STUDIES ON THE ECOLOGY OF CYANOPHYCEAN BLOOMS

The ecological aspects of five Blue-green algal blooms, viz. Merismopedia tenuissima (Lemmermann), Chroococcus dispersus (Keissel) Lemmermann, Arthrospira glenkinii (Kuffareth), Anabaenopsis massartii (Miller) and Coelosphaerium pallidum (Lemmermann), were studied in relation to certain physico-chemical factors. All the species were found in the form of uni-algal blooms in five different ponds. All the habitats harbouring these algae were rich in HCO3- C1-, Ca2+ and dissolved organic matter (DOM). The PO43- concentrations were high in the case of Arthrospira and Anabaenopsis and low in Merismopedia, Chroococcus and Coelosphaerium habitats. To evaluate the relative importance of various physico-chemical factors on the growth and development of these algal blooms, multiple regression analysis was employed. The high content of DOM stimulated the growth of these blooms significantly. High chloride content was found to be toxic to the algal growth. Both nitrates and phosphates together contributed significantly to the proliferation of Arthrospira, whereas it was nitrates in case of Merismopedia and Anabaenopsis and phosphates in case of Chroococcus and Coelosphaerium that influenced the growth.