Factors of Dynamics of Plankton Crustacean Communities under Eutrophic Conditions

Russian Journal of Ecology - It has been shown that the main drivers of the dynamics of cladoceran and copepod abundances can be predators (fish), the quantity and/or quality of food in terms of...     

Investigation of Boundary Layer Fine Structure in Arid Regions: Injection of Fine Dust into the Atmosphere

Fine structure of the atmospheric boundary layerin desert regions of Kalmykia and on dried bottom of theAral Sea and its relation to soil particle emission in theatmosphere are discussed. It was found that in a hot seasonin the absence of dust storms convective processes lift updust particles into the atmospheric boundary layer fromsandy landscapes of Kalmykia and Sub-Aral regions. Thisaerosol consists of aggregate particles and contains asignificant amount of long-living aerosol of size less than5 m (including fine-dispersion 0.01–0.1 maerosol). The increasing of fine aerosol concentration wasfound at air temperature above 25 °C, surfacetemperature above 50 °C, and relative humidityless than 40–50%. Some mechanisms influencing the particle emission rates are briefly considered.     

Dependence of demographic parameters and results of competition on temperature in cladocerans

Laboratory experiments and computer simulations have been performed to study the influence of increased temperatures on the structure of cladoceran communities. Analysis of changes in the rate of population growth and demographic parameters has shown that smaller cladoceran species are less sensitive to decreased concentrations of food at any of the test temperatures (18, 21, and 27°C). An increase in temperature from 18°C to 27°C has been shown to facilitate the establishment of acute competition conditions. At 18°C, periods of food deficiency are shorter, and competition is therefore less manifested than at 27°C. According to the results of computer simulations, alleviation of competition in waters with “low” temperatures results from reduction of the periods of food deficiency because of prolonged juvenile development.     

A new model for the CBL growth based on the turbulent kinetic energy equation

Starting from the evolution equation for the turbulent energy density spectrum (EDS), we develop a new model for the growth of the Convective boundary layer (CBL). We apply dimensional analysis to parameterize the unknown inertial transport and convective source term in the dynamic equation for the three-dimensional (3-D) spectrum and solve the 3-D EDS equation. The one-dimensional vertical spectrum is derived from the 3-D spectrum, employing a weight function. This allows us to select the magnitude of the vertical spectral component for the construction of the growing 3-D EDS. Furthermore, we employ the vertical component of the energy spectrum to calculate the eddy diffusivity (required in dispersion models). Currently there are no available experimental data to directly verify our EDS model.     

Experimental Study of Effects of Bivalve <Emphasis Type="Italic">Dreissena polymorpha</Emphasis> on Phytoplankton under Eutrophic Conditions

The bivalve Dreissena polymorpha (Pallas, 1771) was shown to significantly decrease the biomass of cyanoprokaryotes in water collected from Lake Mikolajskoe (Poland) including potentially toxic species Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju. However, the mollusks increased the biomass of large filaments of green algae which are of low nutritional quality for zooplankton.