L. A. Shchur

The Effect of Mineral Particulate Matter on the Productive Characteristics of Bacterioplankton and the Degradation of Labile Organic Material

The effect of mineral particulate matter on the population of bacterioplankton, its aggregation, and productive characteristics was studied in model experiments with different concentrations of particulate kaolin and the same concentration of organic substance (sodium humate). It was found that the presence of mineral particulate matter stimulated the aggregation of bacterioplankton, improved bacterial production, and extended the productive period of bacterioplankton. The integral specific production of aggregated bacterioplankton was higher than that of free-swimming bacterioplankton. The energy metabolic coefficient K2 of bacterioplankton in the presence of mineral particulate matter was higher than in its absence.

The Role of Specific Cell Surface in Phytoplankton Productivity

It should be noted that the optical properties of suspensions are significantly determined by specific surface area. If several suspensions have equal specific surface areas and equal volumes (i.e., equal S / V values), their optical absorptions are also equal to each other. Because, under otherwise identical conditions, a fine-dispersion suspension has a larger surface area than a large-sized suspension of equal volume, the former absorbs light more effectively than the latter. Obviously, this is of particular importance in the case of photosynthesizing cells [10]. The goal of this work was to find an empirical correlation of the phytoplankton community’s production characteristics with the algal biomass boundary surface area. To attain this goal, the species composition, cell count ( N ), biomass ( B ), and cell size of each species of phytoplankton were determined in the Yenisei River and Lake Khanka. Conventional algological methods were used. The primary production ( P ) of the algal community was measured using the light-and-dark bottle oxygen method. The results of the study showed that both in Lake Khanka and in the Yenisei River, an increase in the S / V ratio was accompanied by a statistically significant increase in the specific production of photosynthesis (gross production per biomass unit) or assimilation index ( K as , day —1 ) calculated per carbon. The respective

Effect of suspended mineral matter on production characteristics of bacterio- and phytoplankton

The effect was determined of organo-mineral detritus (OMD), one of the components of suspended mineral matter in aquatic ecosystems, on the production characteristics of bacterioplankton (bacterial production Pb and destruction of organic matter Rb, as well as bacterial growth efficiency BGE). The relation was determined between these parameters and the ratio of the content of suspended mineral matter M to the total organic carbon content (M/TOC). More active utilization of organic matter by bacterioplankton in the presence of OMD resulted in its positive effect on specific production characteristics of the phytoplankton.

Relationships between the biomass and production of bacterio- and phytoplanktonic communities

Quantitative ratios of the biomasses of bacterio- and phytoplankton, interrelation of their production characteristics, and association of the functional characteristics with environmental factors were studied for Lake Khanka, the Yenisei River, and the Krasnoyarsk Reservoir. The ratio between the biomasses of bacterioplankton (Bb) and phytoplankton (Bp) in these water bodies was shown to vary within the range exceeding three orders of magnitude. Bacterioplankton biomass was relatively stable and varied from sample to sample by an order of magnitude. In more than 50% of the samples (total sample number, 495), bacterioplankton biomass exceeded that of the phytoplankton. The average Bb/Bp ratios for Lake Khanka, Yenisei River, and Krasnoyarsk Reservoir were 5.1, 2, and 1.4, respectively. Increased Bb/Bp ratios were found to correlate with elevated specific (per unit biomass) phytoplankton production. This finding indicated additional supply of biogenic elements to phytoplankton due to their recycling by bacterial communities. The ratio between bacterioplankton and phytoplankton production for Lake Khanka varied from year to year (0.07 to 0.76). For the Yenisei River and the Krasnoyarsk Reservoir these ratios were on average 0.19 and 0.27, respectively. According to the literature data for other water bodies, bacterial production may reach from 10 to over 100% of the primary production. The equilibrium density of bacterioplankton (maximal density of the population) in Lake Khanka was ~1.5 times higher than in the Yenisei River and the Krasnoyarsk Reservoir due to higher content of suspended mineral matter and associated organo-mineral detritus in the lake. The interaction between dissolved organic compounds sorbed on the surface of mineral particles results in chemical alteration of biochemically stable substrate into compounds which may be assimilated by aquatic microorganisms.

Functional characteristics of bacterioplankton with reference to its aggregation in water bodies of different types

The functional characteristics of bacterioplankton have been studied with reference to its aggregation in water bodies of different types. Several methods were used for calculation of the total numbers of bacteria and proportion of aggregated cells. Analysis of the experimental data has shown a relationship between the functional characteristics of bacterioplankton, such as bacterial production, destruction of organic matter, and energy coefficient, and the proportion of aggregated bacteria. It has been shown that as this proportion increases, the production per cell and energy coefficients also increase.

Effect of Preliminary Filtration on the Functional Characteristics of Bacterioplankton from Lake Khanka

The dependence of the functional characteristics of bacterioplankton from the loess of Lake Khanka on the pore size of filtering materials was investigated. Soluble organic matter (SOM), bacteria, and bacterial consumers adsorbed on particles suspended in the lake water were found to filter differently depending on the pore size of the filtering material. Filters with pore size 4.5 μm (filters II) retained up to 20% of SOM and 20–30% of bacterial cells. Filters III with pore size 2.87 μm retained almost 50% of SOM and about 40% of bacteria. The double layer of gauze no. 72 (referred to as filter I) with pores size 40 μm was unable to completely retain bacterial consumers. In the case of filtrates I and II, the generation time of bacterioplankton decreased with its increasing average daily concentration. In the case of filtrate III, the generation time of bacterioplankton was minimum and did not depend on its concentration. Oxygen consumption rates per one bacterial cell and per unit biomass in filtrates increased with decreasing pore size of the filters through which they had passed. The bacterial biomass and oxygen consumption rate increased exponentially in filtrates III and logarithmically in filtrates I.

Investigation of Bacterioplankton in the Loess-containing Lake Khanka

Some characteristics of bacterioplankton—generation time, daily (P) and specific (P/B) bacterioplankton production, and bacterial metabolic coefficientK2—in the loess-containing Lake Khanka were determined using five modifications of the bacterial-count procedure with the fluorescent dyes fluorescamin and erythrosin. Experiments showed that the organomineral complex (OMC) in this lake is broken down by chemoorganoheterotrophic bacteria. The increase in the loess content of the lake water intensified bacterial growth and the cycles of potassium, silicon, and other biogenic elements. The addition of starch to a loess suspension activated the breakdown of OMC due to the adsorption of starch on the OMC/water interface and stimulation of the metabolism of attached bacteria.