Gastropods as bioindicators of heavy metal pollution in the Banyuasin estuary shrimp pond area, South Sumatra, Indonesia

Abstract

The supply of shrimp ponds water sources in this research utilizes water input from the waters of the Banyuasin River Estuary, which brings in heavy metal pollutant particles due to anthropogenic pressure. The potential for accumulation of heavy metals can occur in gastropods which are bioindicators of the pond environment. In this study, we present data on gastropods abundance and community structure concerning environmental physicochemical factors and heavy metal accumulation. Sampling was carried out in November 2021 at five observation stations spread over three shrimp ponds. The collection of gastropod samples used two methods based on achievement targets. The gastropod ecology index calculated the abundance, diversity (H′) values of heavy metals analyzed, namely Pb, Hg, Cu, and Cd. Wet digestion with an acid solution of HNO₃ and HClO was performed before measuring the concentration on the Atomic Absorption Spectrophotometer (Shimadzu AA-7000). Furthermore, all data on environmental variables were analyzed by principal components analysis (PCA) to determine the leading variable group for each station. A cluster was formed based on the Bray-Curtis similarity analysis. The results of the gastropod ecology index as a bioindicator showed moderate and low diversity (H′) and evenness (J) values, while dominance (D) was high and moderate. From two species analyzed for heavy metals, Nerita violacea and Telescopium telescopium contained Pb, Hg, and Cu concentrations, but no Cd levels were detected, including in water and sediment. Accumulation of heavy metals in shrimp ponds is not only due to the mass movement of tidal water, some of which contribute, namely the location of the inlet and outlet waterways and the position of the land to the main canal source. In general, these results indicate that the environmental conditions of the pond have accumulated heavy metal pollutants, but its whereabouts cannot be ascertained all the time. These results are sufficient to describe the current situation but need further study its impact on aquaculture production.