Simulation of Chemical and Biological Processes of Seagrass Growth
Purpose. The paper is purposed at developing a seagrass growth simulation model to describe qualitatively and quantitatively the chemical and biological processes of seagrass interaction with the environment. Methods and Results. The simulation model of the seagrass Zostera growth is represented as a dominant of seagrass phytocenoses in the Black Sea coastal areas. The model is based on the system of differential equations describing the processes of photosynthesis, uptake of nutrients (nitrogen and phosphorus) from the environment, production of organic matter, and release of oxygen and organic substances to the marine environment. The model control parameters are water temperature, intensity of photosynthetically active radiation, and concentrations of nitrates, ammonium and phosphates in the sea and pore waters. The model test calculations were carried out for the central part of the Donuzlav Bay that permitted to calculate the amounts of nitrogen and phosphorus uptake from the seawater and bottom, and those of oxygen, suspended and dissolved organic matter released to the environment from 1 sq. m area occupied by Zostera. In course of a year, from the 1 m depth, 1 kg of oxygen is released, 0.6 kg of carbon is produced, 64 g of nitrogen (47 g from water and 17 g from pore water) and 5 g of phosphorus are absorbed. Conclusions. The proposed model makes it possible to estimate the growth rate of seagrass, the amount of the nutrients uptake, the released oxygen, the produced and released organic matter, and the nitrogen and phosphorus concentrations in the plant tissues. The qualitative and quantitative assessments of the seagrass Zostera growth processes correspond to the field data represented in literature. It is shown that the developed model can be used as a block of an integrated ecological model, namely as a tool for quantitative assessing the intensity of chemical and biological processes in the coastal areas that are at risk of hypoxia.