A STUDY OF PROPERTIES OF GENERALIZED MODEL FOR INTERANNUAL DYNAMICS OF EPIPHYTIC DIATOM COMMUNITIES

Abstract

Modeling the dynamics of the relative number of diatoms in epiphytic diatom communities of the macrophyte Ulva lactuca Linnaeus from three different coastal areas of Peter the Great Bay, Sea of Japan (Amur Bay, Ussuri Bay, and the Stark Strait), based on a tool of recurrent equations, makes it possible to identify the communities’ own natural dynamics in the water areas studied [Parensky, Levchenko, 2018]. It has been found that the reproductive capacity of the epiphytic diatom communities decreases in the following sequence: Amur Bay — Ussuri Bay — Stark Strait. As reported in literature, the nitrogen and phosphorus enrichment of the above-mentioned water areas decreases in the same sequence [Zvalinsky et al., 2013]. A relationship existing between the relative number of epiphytic diatoms and the level of trophicity of their habitat is assumed. Possible variants of relationships of the model coefficients with the trophicity level, including the necessary point (X = 0, Z = 0), are considered. Trophicity has proven to regulate all parameters of the multistep recurrent models describing the relative number of epiphytic diatoms. A generalized recurrent model for regulation of the relative number of epiphytic diatoms has been built; in this model, a regulating (trophic) factor is added to two limiting factors (photosynthetically active radiation and oxygen). A study of the model has shown that the trophicity level influences the interannual dynamics of the relative diatoms’ number and the duration of communities’ existence.