LAUSR

The present study unravels the microalgal diversity and dynamics of a tropical estuarine ecosystem (Muttukadu, of Indian south east coast) and applies tools like isolation of useful species to utilize in aquaculture as well as to conserve the native strains. The study was carried out for a period of 18 months. Selected diversity indices (Simpson index, Dominance index, Shannon- Weiner index, Pielou’s evenness index and Margalef richness index) were used to describe the trends of diversity in the estuary during the study period. Spatial and temporal changes in microalgal diversity in the estuary were analysed. Sixty three species of microalgae belonging to Chlorophyceae, Bacillariophyceae, Cyanophyceae, Dinophyceae, Euglenophyceae, Eustigmatophyceae, Prymnesiophyceae, Prasinophyceae and Zygnematophyceae were identified. Out of these, members of Bacillariophyceae formed the dominant flora (48.5%) with twenty six species, followed by Cyanophyceae (29.2%) and Chlorophyceae (13.6%). The species diversity was increased after the flood during December-2015 in south east coast of India. More than two dozens of microalgal strains useful for larval nutrition in aquaculture were isolated during the study period. Nutrient profiling of isolates revealed the presence of essential fatty acids (EPA & DHA) in high percentage in some of the isolates. Altogether, the present study is the first report of this kind from Muttukadu which gives the insight on a) the seasonal changes in abundance of microalgae species in a tropical estuary and b) suitable time for the isolation of potential species for aquaculture and conservation of various species in the laboratory conditions.