INTRODUCTION

Macrophytes are aquatic and amphibious plants found in the littoral zones of running waters (eg. rivers, streams, and the like) and shallow lakes contributing largely to the autochthonous carbon pool and oxygen budget of the aquatic ecosystem. Macrophytes have diverse species of microalgae attached to submerged plant parts which have been shown to be an important productive component of the aquatic ecosystem (Sheldon and Boylen, 1975). Algal epiphytes form a matrix system of several species of microalgae, bacteria and filamentous fungi attached to aquatic macrophytes. These algae are regarded as primary species in different aquatic ecosystem and are involved in maintaining ecological balance among the different groups of macrophytes and aquatic organisms. Several observational and experimental studies on ecological status of bodies of water showed an increase in the population and diversity of algal epiphytes in response to nutrient loading and pollution (Fawzy, 2016). This led to the consideration of these organisms as excellent bioindicators of environmental and water quality alterations because of its sensitivity to external sources of pollution (Fawzy, 2016). Diversity and ecological studies of epiphytic microalgae of different aquatic macrophytes found in rivers and lakes in the Philippines remain poorly understood. To date, no documented taxonomic survey was conducted on these group of microalgae. Thus, additional taxonomic survey of algal epiphytes of different aquatic macrophytes found in these aquatic ecosystems are needed to deepen our understanding of the diversity and ecological roles of these microorganisms. The goal of this investigation is to account the species diversity of algal epiphytes associated to different aquatic macrophytes observed in Laguna de Bay, the largest lake in the Philippines. Also, a brief description of the sampling sites and ecological condition of its existence were documented.