Impact of weather variability on spatial and seasonal dynamics of dissolved and suspended nutrients in water column of meromictic Lake Shira
The paper summarizes the author’s theoretical and experimental researches aimed at studying the rule of stable coexistence of interacting microbial populations within same trophic level. Populations of yeast and algae interact in open continuous cultures through regulating factors (RFs), which come together by the ability to be released or taken up by a microbial population and affect the growth of this and other population. Theoretical and experimental studies show that in steady state, the number of coexisting species is not greater than the number of RFs. Two-dimensional regions with different resultant species compositions of experimental equilibrium communities are plotted in the coordinates of “input levels of RFs”. This is perhaps the first study showing that the background steady-state levels of RFs in the system are not related to their input levels. This effect has been termed autostabilization of RFs, and its theoretical basis has been developed. A new criterion of intra- and inter-population microbial interactions has been introduced for RFs—growth acceleration response to a change in population density. Based on the proposed new criterion, experimental and theoretical estimates of the intensity and the sign of interactions between populations are given, allowing the quantification of their complex relationships, which was earlier unattainable. An integrated approach to detection of RFs has been proposed based on this criterion and the autostabilization effect.