Pigment concentrations and biomass of phytoplankton and of its dominant species in surface Black Sea waters in 1998-2000

Data on chlorophyll a concentration and species composition and biomass of phytoplankton have been collected for two years continues monitoring in the central part and the slope zone of the Black Sea. Seasonal dynamics of chlorophyll a concentration correspond to U-type. It is characterized by low values in summer, high values in autumn, which are going to winter-spring bloom of phytoplankton. Oscillations of mean values of chlorophyll concentrations are equal to 3-4 in the central part and 2 - in the slope zone. In the autumn-winter-spring period high values of phytoplankton biomass are related to typical blooming diatom algae in the first year and other taxons - in the second year. Relationship between relative content of phaeopigment and chlorophyll concentration has been determined for the central western part of the sea. Seasonal dynamics of carbon/chlorophyll a ratio has been shown. For both regions mean values of this ratio were equal to ~20 in autumn-winter-spring time and 40-50 - in summer time.

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.