The Influence of Light, Temperature and Nutrient Deficiency on the Structural and Functional Characteristics of the Coccolithophorid Emiliania huxleyi (Prynnesiophyceae)

A clonal culture of the coccolithophore was isolated from the plankton of the Black Sea in February 2023. Its species identification was carried out using scanning electron microscopy and it was established that it belongs to type A. The optimal temperature for the development of this culture was revealed to be 20°C. The temperature coefficient (Q10) for the temperature range of 5–15°C was 3.36, and for the range of 10–20°C it was equal to 2.75. The influence of light on the structural and functional parameters of this species was studied. The maximum specific growth rate (1.37 day) was achieved at a light intensity of 157 μE/(m × s), and then it decreased as a result of light inhibition. The relative content of chlorophyll a per cell and dry weight decreased by 3–5 times as the light intensified from 8.5 to 425 μE/(m × s). The transfer of cells, which have the maximum intracellular pool of nutrients, into seawater depleted in nutrients, caused a decrease in the increase in their number and the efficiency of photosystem II, as well as an increase in cell volume and surface area. The sensitivity of photosystem II to phosphorus deficiency was higher than to nitrogen deficiency. Due to the intracellular pool of nutrients, this type of algae carried out 1.43–1.77 cell divisions.