STRUKTUR KOMUNITAS MAKROZOOBENTOS SEBAGAI BIOINDIKATOR KUALITAS SUNGAI INDRAGIRI KECAMATAN INUMAN

Abstract

The Indragiri River in Inuman Subdistrict, Riau, faces ecological pressures due to human activities such as domestic activities, agriculture, settlements, and unauthorized gold mining (PETI). These activities can reduce the physicochemical quality of the water and affect aquatic organisms. Macrozoobenthos, benthic organisms sensitive to changes in water quality, are used as bioindicators of aquatic conditions. This study aims to analyze the macrozoobenthos community structure through species composition, diversity index (H’), evenness (E), dominance (C), and physicochemical water parameters. The research employed a descriptive quantitative method, with sampling conducted at three stations (upstream, midstream, downstream) and subsequent laboratory analysis. The results revealed nine species from five classes, with Gastropoda being the dominant class (40.75%). Station I (upstream) exhibited the highest diversity (H' = 2.05) and the lowest dominance (C = 0.14), whereas Station II (midstream) had the lowest diversity (H' = 0.68) with moderate dominance (C = 0.51). Station II was classified as moderately to heavily polluted, indicated by low DO (3.34 mg/L) and BOD, COD, and TSS exceeding the water quality standards stipulated in Indonesian Government Regulation No. 22 of 2021. A research gap exists as heavy metals such as mercury have not yet been analyzed, suggesting that future studies could expand chemical indicators for a more comprehensive environmental assessment.