PSP and the function of spectral fitting Fj, averaged in the layer Δz, were derived. Certain statistical relationships between the pigment composition of the phytoplankton and the irradiance field characteristics are due to the photo- and chromatic acclimation of natural populations of marine phytoplankton. These relationships can be applied in models of the coefficients of light absorption by phytoplankton.