"Blue-green algae (Cyanoprokaryota) are increasingly gaining importance in view of health hazards and ecological risks caused by secondary metabolites with toxic properties named “cyanotoxins”. More than 40 Cyanoprokaryota species are capable to form blooms and produce cyanotoxins. The most common and well-studied producers of cyanotoxins are Microcystis aeruginosa, Aphanisomenon flos-aquae, Anabaena flos-aquae, Cylindrospermopsis raciborskii, Planktothrix agardhii, Lyngbya majuscula, Nodularia and Oscillatoria. Yet, Cyanoprokaryota, often detected in the Bulgarian water bodies, are not studied in toxicological aspects. Therefore, the main goal of this project on the one hand is to identify and characterize the blue-green algae distributed in different Bulgarian freshwater bodies (especially those used for potable and recreational purposes as well as fish-ponds) and on the other hand, to examine their ability to produce intracellular and extracellular toxins. Also, implications on human health and ecological risks caused by harmful freshwater algal blooms will be evaluated and perilous water bodies will be noted and mapped. Correlation between the capacity of toxin production and different environmental factors will be analyzed by ecological models as well as mimicking some environmental factors in in vitro conditions. Collected cyanoprokaryotic samples will be identified by the classical morphological method and if it is necessary by molecular-genetic methods. Determined Cyanoprokaryota species will be adjusted for in vitro culturing and used to study their toxic potential. The toxicity of algal extracts and collected natural water samples will be tested by combination of different in vitro biological assays (enzymatic activity, viability of different cell lines) and the toxins will be identified using ELISA and HPLC methods."