PHYTOPLANKTON PRIMARY PRODUCTIVITY

Abstract

Primary productivity is an important integral parameter describing energy potential of aquatic organisms’ vital activity. Primary productivity determines the quality of water environment, its selfpurifying capacity – from the Global Ocean to various continental ecosystems (Odum 1953, Williams et al. 2002, Bott et al. 2006, Kuehl and Troelstrup 2013). Primary productivity is a bioenergy process transforming the solar energy into the energy of chemical bonds in organic matter, newly synthesized by the autotrophic link. The autotrophic link is mainly formed by algae from different ecological groups (phytoplankton, phytobenthos, phytoperiphyton) and higher aquatic plants. As any process of energy production and transition, primary production in aquatic ecosystems is regulated by the laws of thermodynamics: the first law – the Lomonosov-Lavoisier law, the second law – the entropy law (Odum 1953). It is necessary to state clearly, that green plants do not transform the total amount of the Sun’s radiant energy, but only a part of it, within the spectral range between 480 and 720 nm (within the wavelength band of photosynthetically active radiation). A simplified equation describing the primary production process can be represented as follows: Proceeding from the above equation, primary productivity may be considered equivalent to (analogous to) the photosynthesis intensity. There is a range of various methods for estimating PP: according to algal cell number, according to nutrient dynamic in water, according to diurnal dynamics of dissolved oxygen, according to chlorophyll a content, light-and-dark bottle method in oxygen or radiocarbon modification. With consideration taken of these methods’ advantages and disadvantages, researchers will be able to obtain the most reliable and unbiased primary productivity data.