Conclusions

Dwindling stock of fossil fuels with the threat of changes in the climate necessitated exploration of renewable, viable and sustainable feedstocks capable of providing self-reliant energy solutions, especially of those from algae-based biofuels. However, economic viability has been posing a major challenge in realizing large scale production of biofuels from microalgae. In view of this, the present research focused on understanding the ecological characteristics and growth patterns of estuarine benthic diatoms under varying loads of nutrients in real-time conditions. Efforts towards understanding the regional dynamics of diatom community structure, their habitat preferences and tolerance towards fluctuating environmental conditions would greatly help in gaining knowledge on species-specific abundances, especially those of benthic diatoms in one or more habitats of a complex natural ecosystem like the tropical estuary of the Aganashini river, in relation varying levels of nutrient concentrations and other physico-chemical parameters. Canonical correspondence analysis results of the present study demarcated tolerant clusters of diatoms over the sensitive ones, that can withstand highly fluctuating environmental conditions prevailed in the lentic and lotic system. Hierarchical clustering revealed highly productive clusters that are capable of accumulating higher lipids under certain environmental conditions over other species. Regression modeling performed to understand the probable lipid productivity potential by integrating physico-chemical and nutrient parameter, provided an empirical equation relating lipid and other critical factors affecting lipid content of diatoms. This empirical modeling is capable of providing lipid content details right at the sampling stage without cultivating diatoms under laboratory conditions. Thus, the multivariate statistical tools were utilized in the present study to extract valuable leads towards selection of candidate species/consortium of species for large-scale production in future microalgal based third generation biofuels production systems.