Taxonomy and periodicity of Chlorococcum fries, Coelastrum Näg. and Scenedesmus Meyen in Hooghly, West Bengal, India


Chlorococcum humicola (Näg.) Rabenh., Coelastrum astroideum De Notaris, Scenedesmus bijuga var. irregularis (Wille) G. M. Smith and Comasiella arcuata var. platydisca (G. M. Smith) E. Hegewald & M. Wolf are very common freshwater Chlorococcalean algal taxa in the geographical occurrence of Hooghly district, West Bengal, India. The members of the order Chlorococcales exhibited wide morphological diversity in shape and size of vegetative cells and, colonies. They reproduced mainly by autospores. Besides these, they also propagated by zoospores or aplanospores. During the taxonomic investigation, it was noticed that the above said species were grown better in lentic aquatic bodies as well as most of the taxa showed higher periodicity in hot and humid monsoon (August) and summer (March- April). Except, Chlorococcum humicola (Näg.) Rabenh. other three algal taxa are coenobial types. Scenedesmus Meyen colony is flat, whereas Coelastrum Näg. is spherical in a morphological point of view. It was also observed that the two varieties of the genus Scenedesmus Meyen occurred in polluted water bodies, so they are good ecological indicator of water pollution. All these taxa are being reported first time from this area and Comasiella arcuata var. platydisca (G.M. Smith) E. Hegewald & M. Wolf and, Coelastrum astroideum De Notaris for the first time from West Bengal. The study of physicochemical parameters of water bodies showed that they can tolerate the fluccuation of chemical oxygen demand values. Higher temperature (˃25°C), moderate alkalinity (<8.5), dissolved oxygen values above 6.0 mg/l and lower inorganic nutrient contents as well as turbidity accelerated their occurrences, growths and periodicities in aquatic bodies.