SEAGRASS COMMUNITY STRUCTURE IN TUNDA ISLAND GULF OF BANTEN

Abstract

Seagrass, as an aquatic angiosperms which are completely adapted to live in the marine environment and shallow water estuaries, is one of the most highly productive marine ecosystems. Under the increasing of global water temperature, coupled with nutrient over-enrichment, the community structure of seagrass may transform as the alteration of ecological functions followed. This condition may also happen in Indonesian coastal waters, including Tunda Island on the Gulf of Banten which received excessive nutrients from the mainland. Study of seagrass community in Tunda Island has been carried out using line transect method perpendicularly to the shore with the 1x1 meter transect plots within 10 meters interval. Community structure as density, coverage, diversity index and dominance index of seagrass had been observed in 4 stations. The results showed that there were five species of seagrass were recorded in this area, namely Cymodocea rotundata, Syringodium isoetifolium, Enhalus acoroides, Halophila ovalis and Thalassia hemprichii. The distributions and species composition were varied and generally dominated by Thalassia hemprichii with 48.25 shoots m*² density. The diversity index obtained from the research was 0.84 as well as the dominance index was 0.55. It showed that the diversity of seagrass at Tunda Island is low and no high dominance among species. The status of seagrass meadows in Tunda Island was classified as poor since the total coverage was only 22 %. Further observation of correlation among other organisms such as macroalgae and grazers in the ecosystems will be necessary to investigate the ecological alteration.