1 VERTICAL DISTRIBUTION OF MACRO BENTHOS IN MANGROVE AREA OF MAVINHOLE CREEK, KARWAR, KARNATAKA, INDIA. A. S. Musale* and J. L. Rathod and P.N.Mesta Dept. of Marine Biology, School of Ocean Sciences Karnatak University Post Graduate Center, Karwar-03, India e-mail : musale_amar@yahoo.com, amarmusale@rediffmail.com ABSTRACT The mangrove ecosystem eventually provides an excellent supply of organic detritus matter as food. Benthic organisms continuously restructure or bring about mixing of the sediments by means of locomotion, ingestion, ejection and respiration and recognized as one of the major processes altering the primary structure of sedimentary deposits on millimeter to meter scales. These benthic organisms play an important functional role in estuaries and other aquatic ecosystems. They alter geochemical conditions at the sediment-water interface, promote decomposition and nutrient recycling, and transfer energy to other food web components. So an attempt is made to study vertical distribution of benthic Macrofauna in Mavinhole creek and find out the qualitative and quantitative distribution of biotic community i.e. benthic Macrofauna and some of abiotic factors. Benthic Macrofauna comprised of 13 groups namely Foraminifera, coelenterate, Nematoda, Polychaeta, Worms, Gastropoda, Bivalvia, Copepoda, Amphipoda, Isopoda, Penaeidae, Insects and Crustacea. In Macrofauna Polychaeta ranked first in numerical abundance, followed by Nematoda. I I N NT TR RO OD DU UC CT TI I O ON N Mangroves are the forest ecosystem of tropical and subtropical regions of the world. A rich biodiversity is observed in the mangroves. Creeks are areas where huge amount of organic detritus is build up, a considerable quantity sinks to the bottom together with phytoplankton cell and zooplankton feces, finally to rest on the sediment water interface. Thus even if estuarine floor doesn’t have primary production of its own, it gets large quantity of organic matter by sinking and horizontal transport, on which a vast variety of bottom living organisms subsist and they are popularly called as BENTHOS. The role of benthic communities living in the mangrove forest is the transfer of energy from mangrove to the estuarine ecosystem. Secondly the benthic organisms not only support the fishery potential by producing millions of larva in the form of microplankters and also, maintain the state of equilibrium of ecosystem by producing burrows, pumping air and water within. The district has a coastline of about 144- km in length, which extends from Majali in the northern boundary to Bhatkal in the south. The Karwar coast is enriched by the riverine discharge of Kali River. So far no work has been done regarding the vertical distribution of benthic fauna in Mavinhole creek. To find out the qualitative and quantitative distribution of biotic community i.e. benthic fauna and abiotic factors like temperature, D.O., Salinity and pH three Stations were selected. M MA AT TE ER RI I A AL L A AN ND D M ME ET TH HO OD DS S Karwar is one of the major fishing Centre situated in latitude 14°15′ N Longitude 74°03′ E located in the District of Uttar Kannada of Karnataka state. In the present investigation three study Stations were selected. Station # 1 - Mavinhole creek , Station # 2 – Near Devbagh Bridge. Station # 3 – Near Halebagh. Fortnightly sediment and water sample was carried out