Design and testing of DNA microarrays to monitor microbial diversity with adequate biodiversity indexes, using cyanobacteria in freshwater as a model system. For microorganisms, biodiversity assessments and conservation studies need molecular tools and criteria because phenotypic information is of limited value. We will develop indicators of biodiversity based on the emerging technology of DNA miniarrays and compare their performance against classical approaches. The biological modelwill be the dynamics of populations of cyanobacteria in aquatic habitats which suffer periodic onset of blooms. To develop the DNA miniarrays, molecular analyses based on taxonomic markers like rRNA will give the sequence data needed to design oligos to detect cyanobacteria. To evaluate the ability of the DNA chips to quantify biodiversity and monitor change, the data obtained by different phenotypic (countings, cultivation) and genotypic approaches will be analyzed using a software specially designed to use molecular data to calculate biodiversity indices and OTU richness. Participation with other european laboratories,MIDI-CHIP: Consiglio Nazionale delle Ricerche (CNR-ITBA) (I) University of Helsinki (UHE) (FIN) Finnish Environment Institute (FEI) (FIN) Consiglio Nazionale delle Ricerche (CNR-CSMA) (I) Azienda Multiservizi Intercomunale-Consorzio (AMI) (I) PISCES Conservation Ltd (UK) Centre de Recherche Public-Gabriel Lippman (CRP-GL) (Lx) University of South Bohemia (U.South Bohem.) (CZ)