Community Structure of Benthic Macroinvertebrates as Bioindicators of Water Quality in the Upstream Setail River, Banyuwangi, East Java, Indonesia

Setail River is the longest river in Banyuwangi Regency, East Java. The current condition of Setail River is experiencing an alarming decline in water quality due to the activities of the surrounding community. This decline in water quality can have a negative impact on aquatic biota. To assess water quality, one of the methods used is to use biological indicators, namely benthic macroinvertebrates. The purpose of this study was to assess water quality in the upstream to middle reaches of the Setail River using benthic macroinvertebrates as bioindicators. The assessment was carried out based on community structure, the Biological Monitoring Working Party-Average Score Per Taxon (BMWP-ASPT) method and water physicochemical parameters. This study was conducted at 5 sampling points. Upstream to midstream of the Setail River waters, benthic macroinvertebrate communities were found consisting of 3 classes, 25 families from 10 orders, namely Trichoptera, Ephemeroptera, Diptera, Coleoptera, Plecoptera, Odonata, Lepidoptera, Lumbriculida, Littorinimorpha and Basommatophora. The abundance of benthic macroinvertebrates ranges from 62-451 individuals/m². The diversity of benthic macroinvertebrates ranges from 0.85-2.55 (low-moderate). The evennes index value ranges from 0.43-0.88 (low-high), while the dominance index at station V (0.66) is classified as high (C > 0.5) since at this station there is dominance by one family, namely Hydrobiidae from the Gastropoda class. The ASPT value for each sampling point ranges from 4.4-6.9, indicating that the water conditions vary from clean water, doubtful quality to probable moderate pollution depending on the sampling point. These results indicate that the water quality ranges from very good to moderate pollution, especially at Sampling Points III and V. Based on the analysis of the effects of activities around the river, it causes changes in the composition and structure of benthic fauna. Management activities (campaigns for the community to avoid river pollution) are needed to restore and maintain the quality of the environment and our results can contribute information to these activities.