Light adsorption of phytoplankton and parameters of its biomass and cell biovolumes in the Black Sea in 1998-2000

Bio-optical characteristics of phytoplankton have been observed during two-year monitoring in the western Black Sea. High variability in light absorption coefficient of phytoplankton was due to change of pigment concentration and chlorophyll a specific absorption coefficient. A relationships between light absorption coefficients and chlorophyll a concentration have been found: for the blue maximum (a_ph(440) = 0.0413x**0.628; R**2 = 0.63) and for the red maximum (?_ph(678) = 0.0190x**0.843; R**2 = 0.83). Chlorophyll a specific absorption coefficients decreased while pigment concentration in the Sea increased. Observed variability in chlorophyll a specific absorption coefficient at chlorophyll a concentrations <1.0 mg/m**3 had seasonal features and was related with seasonal change of intracellular pigment concentration. Ratio between the blue and red maxima decreased with increasing chlorophyll a concentration (? = 2.14 x**-0.20; R**2 = 0.41). Variability of spectrally averaged absorption coefficient of phytoplankton (a'_ph ) on 95% depended on absorption coefficient at the blue maximum (y = 0.421x; R**2 = 0.95). Relation of a_ph with chlorophyll a concentration was described by a power function (y = 0.0173x**0.0709; R**2 = 0.65). Change of spectra shape was generally effected by seasonal dynamics of intracellular pigment concentration, and partly effected by taxonomic and cell-size structure of phytoplankton.

在黑海西部为期两年的监测中，研究人员观测了浮游植物的生物光学特性。浮游植物的光吸收系数存在高度变异性，这归因于色素浓度和叶绿素a比吸收系数的变化。研究发现光吸收系数与叶绿素a浓度之间存在如下关系：蓝色最大值处（a_ph(440) = 0.0413x**0.628；R² = 0.63）和红色最大值处（?_ph(678) = 0.0190x**0.843；R² = 0.83）。随着黑海色素浓度的增加，叶绿素a比吸收系数呈下降趋势。在叶绿素a浓度低于1.0 mg/m³时，观测到的叶绿素a比吸收系数变异性具有季节性特征，且与细胞内色素浓度的季节变化相关。蓝、红最大值的比值随叶绿素a浓度增加而降低（? = 2.14 x**-0.20；R² = 0.41）。浮游植物光谱平均吸收系数（a'_ph）的变异性中，95%可由蓝色最大值处的吸收系数解释（y = 0.421x；R² = 0.95）。光谱形状的变化主要受细胞内色素浓度的季节动态影响，部分受浮游植物的分类学和细胞大小结构影响。