Vertical distribution of chlorophyll “a” concentration in the Black Sea in summer and autumn periods according to the data of the probe CTD complex and direct measurements

I.M. Mansurova, L.V. Stelmakh, A.A. Farber

The A.O. Kovalevsky Institute of Biology of the Southern Seas of RAS,

RF, Sevastopol, Nakhimov Av., 2


DOI: 10.33075/2220-5861-2023-2-84-91

UDC 582.261.1(262.5)                                                                                          


   In this paper, a comparative assessment of the detection of chlorophyll “a” in the Black Sea phytoplankton was carried out according to the data obtained with the probe CTD complex and direct measurements during the temperature stratification of water column in the summer and autumn of 2022. In vivo fluorescence is often used as an express method for determining the chlorophyll “a” content in the Black Sea, which is identified using a submersible fluorescent probe directly during outboard operations. However, a number of studies indicate the low accuracy of such determinations due to the weak correlation between chlorophyll “a” and its fluorescence, which makes it impossible to use a constant coefficient linking these two parameters.

   We have considered the relationship between the concentration of chlorophyll “a” according to sounding data and direct measurements for different layers in the water column in shallow waters and areas with a total depth of more than 200 m. The closest relationship between the studied parameters was obtained for the upper mixed layer (UML) in deep waters in summer. In most cases this relationship was weak in the thermocline and below it in this area, as well as in all three layers in shallow waters. In autumn the results of determining the concentration of this pigment by the two methods do not coincide completely in the two upper layers where the most of phytoplankton is concentrated (UML and thermocline). At present, chlorophyll “a” concentration data obtained from in vivo fluorescence should only be used for a rough estimate of its vertical distribution in the sea.

Keywords: phytoplankton, chlorophyll a, fluorescence, Black Sea.

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