[Statistical methods for analysis of communities' species structure (with riverine macrozoobenthos as an example)].

Species turnover or coherence in species co-occurrence as well as boundary clumping and nestedness in structural composition of ecological communities reflect the extent of determinancy in their organization (Leibold, Mikkelson, 2002). These phenomena may be a consequence of either interactions between species or heterogeneity in spatial distribution of populations density. We have examined statistical patterns of species structure variability using benthic communities of riverine ecosystems as an example.

[Nonparametric methods for comparative assessment of species diversity as applied to riverine macrozoobenthic communities].

Models for relationship between sampling effort and estimates of species number and other characteristics of species diversity are considered and evaluated. In the analysis, different randomization algorithms and other statistical methods of monitoring data processing are used including jackknife and bootstrap procedures, algorithms ICE and Chao2, Colwell-Mao interpolation model, Mikhaelis-Menten curves, and others. A comparative analysis of overall species richness in macrozoobenthic communities using streams of the Lower Volga basin as a case study is performed with the aid of different extrapolation models, and the resulting estimates are discussed.