10.1 Introduction
The study of the Black Sea neritic ecosystem is of great theoretical and practical
significance owing to the anthropogenic load on its coastal areas. The intensity of
such a load is largely conditioned by the variability of hydrochemical, hydrobiological and climatic conditions in these areas of the sea. Consequently, studying the
spatial-temporal variability of the nutrient and the suspended organic matter content distributions, which can indicate variability of the ecological condition of the
sea coastal areas, becomes more relevant.
Hydrochemical and hydrobiological conditions in the coastal areas of the western Black Sea significantly changed in 1960–1980 (Aubrey et al. 1996; Bologa
1977, 1978, 1985, 1992; Cociasu et al. 1996; Gevorgiz et al. 2005; Rozhdestwensky
1979, 1985, 1990, 1998; Zaitsev 1992; Zaitsev and Aleksandrov 1997). The reason
consisted in a sharp increase of the nutrients’ content in the waters of large rivers
(the Danube, the Dniester, the Dnieper and the Southern Bug) flowing into the
northwestern Black Sea (NWBS). Thus, the concentration of these elements on the
Danube shelf increased by 3–5 times (Garkavay et al. 2006; Yunev et al. 2007) as
compared to the 1950s that resulted in intensive development of phytoplankton
(“bloom” of water) and suffocation phenomena. Until 1970, in the Romanian and
the Bulgarian shelf sectors, the phytoplankton bloom was rare (Bodeanu 1992;
Bodeanu et al. 1998). However, already in the 1980s almost 50 cases of this
phenomenon were noted.
Study of the suspended organic matter (SOM) composition, an important biogeochemical element of the Black Sea ecosystem, as well as the variability of its
components (suspended organic carbon and nitrogen) permits to assess the marine
ecosystem productivity, the intensity of biochemical processes, and flexibility of
this ecosystem to the impact of various natural and anthropogenic factors. Such
research is of particular importance in NWBS, which is a significant area for
recreation, fishery and fish farms. NWBS differs from other sea areas by high
anthropogenic load including pollution by the coastal discharge (riverine, industrial
and domestic waste water, runoff of fertilizers, etc.), intensive navigation, oil and
gas exploration, and seabed mining, etc. The nutrients flowing into the sea with the
river discharges and their fast turnover provide favorable conditions for high
biological productivity in the region affected by the rivers. The productive and
destructive processes taking place in this region result in the fact that large amounts
of SOM are constantly involved and present in the biogeochemical cycle followed
by the subsequent sedimentation.
Based on the long-term (1979–1995) observations, the main features of the
spatial-temporal variability of the distribution of the SOM components’ content
in the surface and photosynthesis layers in the NWBS four areas (the northern,
western, central and eastern ones) differing in the degree of the effect of the riverine
discharge and open sea water masses, and on the Bulgarian shelf (Vostokov 1987,
1996) were considered in the papers (Burlakova et al. 1988, 1997; Kukushkin et al.
2004, 2006, 2008). It was revealed that the variability of the distribution of the
154
A.S. Kukushkin
The study of the Black Sea neritic ecosystem is of great theoretical and practical
significance owing to the anthropogenic load on its coastal areas. The intensity of
such a load is largely conditioned by the variability of hydrochemical, hydrobiological and climatic conditions in these areas of the sea. Consequently, studying the
spatial-temporal variability of the nutrient and the suspended organic matter content distributions, which can indicate variability of the ecological condition of the
sea coastal areas, becomes more relevant.
Hydrochemical and hydrobiological conditions in the coastal areas of the western Black Sea significantly changed in 1960–1980 (Aubrey et al. 1996; Bologa
1977, 1978, 1985, 1992; Cociasu et al. 1996; Gevorgiz et al. 2005; Rozhdestwensky
1979, 1985, 1990, 1998; Zaitsev 1992; Zaitsev and Aleksandrov 1997). The reason
consisted in a sharp increase of the nutrients’ content in the waters of large rivers
(the Danube, the Dniester, the Dnieper and the Southern Bug) flowing into the
northwestern Black Sea (NWBS). Thus, the concentration of these elements on the
Danube shelf increased by 3–5 times (Garkavay et al. 2006; Yunev et al. 2007) as
compared to the 1950s that resulted in intensive development of phytoplankton
(“bloom” of water) and suffocation phenomena. Until 1970, in the Romanian and
the Bulgarian shelf sectors, the phytoplankton bloom was rare (Bodeanu 1992;
Bodeanu et al. 1998). However, already in the 1980s almost 50 cases of this
phenomenon were noted.
Study of the suspended organic matter (SOM) composition, an important biogeochemical element of the Black Sea ecosystem, as well as the variability of its
components (suspended organic carbon and nitrogen) permits to assess the marine
ecosystem productivity, the intensity of biochemical processes, and flexibility of
this ecosystem to the impact of various natural and anthropogenic factors. Such
research is of particular importance in NWBS, which is a significant area for
recreation, fishery and fish farms. NWBS differs from other sea areas by high
anthropogenic load including pollution by the coastal discharge (riverine, industrial
and domestic waste water, runoff of fertilizers, etc.), intensive navigation, oil and
gas exploration, and seabed mining, etc. The nutrients flowing into the sea with the
river discharges and their fast turnover provide favorable conditions for high
biological productivity in the region affected by the rivers. The productive and
destructive processes taking place in this region result in the fact that large amounts
of SOM are constantly involved and present in the biogeochemical cycle followed
by the subsequent sedimentation.
Based on the long-term (1979–1995) observations, the main features of the
spatial-temporal variability of the distribution of the SOM components’ content
in the surface and photosynthesis layers in the NWBS four areas (the northern,
western, central and eastern ones) differing in the degree of the effect of the riverine
discharge and open sea water masses, and on the Bulgarian shelf (Vostokov 1987,
1996) were considered in the papers (Burlakova et al. 1988, 1997; Kukushkin et al.
2004, 2006, 2008). It was revealed that the variability of the distribution of the
154
A.S. Kukushkin