Modeling of the Biochemical Processes in the Benthic Phytocenosis of the Coastal Zone

Abstract

A simulation model of bottom phytocenosis based on object-oriented approach to marine ecosystems was proposed. Data and methods. The dynamic model of macroalgae growth is based on the system of ordinary differential equations describing the processes of photosynthesis and production of organic matter, nitrogen and phosphorus uptake, and extraction of organic matter and oxygen into the environment. Photosynthetically active radiation (PAR), water temperature, a content of nutrients in the water were chosen as the control variables. Results. The model allows an estimation of nitrogen and phosphorus content in algae tissues, rate of photosynthesis, actual parameters of uptake nutrients and extraction of organic matter depending on the control variables. Analytical solutions for the steady state of a system at constant control variables were obtained. Parameterization of photosynthetic and kinetic parameters of seaweed using their dependencies of the specific surface of thalli was proposed. The growth of red macroalga Gracilaria biomass over a year was simulated with a preset dynamics of control variables (for the Southern Coast of Crimea). Yearly oxygen production, nitrogen and phosphorus uptake and accumulated quantity of these elements in algae tissues were calculated; the volume of organic matter coming to the next trophic level (benthic organisms and finfish) was estimated. The results correspond to the published observational ecosystem data in the region under study. Discussion and conclusion. The developed model will be used as a separate unit simulating the dynamics of bottom phytocenosis in a three-dimensional object-oriented physical-chemical-biological model of the marine ecosystem.

Object-Based Modeling of Marine Phytoplankton and Seaweeds

“…The dynamic models for the micro and macroalgae subclasses describing their evolution in the changing environment are the methods of the appropriate subclasses. These are individual-based models (IBMs) [18,19]. In comparison with the grid representation of biological components in the spatial ecological models, this approach provides the following advantages:…”

“…Objects of this class perform the array "Phytobenthos" (Figure 1). The main method of this class is the model describing physiology of the macrophytes [18]. The dynamical equations are similar to Equations (1)-(9) with the only difference in the description of the specific growth rate.…”

“…A detailed description of the chemical model and numeric values of the model parameters can be found in [25]. Here, we show the equations for dissolved oxygen in the upper and bottom layers as an example (Equations (18) and (19)).…”