Distribution patterns and the biomass of bivalves at Segoro Tambak estuary, Sedati, Sidoarjo, East Java

Abstract

Indonesia's marine waters have a variety of flora and fauna species that live and associate therein. This study used the observation method and a descriptive analysis. The results showed that the bivalvia distribution pattern in Segoro Tambak Estuary looks diverse with a distribution index value <1 which was in the range of 0.3 - 0.4. The highest average bivalve biomass was temporarily at 2.02 ton/km2, which was in March, and the lowest was 0.95 ton/km2 in January. The highest total average density was temporally 6 ind/10m2 in March and the lowest was 3 ind/10m2 in February. Low wind and current speeds in March caused the highest density and biomass in March. The content of the organic matter such as BOD was in the range of 33.38 to 53.89 mg/l from the threshold of <20 mg/l and the COD was in the range of 242.6-643.11 mg/l from the threshold of 80 mg/l. This far exceeds the threshold, but bivalves can still live in these waters because bivalves are aquatic bioindicators. Bivalve life at Segoro Tambak Estuary is also supported by muddy substrate conditions that are suitable for bivalve life.