Integrated macroinvertebrate and physicochemical assessment of water quality in the Tangka River, South Sulawesi, Indonesia

Abstract

Abstract. Nurman, Syahribulan, Ambeng. 2026. Integrated macroinvertebrate and physicochemical assessment of water quality in the Tangka River, South Sulawesi, Indonesia. Biodiversitas 27 (9): d270923. https://doi.org/10.13057/biodiv/d270923. Benthic macroinvertebrates integrate environmental conditions over time and complement instantaneous physicochemical measurements in river monitoring. This study assessed the Tangka River, Tombolopao Sub-district, Gowa District, South Sulawesi, Indonesia, using macroinvertebrate community metrics, the Family Biotic Index (FBI) and ten physicochemical variables. Five stations representing contrasting riparian land uses were sampled on consecutive days in early August 2022, with three replicates per station. Forty-six families were recorded; family richness increased from 19 at Stations 1 and 2 to 36 at Station 5, and this ranking persisted after rarefaction and coverage standardization (sample coverage ≥99.4%). Replicate-level Shannon diversity ranged from 2.03 to 2.45, evenness from 0.74 to 0.82 and Simpson dominance from 0.11 to 0.18. FBI values (3.23-4.95) classified Station 2 as excellent, Stations 3 and 4 as very good and Stations 1 and 5 as good, indicating that some organic pollution is probable at the latter two; however, only the Station 1 classification was robust to excluding semi-aquatic Hemiptera, which lowered Station 5 to very good. pH, total dissolved solids (TDS), dissolved oxygen (DO) and nutrient concentrations met national Class I criteria, whereas chemical oxygen demand (COD) exceeded the 20 mg L⁻¹ typical of unpolluted water at four stations (20.5-33.2 mg L⁻¹) but was lowest at Station 1, so the biotic and chemical signals did not coincide spatially. Station 1 was characterized by pollution-tolerant gastropods, leeches and oligochaetes, whereas Stations 4 and 5 had the greatest EPT (Ephemeroptera, Plecoptera, Trichoptera) family richness. The results provide a single-season baseline, suggest possible localized organic enrichment at Station 1, and indicate that FBI classes based on imported tolerance values should be accompanied by sensitivity checks before use in monitoring Indonesian rivers.

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