The article presents the possible methods for determining biological or statistically significant differences between taxocenoses compared with respect to biodiversity. To obtain a complete description of biological differences between the compared hypothetical communities, the following indices were calculated: S (taxon richness), H (the Shannon index), Hmax (the maximum value of the Shannon index for the richness of taxa represented by the same number of individuals), Vd (a percentage value of covering the structural capacity of community, “evenness deficiency”), E (the MacArthur index - a taxon number (S) in a community for which the observed value of H equals Hmax), and Ps (a taxon richness shortage in percents). Moreover, a graphic profile method (Дд, Tj, and Lj profiles) was used for comparing the diversity of the communities. To obtain information about statistically significant differences in biodiversity between the analysed communities, rarefaction curves were applied. The curves are based on the null models and the Monte Carlo method. The rarefaction method resulted in determination of the statistical significance of the differences between taxon richness and Shannon's index values for the compared communities. The Vd and Ps indices and the profile method allowed concluding about the significance of the biological differences between taxocenoses, even when their values of Shannon's H indices were numerically similar.
 Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy.
 Andrzejewski R, Weigle A. Różnorodność biologiczna Polski (Biological diversity of Poland). Warszawa: Narodowy Fundusz Ochrony Środowiska; 2003.
 Curds CR. A theoretical study of factors influencing the microbial population dynamics of the activated sludge process - I The effects of diurnal variations of sewage and carnivorous ciliated protozoa. Water Res. 1973;7(9):1269-1284. DOI: 10.1016/0043-1354(73)90004-3.
 Al-Shahwani SM, Horan NJ. The use of protozoa to indicate changes in the performance of activated sludge plants. Water Res. 1991;25(6):633-638. DOI: 10.1016/0043-1354(91)90038-R.
 Forney LJ, Liu WT, Guckert JB, Kumagai Y, Namkung E, Nishihara T, et al. Structure of microbial communities in activated sludge: Potential implications for assessing the biodegradability of chemicals. Ecotoxicol Environ Safety. 2001;49(1):40-53. DOI: 10.1006/eesa.2001.2034.
 De Gregorio C, Caravelli AH, Zaritzky NE. Application of biological indices and a mathematical model for the detection of metal coagulant overload in a laboratory scale activated sludge reactor with phosphate simultaneous precipitation. Chem Eng J. 2011;172(1):52-60. DOI: 10.1016/j.cej.2011.05.063.
 Babko R, Łagód G, Jaromin-Gleń KM. Abundance and structure of ciliated protozoa community at the particular devices of “Hajdów” WWTP. Ann Set Environ Protect. 2012;14:56-68.
 O'Reilly N, Novotny V. Water quality, ecological and flood risks to receiving waters due to urban runoff and urbanization. Technical report No. 2. Institute for Urban Environmental Risk Management, Marquette University; 1999.
 The Federal Interagency Stream Restoration Working Group (FISRWG) Stream Corridor Restoration -Principles, Processes and Practices, by the Federal Interagency Stream Restoration Working Group, 1998.
 Ogbeibu AE, Orihabor BJ. Ecological impact of river impoundment using benthic macro-invertebrates as indicators. Water Res. 2002;36(10):2427-2436. DOI: 10.1016/S0043-1354(01)00489-4.
 Borchardt D, Richter S. Identification of significant pressures and impacts upon receiving waters. Water Sci Technol. 2003;48(10):33-38.
 Stastna G, Kabelkova I, Stransky D. Interaction of river dam and system sewer (in Czech). Stavebni obzor. 2008;17(1):16-20.
 Whitaker RH. Evolutional measurements of species diversity. Taxon. 1972;21(2/3):213-251.
 Shannon CE, Weaver W. The Mathematical Theory of Communication. University of Illinois Press, Urbana, Chicago, 1949, reprint 1998.
 Woodiwiss FS. The biological system of stream classification used by Trent River Board. Chem Industry. 1964;11:443-447.
 Washington HG. Diversity, biotic and similarity indices: a review with special relevance to aquatic ecosystems. Water Res. 1984;18(6):653-694. DOI: 10.1016/0043-1354(84)90164-7.
 Brower JE, Zar JH, Von Ende CN. Field and Laboratory Methods for General Ecology. New York: WCB McGraw-Hill 1998.
 Madoni P. A sludge biotic index (SBI) for evaluation of activated sludge plants based on the microfauna analysis. Water Res. 1994;28(1):67-75. DOI: 10.1016/0043-1354(94)90120-1.
 Knoben RAE, Roos C, van Oirschot MCM. Biological assessment methods for watercourses. UN/ECE Task Force on Monitoring & Assessment, Lelystad; 1995.
 Ravera O. A comparison between diversity, similarity and biotic indices applied to the macroinvertebrate community of a small stream: the Ravella river (Como Province, Northern Italy). Aquat Ecol. 2001;35:97-107.
 Gorzel M, Kornijów R. Biologiczne metody oceny jakości wód rzecznych. Kosmos. 2004;53(2):183-191.
 Kokes J, Zahradkova S, Nemejcova D, Hodovsky J, Jarkovsky J, Soldan T. The PERLA system in the Czech Republic: a multivariate approach for assessing the ecological status of running waters. Hydrobiologia. 2006;566(1):343-354. DOI: 10.1007/s10750-006-0085-4.
 Rożej A, Cydzik-Kwiatkowska A, Kowalska B, Kowalski D. Structure and microbial diversity of biofilms on different pipe materials of a model drinking water distribution systems. World J Microbiol Biotechnol. 2014:1-11. DOI: 10.1007/s11274-014-1761-6.
 Gotelli NJ, Entsminger GL. EcoSim: Null models software for ecology. Version 7.0, Jericho: Ackuiret Intelligence Inc. and Kesey-Bear, USA, 2006.
 Błędzki LA. Method for comparing species richness and species diversity (in Polish). Part I. Bioskop. 2007;1:18-22.
 Błędzki LA. Method for comparing species richness and species diversity (in Polish). Part II. Bioskop. 2007;2:20-23.
 Łagód G, Chomczyńska M, Montusiewicz A, Malicki J, Bieganowski A. Proposal of measurement and visualization methods for dominance structures in the saprobe communities. Ecol Chem Eng S. 2009;16(3):369-377.
 Colwell RK, Chao A, Gotelli NJ, Lin SY, Mao CX, Chazdon RL, et al. Models and estimators linking individual-based and sample-based rarefaction, extrapolation and comparison of assemblages. J Plant Ecol. 2012;5(1):3-21. DOI: 10.1093/jpe/rtr044.
 MacArthur RH. Patterns of species diversity. Biol Rev. 1965;40(4):510-533. DOI: 10.1111/j.1469-185X.1965.tb00815.x.
 Hulbert SH. The nonconcept of species diversity: a critique and alternative parameters. Ecology. 1971;52(4):577-586. DOI: 10.2307/1934145.
 Magurran A. Ecological Diversity and its Measurements. London, Sydney, Croom Helm; 1988.
 Gove IH, Patil GP, Swindel BF, Taille C. Ecological Diversity and Forest Management. Handbook of Statistic 12, Patil GP, Rao CR, editors. Amsterdam, London, New York, Tokyo: Elsevier Science; 1994;12:409-462. DOI: 10.1016/S0169-7161(05)80014-8.
 Krebs CJ. Ecology. The Experimental Analysis of Distribution and Abundance. Harper-Collins College Publishers; New York; 1994.
 Lamb EG, Bayne E, Holloway G, Schieck J, Boutin S, Herbers J, et al. Indices for monitoring biodiversity change: Are some more effective than others? Ecol Indicators. 2009;9(3):432-444. DOI: 10.1016/j.ecolind.2008.06.001.
 Patil GP, Taillie C. An overview of diversity. In: Ecological Diversity in Theory and Practice. Grassle JF, Patil GP, Smith W, Taillie C, editors. Fairland, MD: International Co-operative Publishing House; 1979: 23-48.
 Patil GP, Taillie C. Diversity as a concept and its measurement. J Amer Statist Assoc. 1982;77(379):548-567. DOI: 10.2307/2287709.
 Patil GP, Taillie C. A study of diversity profiles and orderings for a bird community in the vicinity of Colstrip, Montana. In: Patil GP, Rosenzweig ML, editors. Contemporary Quantitative Ecology and Related Econometrics. Fairland, MD: International Co-operative Publishing House; 1979: 23-48.
 Swindel BF, Lloyd R, Patil GP, Taillie C, Conde L. U.S. National Forest Management Act, forest ecosystems diversity and diversity profiles. Conenoses. 1987;2(1):1-8.
 Ten Brink BJE, Hosper SH, Colijn F. A quantitative method for description and assessment of ecosystems: the AMOEBA - approach. Marine Pollut Bull. 1991;23:265-270. DOI: 10.1016/0025-326X(91)90685-L.
 Lane WEM, Peters JS. Ecological objectives for management purposes: applying the amoeba approach. J Aquatic Ecos Health. 1993;2:277-286.
 Wefering FM, Danielson LE, White NM. Using the AMOEBA approach to measure progress toward ecosystem sustainability within a shellfish restoration project in North Carolina. Ecol Modelling. 2000;130(1-3):157-166. DOI: 10.1016/S0304-3800(00)00205-2.
 Collie JS, Gislason H, Vinther M. Using AMOEBAs to display multispecies, multifleet fisheries advice. ICES J Marine Sci. 2003;60(4):709-720. DOI: 10.1016/S1054-3139(03)00042-0.
 Chao A, Gotelli NJ, Hsieh TC, Sander EL, Ma KH, Colwell RK, et al. Rarefaction and extrapolation with Hill numbers: a framework for sampling and estimation in species diversity studies. Ecol Monographs 2014;84(1):45-67. DOI: 10.1890/13-0133.1.