Association of Crab Species (Brachyura) Based on Mangrove Density Levels along the Coast of Tugurejo, Semarang, Indonesia

Mangrove ecosystem have ecological functions as a spawning ground, nursery ground, and feeding ground. The purpose of this study was to determine the correlation of an abundance of crabs with the density of mangroves in the mangrove ecosystems of Tugurejo Village, Semarang. This research was hand picking of sampling methods and determining sampling locations using a purposive sampling method. The research location is divided into three stations, namely Station 1 (Non estuary), Station 2 (Transition area), Station 3 (Estuary). Samples were taken from a sampling plot of 10 m x 10 m. The results of this study identified two types of mangroves: Rhizophora mucronata and Avicennia marina. The results of this study found 4 types of crabs including Metaplax elegans, Parasesarma charis, Metopograpsus latifrons, Uca coarctata. The ecological function of crabs in the mangrove ecosystem is as indicator species. The dominant crab species found was Uca coarctata, with a percentage value of 36.25%. The correlation of the abundance of crabs with mangrove density shows that higher the value of mangrove density, make the abundance of crabs increases. The crab abundance value on the coast of Tugurejo Village the lowest was 700 ind/ha, and the highest was 2000 ind/ha.