| dc.description.abstracteng | This study about mangrove crabs diversity as bio-indicator for the ecology of mangrove ecosystems was established at Gam Bay-Sawinggrai Research Station, Raja Ampat, Papua, from 2th May- 11 June 2011. In order to indentify the number of crab diversity and density, and then to describes the mangrove crab diversity as the bio-indicator for assessing the current ecological conditions of mangrove ecosystems. By using the point transects, quadrat, point center quarters, stratify transects design, and the rank of disturbances at 10 stations, 40 transects, 160 points, and 160 quadrats. As the results: 5 families, 9 genus, 15 species of true mangrove tree, the total individual is about 585, and then 10 families, 10 genus, 11 associated mangrove species, total individual 38 have recorded. We gets Shannon-Wiener index is about 2.411, and the Simpson index is 0.854, and the Margalef index is 3.884. However, Ceriops decandra is the new species, therefore the numbers of mangroves diversity in Raja Ampat should change became 26 species. Gam Bay preserves 4 super families, 7 families, 12 genus, and 53 species of mangrove crab, and the total population is about 2846 individual, and we had Shannon-Wiener index is about 4.823, Simpson index is 0,954, and Margalef is 6.538. On the whole we had high diversity and richness of mangrove crab and mangroves trees in Gam Bay. The linear regression analysis and Pearson’s index shows, mangroves diversity and crabs community (diversity, richness, and density) have significant relationship. Therefore we are going to reject H0 and accept H1. The high diversity, richness, density of mangrove crabs indicates a mangrove ecosystem has low density, high diversity and richness of mangrove trees, and also high diversity of crab habitats, this is appropriate for the coastline mangrove ecosystem. While, low diversity, richness, density of mangrove crabs indicates a mangrove ecosystem has high density, low diversity and richness of mangrove trees, and low diversity of crab habitats, this is suitable for the riverine mangrove ecosystem. The islands and the coves mangrove forests are compatible for both typical of ecological and biological correlation. Therefore crab diversity as the biological indicator is useful to describe the ecological conditions of particular mangrove forest area. The contribution of Ocypodidae and Sesarmidae crabs as the greatest population is significant on these relationships. But the future researchs needed, in order to compare this conclusion with other location which has high or moderate level of disturbances and to clarify the relationship between the diversity and density of mangrove trees and crabs density. We verified mangrove ecosystems still capable to provide a suitable fundamental niche for mangrove crab species, the current disturbances in Gam Bay are under the carrying capacity, yet the integrity and stability of mangrove ecosystems are secure from being degradation | de |