Physical Oceanography, Vol. 19, No. 1, 2009
MATHEMATICAL MODELING OF MARINE SYSTEMS
COMPARATIVE ANALYSIS OF THE EXPERIMENTS AIMED AT MODELING
MARINE ECOSYSTEMS BY USING THE OBJECT-ORIENTED APPROACH
E. F. Vasechkina and V. D. Yarin
We describe the results of comparative analysis of the numerical experiments carried out by us-
ing two different approaches to modeling the biological components of marine ecosystems: “or-
dinary” and object-oriented. These results demonstrate that the character of the space distribu-
tion (patchiness) of the food resource on the lowest level of the trophic chain strongly affects the
growth rate of the density of population on the next level and forms specific features of its space
distribution which, in fact, affect the productivity of all levels of the trophic chain. The repre-
sentation of phytoplankton (lowest level) in the model in the form a continuous field of passive
admixtures creates more favorable conditions for the nutrition of the organisms consuming this
resource. Therefore, in our calculations based on the “ordinary” procedure of modeling of ma-
rine ecosystems, the productivity of all its living components is higher than in the case of appli-
cation of the object-oriented method. The indicated distinctions are especially well visible on the
scales of about ten kilometers.
The heterogeneity of the space distribution of plankton (also called patchiness) is observed on all space
scales from centimeters to tens of kilometers. The nature of this phenomenon, its statistical properties, and de-
pendence on the physical parameters of the medium are extensively studied by researchers in the fields of oce-
anography and ecology. The heterogeneity of the distribution of plankton as a food resource must affect the pro-
ductivity of higher levels of the trophic chain in the marine ecosystem. As one of the practical purposes of mo-
deling of marine ecosystems, one can mention the evaluation of current and future fish stocks. Hence, it seems
reasonable to analyze the correspondence between the statistical properties of the fields of biological components
of the ecosystem simulated by using the models and the characteristics of the observed fields.
The observed and simulated space distributions of phytoplankton and zooplankton on different scales are
analyzed in . The simulated fields are computed by using the “ordinary” and object-oriented approaches. As
shown in , the object-oriented approach enables one to simulate the space variations of the fields of plankton
more adequately than the ordinary procedure of modeling. According to the ordinary approach, the fields of bio-
logical elements are represented in the form of the arrays of values at the nodes of a regular grid, and the dynam-
ics of these fields is governed by the equations of evolution of the fields of passive admixtures. In the object-ori-
ented approach, the biological components of the ecosystem are described by numerous objects each of which
simulates the vital functions of a separate individual. In , one can find the results of numerical experiments
carried out by using a combined object-oriented model (OOM)  whose living components (phytoplankton,
zooplankton, protozoa, and bacterial plankton) are represented as great numbers of objects and nonliving compo-
nents (biogenic elements, hydrophysical characteristics, and oxygen) are specified, as usual, on the grid.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
26–35, January–February, 2009. Original article submitted August 17,
2007; revision submitted September 28, 2007.
22 0928-5105/09/1901–0022 © 2009 Springer Science+Business Media, Inc.