Distribution Patterns and Biomass of Bivalve in Juanda and Segoro Tambak Estuary in Sedati, Sidoarjo, East Java

Indonesian waters have a variety of Hora and fauna species that live and associate therein. According to Yunus (2008) and Zarkasyi et al. (2016), the bivalvia group as an organism is generally found in marine waters, especially coastal areas or intertidal areas and is widely used by most people. This research used an observation method with descriptive analysis. The results show that the bivalvia distribution pattern in Juanda and Segoro Tambak rivers' estuaries looks consistent with a distribution index value of <1, which is in the range of 0.3-0.5. The highest average bivalve biomass is temporally at 2.02 ton/km² in March at Segoro Tambak station and the average biomass value of the lowest bivalves is temporally at 0.65 ton/km² in January at Juanda station. The highest total average density is temporally at 6 ind/10m² in March at Segoro Tambak station and the lowest density value is 3 ind/10m² in February at Segoro Tambak station.