A quantitative morphological and ecological study of protozoa polluting tap water in Mexico City.

RIVERA, F., ORTEGA, A., LÓPEZ-OCHOTERENA, E. & PAZ, M. E. 1979. A quantitative morphological and ecological study of protozoa polluting tap water in Mexico City. Trans. Amer. Micros. Soc., 98: 465469. The stiidy was performed using samples obtained from the tap water of the most populated area of the Federal District in Mexico City. The organisms were concentrated through filtration procedures and subsequently cultured in sterile wheat infusions. The cultures were obsemed for a week and the taxonomic identification was achieved to the leve1 of genus and species. Most commonly found were flagellates (84.58%), followed by amoebae (13.38%) and ciliates (1.86%). The greatest number (17) of species were found in the eastern region of the Federal District, though 16 were taken from the central region. Richest in numbers of organisms per m1 were Bodo edux (8636/m1), cysts of flagellates and ciliates (4484/m1), cysts of amoebae of the Vahlkampfiidae (2083/m1), and trophozoites of the genus Vahlkanapfru itself (14081ml). Among detected species, only those belonging to the Vahlkampfiidae and Hartmannellidae might have pathogenic effect on human beings. However, several species were found red which denotes a high degree of organic pollution in the supposedly potable waters of the Federal District.