Marine algae represent itself as potential sources of various useful products. They also exhibit considerable variation in their stress metabolites and enzymatic activity in stressed conditions. In this present study benthic macro-algae of Sunderban Ecosystem has been examined for biochemical characterization with respect to changing physico chemical properties of estuarine water. Chapter 1 contains a short introduction to the topic and discusses the utilization potentialities of marine algae. Chapter 2 discusses the review in details of previous scientific researches on biochemistry of marine algae. Chapter 3 describes the objectives of the study. Chapter 4 discusses the procedures followed for the study. Chapter 5 examines the results of the benthic algal biochemistry of the three seasons. In the last part of this chapter Seasonal Variation of the different parameters of the algal genera with respect to Salinity presented. Chapter 6 condenses the expanded discussion of the observations of the present study pointing at the most important ones. Chapter 8 gives the list of reference actually seen and cross referred for completion of the study.