Abundance, diversity, and trophic state status of estuary based on Bacillariophyta using eDNA method in Jakarta Bay, Indonesia

Abstract Bacillariophyta, also known as diatoms, are a group of microscopic algae found in marine aquatic environments. The presence of these diatoms is a bioindicator to determine the trophic state status of waters, including Jakarta Bay, which is known for the pollution phenomenon occurring in the area. Therefore, this study aimed to identify the abundance and diversity of diatoms, as well as assess the trophic status based on the number of species found in the coastal waters of Jakarta Bay. An environmental DNA (eDNA) method was adopted with seawater samples from three stations, namely Muara Baru, Muara Angke, and Pantai Indah Kapuk. The results showed that Cyclotella sp., Skeletonema sp., and Minutocellus sp. dominated the aquatic environment with relative abundance values of 24-153 ind/L, 1-82 ind/L, and 18 ind/L, respectively. Based on ecological indices, the diatom groups in this aquatic environment have moderate diversity, high evenness with a stable community, and a tendency towards low dominance. The determination of the trophic state status at the coastal waters location using the Nygaard index method showed a value of 0-30.8, suggesting the occurrence of eutrophication. This eutrophication condition was suspected to imply high organic matter, either at the river mouths due to accumulation from waters or wastewater discharge around the sampling area.