Revealing Hidden Diversity in Menjangan Besar Island, Karimunjawa:Reef-Associated Decapods as a Proxy of Biodiversity Estimation

The Indonesian archipelago, with its higher number of Marine Protected Areas (MPA) and National Parks, is a home to a high diversity of marine organisms. Karimunjawa is an Indonesian National Park that is well known for its diverse coral reefs and therefore is an important place to study marine biodiversity. In the present study, the biodiversity of reef organisms was estimated in the coastal marine habitat of Karimunjawa. A semi-quantitative sampling method was used to estimate reef biodiversity using decapod group as a representative. Sixteen similar sized dead coral heads of Pocillopora were sampled from 10 m depth at Menjangan Besar Island, Karimunjawa. All decapods were sorted and identified to the family level, yielding 11 families from total 203-collected individuals. Species richness statistics (Chao1 and ACE) suggest that only 11 families of decapods can be found in this area. Rarefaction curves approached an asymptote after sampling fourteen heads, indicated that sample addition will not alter the estimate diversity found in this location with Shanon-Wiener diversity index of 1.9 indicated low diversity. Our findings may provide a basic understanding of the overall biodiversity of a reef area and a basic knowledge in monitoring coral reefs ecosystems for protection and conservation.