AQUATIC FLORA OF PULICAT LAKE, NELLORE DISTRICT, ANDHRA PRADESH S.K.M.BASHA, E.RAJYALAKSHMI, P.UMA MAHESWARI NBKR Medicinal Plant Research Centre, Vidyanagar – 524413, SPSR, Nellore (Dt) Mail : firstname.lastname@example.org, Swathisayani@yahoo.co.in ABSTRACT Aquatic plants are those which grows in or near water and are either emergent, submergent, suspened or floating type. They exists in two forms namely microphytes and macrophytes. Microphytes include microscopic, uni or multicellular primitive algal forms called phytoplankton. The intensive growth of Phytoplankton causes colouration of the pond.They grow vigorously in the months of septermber to February and provide food for migratory birds. Macrophytes include large, advanced angiosperms . Pulicat Lake is the second largest Brackish water lagoon after Chilika lake of Orissa along the east coast of India. Brackish water is water that is saltier than fresh water but not as salty as sea water Esturies and lagoons have brackish water which shows high biological productivity than fresh or sea water. The International Union for the Conservation of Nature and Natural Resources (IUCN) recently declared the Pullicat lagoon system a Ramsar site of International Importance. Present study aims to explore the aquatic flora of the lagoon especially macrophytes which helps to maintain the biodiversity of the lagoon. Key words ; Aquatic flora – pulicat lake – Microphytes – Macrophytes Introduction Pulicat lake derived its name from a vernacular name „Palaverkadu‟ means plants with many number of roots. Those plants are mangroves with aerial roots called Pneumatophores. The word mangrove is considered to be a combination of the Portuguese word “Mangue” and English Word “Grove”. These are salt tolerant plants and are rich in this area and might be the reason for that name. The lake harbours rich and valued floristic wealth because of its varied ecological habitat viz., salt marshes, canals, mangroves, islands, low lying areas etc. A careful study of literature revealed that the lake has hardly received attention by the botanical explorers and hence it has remained botanically under-explored so far. But its fauna was extensively studied by many zoologists Nanda Kumar et.al . A.R.KSastry and T.A. Rao (1973) in their extensive study on the flora and vegetation of Coastal Andhra Pradesh, have recorded about 15 species from the island of the lake. STUDY AREA; Pulicat lake derived its name from a vernacular name „Palaverkadu‟ means plants with many number of roots. The lagoon‟s boundary limits range between 13.33° to 13.66° N and 80.23° to 80.25°E, with a dried part of the lagoon extending up to 14.0°N.; with about 84% of the lagoon in Andhra Pradesh and 16% in Tamil Nadu. The large spindle- shaped barrier island named Sriharikota separates the lake from the Bay of Bengal. Area Three major Rivers which feed the lagoon are Arani river, Kalangi river and Swarmukhi river. The Buckingham Canal, a navigation Channel is part of the lagoon on its western side. It is connected to the sea through three tidal inlets, one each at Tupilipalem, Rayadoruvu and Pulilcat villages respectively, from north to south. MATERIALS AND METHODS ; Study was undertaken in the Pulicat lake and data of aquatic flora collected by frequent visits during 2009-2010. Close up Photographs of as many as possible and associations depicting the richness of the macrophytes of the lake were taken. Herbaria of various aquatic plants also collected for future reference. Herbaria-specimens are preserved at N.B.K.R. Medicinal Plant Research Centre, Vidyanagar, Nellore District. Results and Discussions Brackish water is more saltier than fresh water and less saltier than sea water. Hence it is biologically more productive than either freshwater or sea water. It shows very rich aquatic population diversity including free floating, submerged, suspended, marginal, amphibious plants along with halophytes and mangroves. Region of pulicat lake includes salt marshes, canals and mangroves. Salt marshes often inundated by backwaters are mostly occupied by halophytes. They include Aleuropous lagopoides, Etriplex repens, Cressa cretica, Crotalaria retusa, Cyparus haspan, Fimbristylils ferrugenea, Salilchornia brachiata , Sesuvium portulacastrum Etc. Similar halophytic species scattered along the banks of Buckingham canal and Vapenjeri canal flowing with brackish water. Halophila ovalis popularly called sea grass belong to the family Hydrochariticeae appear prominently all along the margins Buckingham canal. Small mangrove pockets are located at two places namely near Vepenjeri canal close to Chandrasikuppam, and near Chengalpalem. Four species of mangroves belonging to four families are prominent over here. They include Aegiceras corniculatus of Myrsiraceae, Avicennia marina of Aviceiniaceae, Excoecaria agallocha of Euphorbiaceae and Lumintzera racemosa of Combretaceae. They develop pneumatophores in response to oxygen deficient conditions Significance of macrophytes to the lake: Macrophytes provide cover for fish and substrate for aquatic invertebrates, produce oxygen and act as food for some fish and wild life. Established mangrove roots provide an oyster habitat and slow water flow, there by enhancing sediment deposition. The fine anoxic sediments under mangroves act as sinks for a variety of heavy (trace) metal with colloidal particles in the sediments scavenged from the water. They protect coastal areas from erosion, storms and tsunamis. Their massive root systems are efficient at dissipating wave energy. Conclusion A decline in the macrophytic population may indicate water quality problem. They may be the result of excessive turbidgidy, pollutants including herbicides or salinization. It may lead to a major socio economic problem. One village in Tamilnadu was protected from tsunami destruction. That village is Naluvedapathy planted 80.244 saplings to get into the Guinness Book of World Records. This created a kilometer wide belt of trees of various varieties. When the tsunami struck, much of the land around the village was flooded but the village escaped form minimal damage. Many conservative methods have to be practiced to protect the macrophytic flora of the lake.