Population Structure of Parasesarma brevicristatum and Parasesarma semperi as an Indicator of Mangrove Replanted Forest Condition in Bintuni Bay, Indonesia

Abstract The mangrove forest at Bintuni Bay is one of the largest in Indonesia, and a portion of it is being used as production forest to produce woodchips. Replanting in the production forest results in various ecosystem conditions through ages. Since the Sesarmidae crab is an important component of the mangrove ecosystem and contributes significantly to its energy cycle, it is frequently used as a bioindicator to evaluate the ecosystem’s health. In the production mangrove area of Perseroan Terbatas Bintuni Utama Pure Wood Industries, sampling was done using the purposive sample method with circular plots in natural mangrove forests, replanted trees aged 25 and 5 years, and forests that had just been harvested. According to the survey, station 3′s five-year-old replanting of P. brevicristatum and P. semperi crabs had a population density of 139,455 Ind.ha −1 while station 4′s damaged forest had a population density of 119,047 Ind.ha −1 . Both varieties of crabs have a higher male to female sex ratio. It was discovered that young individuals dominated the two species of crabs’ size distribution. Both species of crabs’ length weight relationships displayed a positive allometric tendency. The density of the saplings was the element of the mangrove vegetation that had the greatest impact on the population structure of both crabs.