Physical Oceanography, Vol. 19, No. 6, 2009
MODELING OF DECADAL VARIATIONS IN THE BLACK-SEA ECOSYSTEM
V. L. Dorofeev
We consider the decadal evolution of the Black-Sea ecosystem on the basis of a three-dimen-
sional coupled model consisting of the Black-Sea circulation model and a biogeochemical block.
The circulation model is based on the widely used POM (Princeton Ocean Model) model. The
calculated hydrophysical fields are interpolated then to levels of the biogeochemical model,
which covers the upper 150-m layer. We demonstrate the close relationship between the interan-
nual variation of hydrophysical fields and the evolution of the main elements of the ecosystem.
The period under consideration (1992–2001) is characterized by the warming of the Black-Sea
upper layer, which can be traced by the trend of a growing surface temperature. It follows from
the results of modeling that the process of warming is also revealed in the subsurface hydrophys-
ical characteristics and the dynamics of the main elements of the Black-Sea ecosystem.
The Black-Sea ecosystem has been significantly transformed for the last 30–40 years. After the relatively
healthy state in the 1960s, it has been subject to extensive eutrophication with sharp decrease in the biological
diversity and fish resources in the subsequent years. The crisis of the Black-Sea ecosystem was a direct conse-
quence of climatic changes and external anthropogenic influence. Therefore, the modeling of the long-term evo-
lution of the ecosystem and the clarification of mechanisms that control this evolution are urgent problems. The
recovery of the Black-Sea ecosystem observed in the first half of the 1990s is explained by protecting measures
undertaken in order to control the anthropogenic contamination and excessive fishery. At the same time, based
on the data of Turkish anchory catch  and on analogous data for the Russian, Ukrainian, and Georgian sectors
of the Black Sea , one can conclude about the systematic trend toward decrease after 1995. It was shown in
 that an analogous unfavorable situation was observed in the second half of the 1990s at all levels of the nutri-
ent chain of the Black Sea from phytoplankton to fish. It was also marked there that these changes can be a re-
sult of changes in the physical state of the Black Sea caused by climatic factors, namely, by warming observed in
the Black Sea after 1993.
In the present work, we analyze the decadal evolution of the Black-Sea ecosystem and its relationship with
the evolution of hydrophysical fields. The analysis is carried out on the basis of the results of numerical model-
ing performed within a three-dimensional coupled model of the Black Sea.
Description of the Model
The three-dimensional model of the Black-Sea ecosystem is a coupled model that combines the model of
Black-Sea circulation and the biogeochemical part used for the investigation of interaction of various compo-
nents of the ecosystem.
This model of the ecosystem mainly coincides with the one presented in  but has some distinctive fea-
tures. The circulation and thermodynamics are calculated on the basis of the numerical POM model modified for
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
71–81, November–December, 2009. Original article submitted August
14, 2008; revision submitted September 15, 2008.
400 0928-5105/09/1906–0400 © 2009 Springer Science+Business Media, Inc.