Abstract A number of methods for indirectly estimating the size structure of the phytoplankton population in the Baltic Sea were analysed. These analyses were based on ~1000 samples of phytoplankton pigment concentrations and light absorption coefficients taken from surface waters, mainly in the southern Baltic Sea. Standard reference methods of diagnostic pigment analysis (DPA), originally developed for open ocean conditions, were employed to determine the proportions of pico-, nano- and microplankton groups in the population. A new preliminary modification of DPA, better adapted to the specific nature of the phytoplankton population in the Baltic Sea, is also proposed. Specific relationships between diagnostic pigments and chlorophyll a concentration are taken into account. The accuracies of different methods potentially useful in remote sensing observations of the Baltic Sea were examined. Several standard methods based on the total abundance of phytoplankton known from the literature were compared with the two new proposed variants. One with the newly developed typical Baltic pattern of change, representing the average relationship between the chlorophyll a concentration and the percentage contributions of the various size groups, and the other based on spectral absorption properties. The comparison indicated that if the standard methods known from the literature were applied to Baltic data, the estimates would be encumbered with significant errors, both systematic (up to ±30%) and statistical (up to 24%). It was also shown that the systematic errors of such estimates could be substantially reduced by applying one of the two preliminary variants of the methods proposed here.

中文翻译：

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间接估计浮游植物种群规模结构的方法比较及其适应波罗的海特定条件的初步修改

摘要 分析了多种间接估算波罗的海浮游植物种群规模结构的方法。这些分析基于约 1000 个浮游植物色素浓度和来自地表水（主要在波罗的海南部）的光吸收系数的样本。最初为开阔海洋条件开发的诊断色素分析 (DPA) 的标准参考方法被用来确定种群中微型、纳米和微型浮游生物群的比例。还提出了一种新的 DPA 初步修改，以更好地适应波罗的海浮游植物种群的特定性质。考虑了诊断色素和叶绿素 a 浓度之间的特定关系。检查了在波罗的海遥感观测中可能有用的不同方法的准确性。将文献中已知的基于浮游植物总丰度的几种标准方法与两个新提出的变体进行了比较。一种具有新开发的典型波罗的海变化模式，代表叶绿素 a 浓度与各种尺寸组的百分比贡献之间的平均关系，另一种基于光谱吸收特性。比较表明，如果将文献中已知的标准方法应用于波罗的海数据，估计将受到严重误差的阻碍，包括系统性（高达 ±30%）和统计性（高达 24%）。