Variability of light absorption by phytoplankton pigments, non-algal particles and colored dissolved organic matter of coastal and open waters of the Ukrainian part of the Black sea

Abstract

Variability of light absorption by phytoplankton pigments, non-algal particles and colored dissolved organic matter was analyzed by monthly bio-optical monitoring of coastal and deep waters near Sevastopol in 2009–2014 and by sampling in northwestern part of the Black Sea and along the Crimean coast in August 2011. Light absorption coefficients by phytoplankton were in 10 times bigger in coastal zone near Dnieper Delta compared with deep part of the sea in summer. In autumn light absorption coefficients by phytoplankton were in 5 times bigger in coastal zone near Dnieper Delta compared with deep part of the sea. Light absorption coefficients by non-algal particles in deep water and in coastal zone equally increased in summer and in autumn. Light absorption coefficients by colored dissolved organic matter were in 4 times bigger in coastal zone compared with deep part of the sea in summer. It was found that in summer, both in deep water and near the coast, the main contribution to the total light absorption was made by colored dissolved organic matter, smaller contribution was made by phytoplankton, the smallest contribution was made by non-algal particles. Seasonal and spatial variability of light absorption coefficients by phytoplankton, non-algal particles and colored dissolved organic matter was found. It is necessary to separate data from coastal and deep waters of the Black Sea, as well as to divide data by seasons to obtained better results when calculating primary production by using satellite data.