Seasonal variability of the vertical distribution of spectral bio-optical properties of the Black Sea coastal waters near Sevastopol
D.V. Kalmykova, T.Ya. Churilova, T.V. Efimova, N.A. Moiseeva, E.Yu. Skorokhod, E.A. Zemlianskaia
The A.O. Kovalevsky Institute of Biology of the Southern Seas, Sevastopol, Russia
Keywords: chlorophyll a, phytoplankton, non-algal particles, dissolved organic matter, light absorption, Black Sea
Abstract
Seasonal variability of the vertical distribution of chlorophyll a concentration, coefficients of spectral light absorption by optically active components of water and, spectral downwelling irradiance has been investigated in coastal waters of the Black Sea near Sevastopol in 2022-2023. Concentration of phlorophyll a in euphotic zone was minimal in winter (0.66 mg/m3) and maximal in spring (3.57 mg/m3). It has been revealed that colored dissolved organic matter was dominated in absorption at 438 nm in all the seasons. It was noted that the relative contribution of phytoplankton to the total non-water light absorption by all optically active components at 438 nm was the highest in summer. It has been shown that an increase in the total light absorption by suspended and dissolved organic matters led to a narrowing of the euphotic zone and a change in the spectral features of downwelling irradiance. Vertical distribution of Tchl- a and optically active components was associated with hydrophysical characteristics of waters.
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