Metagenomic analysis of plankton and bacterial communities in the seaweed culture environment of Kepulauan Seribu, Indonesia

Seaweed production in Indonesia has experienced a significant decline of 3.55% over the past five years, with a drastic reduction in the Kepulauan Seribu region, where output dropped from 196 tons in 2018 to 2 tons in 2022. Understanding the biological and environmental parameters that support seaweed cultivation, particularly microbial and plankton diversity, is essential for sustainable production. This study, conducted on Kappaphycus alvarezii (Doty) Doty ex P.C.Silva, 1996 cultivation sites across Kepulauan Seribu during the 2023 rainy seasons (April–May) and dry seasons (July–August), involved water quality assessment and biological sampling at twelve points near five key islands. Next-generation sequencing (NGS) of bacterial communities revealed that Alphaproteobacteria, particularly Rhodobacteriaceae, dominated across seasons, while zooplankton was prevalent during the rainy season, and phytoplankton during the dry season. Harmful algae and pathogenic bacteria were absent in the samples, indicating a generally safe environment for seaweed growth. Although some anthropogenic pollution was detected through elevated oil content and chlorophyll-a, overall water quality was deemed suitable for seaweed cultivation. The findings suggest that, with appropriate management to mitigate pollution, the Kepulauan Seribu region retains a strong potential for sustainable seaweed culture.