In the two earlier communications (SEENAYYA, 1971) physicochemical complexes of three freshwater ponds and the ecology of Volvocales, Chlorococcales, Desmids and Euglenineae of these waters were discussed . This article presents the ecological behaviour of diatoms and blue-green algae in those bodies of water . It also includes a list of algae which occured in significant numbers during the two years period of observation .
DIATOMS Distribution
The ponds under investigation differed distinctly from each other in oxidizable and nitrogenous organic matter, inorganic carbon, nitrogen and phosphorus . They harboured different diatom forms and differed in the average bulk of diatoms and their percentages in the overall phytoplankton populations (Table I) . Golkonda pond with abnormally high concentrations of oxidizable and nitrogenous organic matter, inorganic carbon, nitrogen and phosphates, possessed only six species of diatoms, which formed about 1 .4 percent of the phytoplankton . In contrast to this, Hydrilla pond with comparatively less concentrations of oxidizable and nitrogenous organic matter, inorganic carbon, nitrogen and phosphorus showed approximately 50 species of diatoms which constituted the major bulk of the phytoplankton . This suggests that a number of diatom species avoided the highly polluted Golkonda pond . This confirms HUSTEDT (1932) and FJERDINGSTAD (1950) who observe that diatoms do not