The model of areolae distribution and surface area of pores located on the valves of centric diatoms Coscinodiscus Ehr. and Thalassiosira Cl.

Chemical substances exchange between microalgae and environment occurs through the pores on the surface of its coat. Therefore, characteristics of substance flow are related to the total area of the pores of microalgae. Pores of centric diatoms are arranged in groups on the siliceous plates that cover the areolae of valves. The mathematical model that simulates the radial areolae arrangement on the valves of centric diatoms and on the basis of estimated number of areolae calculates the total area of the diatom pores is proposed. On the example of two diatom species Coscinodiscussp. and Thalassiosira eccentrica it was shown that their pores occupy 4-8% and 7-14% of total valve surface respectively. These values do not depend on the valve diameter and number of its areolae but are equivalent to the porosity of areolae of these species. It is supposed that about 10% of valve surface takes part in substance exchange and 100% of valve surface absorbs sunlight. Therefore substance flow through the valve is related to the energy flow (sunlight) as 1:10. It is suggested to use the ratio between total area of microalgae surface and area of its pores for the characteristics of microalgae productivity.