Understanding biodiversity is critical in ecological research because it unravels the role of each single species in the ecosystem in mediating the environment for the entire biological community. The microalgal biodiversity of a region has economic value and, hence, any loss in biodiversity is of serious economic concern. This emphasizes the need and importance of biodiversity conservation. A survey of the literature on microalgae diversity during the past four decades has revealed that ecosystems harbor a large number of algae belonging to various groups. Despite the availability of elaborate monographs on specific groups of algae, any significant amounts of literature on the taxonomy of several algal species and genera remain scarce and scattered.

Proper identification of the algal taxa has always been considered “not an easy task.” Biochemical investigations of, and research into, environmentally important organisms have diversified phycological research and allowed it to enter a whole new phase altogether. Discovery of the potential of microalgae for industrial production of certain chemicals of pharmaceutical value led to the involvement of multifari­ous types of scientists in understanding the algae. Researchers on the threshold of algal taxonomic study and nonbotanists who are intrigued to know about the algae for pursuing research of their own interest are overwhelmed by the huge literature available. The present work therefore is an attempt to bring together a basic way of identifying all microalgae belonging to many of the genera of various groups of algae that occur abundantly and commonly in all ecosystems. Photographs were prepared for various groups of algae as described here. These photographs con­tain taxonomic information on the individual groups of organisms, especially the identification of genera and species. Different species of microalgae were recorded from water samples. All species of microalgae belonged to two major groups of algae, namely Bacillariophyceae and Dinophyceae. The Bacillariophyceae mem­bers were represented by Mastogloia paradoxa Grun., Rhabdonema adriatium Ktz., Synedra gruvei Grunow, Chaetoceros orientalis Schiller, Nitzschia draveillensis Coste & Ricard, Pleurosigma formosum Wm. Smith, Coscinodiscus janischii var. arafurensis Grun., Cocconeis scutellum Ehrenb., Podocystis spathulata (Shadbolt) Van Heurck, Actinocylus octonarius Ehrenb., Biddulphia biddulphiana (Smith) Boyer, Thalassionema nitzshioides Grun., Rhizosolenia setigera Brightwell, and Thalassiothrix longissima Cleve & Grun. The Dinoflagellates are represented by Ceratium hirundinella (Muller) Dujardin, Ceratium longipeps (Bailey) Grun., Ceratium trichoceros (Ehrenberg) Kofoid, and Gymnodinium sanguineum Hirasaka (Figures 2.1, 2.2, 2.3, and 2.4; see color insert) (Rajkumar, 2010).