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 self- purifying 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.