Effect of Under-Ice Light Intensity and Convective Mixing on Chlorophyll a Distribution in a Small Mesotrophic Lake

Autor: N. I. Pal’shin, T. V. Efremova, Roman Zdorovennov, Galina Zdorovennova, A. Yu. Terzhevik, Galina Gavrilenko
Rok vydání: 2019
Předmět:
Zdroj: Water Resources. 46:384-394
ISSN: 1608-344X
0097-8078
DOI: 10.1134/s0097807819030175
Popis: Data of long-term measurements of under-ice solar radiation, water temperature, and chlorophyll a are analyzed in four phytoplankton groups (green, diatoms, blue-green, and cryptophyte algae) in a small mesotrophic Vendyurskoe Lake (Karelia) in the period of spring under-ice convection. It is shown that, after thawing away of snow cover from lake surface, under-ice illumination increases, water temperature rises, the depth of convectively mixed layer (CML) increases, and microalga photosynthesis intensifies. In the daytime, chlorophyll a extremums appear in the CML, and, unlike the homogeneous characteristics (water electric conductivity, mineralization, etc.), the cells of different phytoplankton species can be used as tracers in studying convective mixing. A prognostic equation is obtained, reflecting an inverse dependence of the coefficients of variation of chlorophyll a concentration in CML on solar radiation fluxes, penetrating under ice bottom surface. A direct relationship was shown to exist between the increase in chlorophyll concentration in CML and its thickness.
Databáze: OpenAIRE
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