Hydrobiologia 506–509: 519–524, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands. 519 Littoral diatoms as indicators for the eutrophication of shallow lakes Miloslav Kitner & Aloisie Poul´ ı˘ ckov´ a Department of Botany, Faculty of Sciences, Palack´ y University, Svobody 26, CZ – 771 46 Olomouc, Czech Republic E-mail: kitner@prfholnt.upol.cz Key words: diatoms, eutrophication, epilithon, epiphyton, epipelon, fishponds, bioindication Abstract The littoral zone of shallow water bodies in the Czech Republic has been studied quite consistently at several fishponds. The use of algae, especially diatoms, for the monitoring of the state of lotic freshwater also has a long tradition. The main objective of the presented paper is to validate the feasibility of the use of littoral periphyton comunities for the biomonitoring of standing waters. At the investigated sites, littoral periphytic diatoms were studied together with selected enviromental variables (pH, conductivity, nutrients – especially total phosphorus) on three types of natural substrates (epilithon, epiphyton, epipelon). The evaluation of the diatom community was performed on the basis of the checklists of algal indicator species published by authors from the Czech Republic, Austria and the Netherlands. The data were subjected to statistical software NCCS 2000 (GLM Anova and “Ward’s minimum” variance cluster analysis). Littoral periphytic diatoms appear to be good indicators of the fishpond water quality. The selected substrates show non-significant differences therefore the average values from all substrates were used. The best indicatory system for evaluation of Czech fishponds was van Dam’s index. Introduction The sensitivity of algae, especially diatoms, to eu- trophication has been proved and is commonly used in different ecological and paleoecological investiga- tions (Stoermer & Smol, 1999; Ács et al., 2003). The composition of diatom communities reflects an entire complex of ecological parameters at a particular site (van Dam, 1982). Phytoplankton of lakes and periphyton of running waters turned out to be reliable enviromental tools when estimating different levels of eutrophication. However, a possible use of periphyton for the assess- ment of the eutrophication degree in stagnant water bodies has not been verified sufficiently yet (Kiss et al., 2003). This study aims (1) to verify the ability of littoral periphytic diatom assemblages to asses the trophic status of shallow lakes (fishponds); (2) to select the best sampling method and substrate for this type of monitoring (stones = epilithon, plants = epiphyton, sediments = epipelon); (3) to select the best indicat- ory system for this type of ecosystem – trophic diatom index (T R ) followed by Rott (1999), trophic diatom index (T V ) followed by van Dam et al. (1994) or sap- robity index (S S ) followed by Sláde˘ cek & Sláde˘ cková (1996). Methods Altogether 15 localities (Central Moravia, Czech Re- public) were investigated during the end of recre- ational season – september 2001. Table 1 summarizes the characters (Type 1–4) and enviromental variables of the sites. In situ, we measured conductivity, and pH with mobile instruments (WTW Company). We took water samples for chemical analysis in 500 ml glass bottles 10 cm under the water surface using standard methods (Hindák, 1978). We analysed nutrient content by spec- trophotometric methods using chemical sets of HACH company. At each site, we took one sample of wa- ter for chemical analysis and three samples of algae from three types of substrate (epilithon, epiphyton, epipelon), if available. Each sample represented a mix- ture from several stones, plant stems or places of the