<![CDATA[Macrobiofouling is a major problem for maritime infrastructure, as it can cause structural fragility and corrosion of concrete substrates. This study aims to analyse the species diversity, density, and abundance of macrobiofouling on concrete piers, and descriptively examine their association with water quality parameters in the coastal waters of West Aceh (Kuala Bubon Port and Jetty Port) and Aceh Jaya (Calang Port). Sampling was conducted using a purposive sampling method, with two stages of data collection. The first stage was an analysis of species density and diversity index (H') using a 20 × 90 cm quadrat transect, conducted at 10 stations in Kuala Bubon Port to describe the distribution pattern of macrobiofouling communities. The second stage was an analysis of macrobiofouling abundance using a 30 × 30 cm quadrat transect, conducted at three stations representing Kuala Bubon Port, Jetty Port, and Calang Port, while also examining the environmental conditions co-occurring with abundance patterns, based on water quality parameters (temperature, salinity, pH, DO, BOD, clarity, nitrate, phosphate, and current) measured directly on site. The research results identified ten macrobiofouling species, dominated by Balanus sp. The diversity index (H') ranged from 1.67–1.68 (low category), with densities ranging from 3.11–3.33 individuals/m². The abundance of macrobiofouling ranged from 2,011–5,955 individuals/m², with the highest value found at Calang Port, which also exhibited relatively higher current velocity and greater water clarity than the other stations, describing the spatial variation in macrobiofouling abundance and environmental conditions among sampling stations without implying any statistical association or causal relationship.]]>
