Macrozoobenthos as a Bioindicator of Water Quality in the Coastal Waters of Merak Besar Island, Banten Province

Abstract

High human activity in the coastal area of Merak Besar Island, Banten Province, such as tourism, port, and industrial activities, potentially degrades water quality and affects benthic organisms that serve as biological indicators of coastal ecosystem health. This study aimed to describe the physicochemical characteristics of the water, total organic matter (TOM), sediment texture, and macrozoobenthos community structure, and to determine the ecological condition of the waters using a macrozoobenthos bioindicator approach based on the AMBI (AZTI's Marine Biotic Index) method. Research was conducted spatially in January 2026 at four stations using 1x1 m² quadrat transects with different numbers of replicates per station, along with measurements of temperature, pH, DO, salinity, TOM, and sediment texture. Results showed physicochemical parameters at all stations remained stable and met seawater quality standards, although DO at one station was exactly at the minimum threshold. Twenty macrozoobenthos species were identified, comprising Group II (indifferent), Group III (tolerant), and Group IV (opportunistic) species, with no Group I or V species recorded, while Littoraria lutea had the highest abundance. Abundance ranged from 558-1,171 ind/m², highest at the least disturbed station. Species diversity was moderate, evenness high, and dominance low across all stations. Although physicochemical conditions were suitable for macrozoobenthos, AMBI values at all stations indicated a slightly polluted category, dominated by Group III. This confirms that macrozoobenthos can detect ecological stress not yet captured by instantaneous physicochemical parameters, making it a useful method for assessing the coastal environmental condition of Merak Besar Island.