Analyze of Environmental Sensitivity Indeks Method for Mangrove Ecosystem Againt Oil Spills. Case Study at Subang District Coastal Zone

Abstract

Mangrove ecosystem is one of the coastal ecosystems that very vulnerable to oil spills. Oil spill on mangrove ecosystem can cause direct mortality. Oil polution in the long term on mangrove ecosystem can disturb another organism that live in mangrove, also influencing socio-economic life of people who depend their life to mangrove ecosystem. With the result that, efforts to prevent or minimize the risk of oil spills in coastal areas is needed. Enviromental sensitivity index (ESI) is an index that can determine the sensitivity level of environmental to oil spills. This research aims to develop environmental sensitivity index of mangrove ecosystem in the coastal area of Subang, West Java Province to oil spill. Types of data were used in this study consists of primary data and secondary data. Primary data was obtained by survey in the field, while secondary data was obtained by literature study. Primary data was collected including mangrove ecosystem data, type of substrates, and socio-economics data that related to mangrove ecosystem. While secondary data was including coastal physical characteristics and hydrooceanography. These data were used to form ESI parameters. Furthermore the ESI was applied in the studied area and then the sensitivity area was shown on ESI map. The ESI was comprised of three types of index consist of vulnerability index (VI), ecology index (EI), and socio-economic index (SI). The paramaters of VI consist of slope, tides, tidal range, height of wave, type of substrate, and mangrove distance from the coast. The parameters of EI consist of mangrove zonation, density of mangrove, diversity of mangroves, stage of mangrove, protected wildlife, and status of mangrove protection. The parameters of SI consists of two components including social and economic components. The social component was based on mangrove resource utilization by human, such as fisheries potential, wood potential, and tourism potential, while the economic component was counting from biomass of mangrove. The formula of ESI was used is ( ) ( ) it divided into 5 sensitivity levels (not sensitive, less sensitive, moderate, sensitive and very sensitive). Generally coastal areas of Subang were slightly slope, mixed semidiurnal of tidal type, average wave height is 0.4 meters, muddy substrate and mangrove found in the shoreline. In observation areas founded three genus of mangrove (Avicennia sp, Sonneratia sp, and Rhizophora sp.) with different densities. The mangrove ecosystem at Subang is protected area. Protected wildlife did not found on mangrove ecosystem. Mangrove used for fisheries activities (as an area of ponds, catching eels and crabs) and the use of wood (as fuelwood, building materials, materials for fishing gear). The ESI aplication on mangrove ecosystem in observation areas showed that some mangrove have sensitive and moderate ESI level. The most of areas moderate to oil spill except to Tegal Tike, Anggaranu, and Tanjung. These area are sensitive to oil spill