EN
Water blooms are usually connected with cyanoprokaryote or algal mass occurrence, however, some other phenomena may also cause an intensive water colour in lakes. Common and characteristic water bloom is often brought about by mass oc-currence of tree pollens, abundant occurrence of fungal spores or, at deeper water layers, besides algae also some green or red sulphur bacteria. The most characteristic blooming algae belong to cyanoprokaryotes, but this phenomenon can be also caused by other taxa e.g. green algae, euglenophytes and chloromonads.