Influence of underwater light fields on pigment characteristics in the Baltic Sea – results of statistical analysis**This work was carried out within the framework of the SatBałtyk project funded by the European Union through the European Regional Development Fund, (contract No. POIG.01.01.02-22-011/09 entitled ‘The Satellite Monitoring of the Baltic Sea Environment’), research project NN 304 275235 and also as part of IO PAS’s statutory research.

AbstractChanges in phytoplankton pigment concentrations in Case 2 waters (such as those of the Baltic Sea) were analysed in relation to the light intensity and its spectral distribution in the water. The analyses were based on sets of empirical measurements containing two types of data: chlorophyll and carotenoid concentrations obtained by HPLC, and the distribution of underwater light fields measured with a MER 2040 spectrophotometer – collected during 27 research cruises on r/v ‘Oceania’ in 1999–2004. Statistical analysis yielded relationships between the total relative (to chlorophyll a concentrations) concentrations of major groups of phytoplankton pigments and optical depth τ, between the total relative concentrations of major groups of photosynthetic pigments (chlorophylls b (Cchl b tot/Cchl a tot), chlorophylls c (Cchl c tot/Cchl a tot) and photosynthetic carotenoids (CPSC tot/Cchl a tot)) and the spectral fitting function (the ‘chromatic acclimation factor’), and between the total relative concentrations of photoprotective carotenoids (CPPC tot/Cchl a tot) in Baltic waters and the potentially destructive radiation (PDR), defined as the absolute amount of energy in the blue part of the spectrum (400–480nm) absorbed by unit mass of chlorophyll a. The best approximations were obtained for the total chlorophyll c content, while the relative estimation errors were the smallest (σ−=34.6%) for the approximation to optical depth and spectral fitting function. The largest errors related to the approximation of chlorophyll b concentrations: σ−=56.7% with respect to optical depth and 57.3% to the spectral fitting function.A comparative analysis of the relative (to chlorophyll a content) concentrations of the main groups of pigments and the corresponding irradiance characteristics in ocean (Case 1) waters and Baltic waters (Case 2 waters) was also carried out. The distribution of Cchl b tot/Cchl a tot ratios with respect to optical depth reveals a decreasing trend with increasing τ for Baltic data, which is characteristic of photoprotective pigments and the reverse of the trend in oceans. In the case of the Cchl c tot approximations, the logarithmic statistical error is lower for Baltic waters than for Case 1 waters: σ−=34.6% for Baltic data and σ−=39.4% for ocean data. In relation to photoprotective carotenoids (CPPC), σ− takes a value of 38.4% for Baltic waters and 36.1% for ocean waters. The relative errors of the approximated concentrations of different pigment groups are larger than those obtained for ocean waters. The only exception is chlorophyll c, for which the logarithmic statistical error is about 8.8% lower (σ−=34.6% for Baltic waters and 38.2% for ocean waters). Analysis of the errors resulting from the approximations of the photoprotective carotenoid content, depending on the energy characteristics of the underwater irradiance in the short-range part of PAR, showed that the relative errors are 1.3 times higher for Baltic waters than for ocean waters: σ−=38.4% for Baltic waters and 32.0% for ocean waters

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

Summary: 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 the Baltic. 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). Keywords: Phytoplankton pigments, Marine photosynthesis, Balti

Influence of underwater light fields on pigment characteristics in the Baltic Sea - results of statistical analysis

Changes in phytoplankton pigment concentrations in case 2 waters (such as those of the Baltic Sea) were analysed in relation to the lightintensity and its spectral distribution in the water. The analyses were based on sets of empirical measurements containing two typesof data: chlorophyll and carotenoid concentrations obtained by HPLC, and the distribution of underwater light fields measured with a MER2049 spectrophotometer - collected during 27 research cruises on r/v "Oceania" in 1999-2004. Statistical analysis yielded relationshipsbetween the total relative (to chlorophyll a concentrations) concentrations of major groups of phytoplankton pigments andoptical depth τ, between the total relative concentrations of major groups of photosynthetic pigments (chlorophylls b (Cchl b tot / Cchl a tot), chlorophylls c (Cchl c tot / Cchl a tot)and photosynthetic carotenoids (CPSC tot / Cchl a tot)) and the spectral fitting function (the "chromatic acclimation factor"),and between the total relative concentrations of photoprotective carotenoids (CPPC tot / Cchl a tot) in Baltic waters and the potentially destructive radiation (PDR), defined as the absolute amount of energy in the blue part of the spectrum (400-480 nm) absorbed by unit mass ofchlorophyll a. The best approximations were obtained for the total chlorophyll c content, while the relative estimation errors were thesmallest (σ_ = 34.6%) for the approximation to optical depth and spectral fitting function. The largest errors related to the approximation ofchlorophyll b concentrations: σ_ = 56.7% with respect to optical depth and 57.3% to the spectral fitting function).      A comparative analysis of the relative (to chlorophyll a content) concentrations of the main groups of pigments and the corresponding irradiance characteristics in ocean (case 1) waters and Baltic waters (case 2 waters) was also carried out. The distribution of Cchl b tot / Cchl a tot ratios with respect to optical depth reveals a decreasing trend with increasing τ for Baltic data, which is characteristic of photoprotective pigments and the reverse of the trend in oceans. In the case of the Cchl c tot approximations, the logarithmic statistical error is lower for Baltic waters than for case 1waters: σ_ = 34.6% for Baltic data and σ_ = 39.4% for ocean data. In relation to photoprotective carotenoids (CPPC), σ_ takes a value of 38.4% forBaltic waters and 36.1% for ocean waters. The relative errors of the approximated concentrations of different pigment groups are larger than those obtainedfor ocean waters. The only exception is chlorophyll c, for which the logarithmic statistical error is about 8.8% lower (σ_ = 34.6% for Baltic waters and 38.2% for ocean waters). Analysis of the errors resulting from the approximations of the photoprotective carotenoid content, depending on the energy characteristicsof the underwater irradiance in the short-range part of PAR, showed that the relative errors are 1.3 times higher for Baltic waters than for ocean waters: σ_ = 38.4%for Baltic waters and 32.0% for ocean waters

In a comfort zone and beyond—Ecological plasticity of key marine mediators

Copepods of the genus Calanus are the key components of zooplankton. Understanding their response to a changing climate is crucial to predict the functioning of future warmer high‐latitude ecosystems. Although specific Calanus species are morphologically very similar, they have different life strategies and roles in ecosystems. In this study, C. finmarchicus and C. glacialis were thoroughly studied with regard to their plasticity in morphology and ecology both in their preferred original water mass (Atlantic vs. Arctic side of the Polar Front) and in suboptimal conditions (due to, e.g., temperature, turbidity, and competition in Hornsund fjord). Our observations show that “at the same place and time,” both species can reach different sizes, take on different pigmentation, be in different states of population development, utilize different reproductive versus lipid accumulation strategies, and thrive on different foods. Size was proven to be a very mutable morphological trait, especially with regard to reduced length of C. glacialis. Both species exhibited pronounced red pigmentation when inhabiting their preferred water mass. In other domains, C. finmarchicus individuals tended to be paler than C. glacialis individuals. Gonad maturation and population development indicated mixed reproductive strategies, although a surprisingly similar population age structure of the two co‐occurring species in the fjord was observed. Lipid accumulation was high and not species‐specific, and its variability was due to diet differences of the populations. According to the stable isotope composition, both species had a more herbivorous diatom‐based diet in their original water masses. While the diet of C. glacialis was rather consistent among the domains studied, C. finmarchicus exhibited much higher variability in its feeding history (based on lipid composition). Our results show that the plasticity of both Calanus species is indeed impressive and may be regulated differently, depending on whether they live in their “comfort zone” or beyond it

SatBałtyk - A Baltic environmental satellite remote sensing system - an ongoing project in Poland. Part 1: Assumptions, scope and operating range

This paper is the second part of the description of the first stage of the SatBałtyk project's implementation. Part 1 (Woźniak et al. 2011, in this issue) presents the assumptions and objectives of SatBałtyk and describes the most important stages in the history of our research, which is the foundation of this project. It also discusses the operation and general structure of the SatBałtyk system. Part 2 addresses various aspects of the practical applicability of the SatBałtyk Operational System to Baltic ecosystem monitoring. Examples are given of the Baltic's characteristics estimated using the preliminary versions of the algorithms in this Operational System. At the current stage of research, these algorithms apply mainly to the characteristics of the solar energy influx and the distribution of this energy among the various processes taking place in the atmosphere-sea system, and also to the radiation balance of the sea surface, the irradiance conditions for photosynthesis and the condition of plant communities in the water, sea surface temperature distributions and some other marine phenomena correlated with this temperature. Monitoring results obtained with these preliminary algorithms are exemplified in the form of distribution maps of selected abiotic parameters of the Baltic, as well as structural and functional characteristics of this ecosystem governed by these parameters in the Baltic's many basins. The maps cover practically the whole area of the Baltic Sea. Also given are results of preliminary inspections of the accuracy of the magnitudes shown on the maps. In actual fact, the errors of these estimates are relatively small. The further practical application of this set of algorithms (to be gradually made more specific) is therefore entirely justified as the basis of the SatBałtyk system for the effective operational monitoring of the state and functioning of Baltic ecosystems. This article also outlines the plans for extending SatBałtyk to include the recording of the effects and hazards caused by current and expected storm events in the Polish coastal zone.pects of its practical applicability in the satellite monitoring of the Baltic ecosystem (see Woźniak et al. (2011) in this issue)