Spatial-temporal variations in organic matter of the Sea of Azov

The spatial-temporal variations in the amount and biochemical composition of organic matter and the rates of its transformations in the ecosystems of the Russian part of the Sea of Azov are analyzed. Maximum OM concentrations are typical for Taganrog Bay. A characteristic feature of the Sea of Azov is a large proportion of particulate organic matter, which in summer in Taganrog Bay exceeded 35%. It is shown that not only the concentration of organic matter changes from season to season, but also its elementary (C_org, N_org, and P_org) and biochemical composition (proteins, carbohydrates, and lipids). The major biochemical compound of dissolved organic matter is shown to be carbohydrates (13–28%), and that of particulate matter is protein (44–51%). The hydrolytic (phosphatase and protease) and oxidation-reduction enzymes of electron-transport system demonstrate a high activity in summer. The estimated short turnover times of phosphates and protein suggest the rapid and complete utilization of organic matter in the Sea of Azov.     

Hydrochemical and Microbiological Features of Lake Mogil'noe

A comprehensive hydrochemical and microbiological study was conducted in Lake Mogil'noe. The vertical hysrochemical structure of the lake was analyzed. Large amounts of mineral compounds containing biogenic elements and their organic forms are shown to accumulate in the anaerobic zone of the lake. An abrupt increase in the concentration of C_org is recorded in the near-bottom layer, where it is almost an order of magnitude higher than that in the anaerobic zone of the Black Sea at a depth of 2000 m. All the processes are found to be most rapid in the boundary layer between the aerobic and anaerobic zones (8.25–9.25 m), where the primary production attains its maximum, the concentration of sulfates abruptly increases relative to the aerobic and anaerobic zones, microorganism population is maximum, as are the rates of sulfate reduction and glucose consumption by heterotrophic organisms.     

Organic matter of the Kiziltashskie Limans

Data on biochemical ecosystem monitoring of Kiziltashskie Limans are given. The limans are the only natural water bodies in the Russian Black Sea where pascual breeding of very valuable commercial fish is implemented. The presented concentrations of dissolved and particulate organic matter are 2–5 times greater than the values typical of the coastal zone of the Black Sea (from 7.9 to 27.7 mg/L and from 0.3 to 1.5 mg/L, respectively). The main biochemical component of the dissolved organic matter is carbohydrates, and that of particulate matter is protein. The share of particulate organic matter in the Kiziltashskie Limans never exceeds 7%. The elemental (C, N, P) and biochemical composition of organic matter is studied (carbohydrates, proteins, lipids). The rates of enzymatic reactions vary from season to season. Thus, processes of hydrolytic splitting of phosphor-organic compounds during primary production are very intensive in the spring, while processes of organic matter oxidation, catalyzed by enzymes of electron-transport system, are intensive in the summer.     

Hydrochemical Characteristics of Lake Kuril'skoe

Data of hydrochemical studies performed in September 2000 in Lake Kuril'skoe were used to establish the specific features of the spatial distribution of temperature, O₂, Si, mineral and organic forms of N and P, and to assess the availability of nutrients to phytoplankton. The concentrations of N_min and Si were found to be high throughout the water mass from the surface to the bed, whereas P_min concentration was low because of Fe abundance in the water. The development of phytoplankton is shown to be limited by the P_min deficiency, which is partially compensated by its regeneration and the capability of diatoms for heterotrophic nutrition.     

Results of Hydrochemical Studies of Lake Azabach'e (Kamchatka)

The nutrient basis of Lake Azabach'e is studied. The distribution of pH and the concentrations of O₂, P_min, Fe, N–NH⁺ ₄, N–NO^– ₃, Si, and organic forms of N and P are considered. The chemical basis of biological production of Lake Azabach'e is assessed. It is found that the amount of Si is excessive everywhere and that phytoplankton production is limited by phosphate and mineral nitrogen deficiency in virtually equal degrees.