Comparative Metabarcoding Analysis of Bacterial Communities and Functional Profiles in the Seaweed and Mangrove Blue Carbon Ecosystems of Goa, India

Seaweed and mangrove ecosystems, as integral components of the blue carbon habitat, play pivotal roles in global carbon sequestration and coastal protection. This study explores the bacterial communities and their functional profiles from the coastal habitats of Goa, emphasising their critical roles in the blue carbon ecosystems. The bacterial diversity based on the metabarcoding analysis of the V3–V4 region of the 16S rRNA gene was assessed from the seaweed habitats at Dona Paula and the mangrove ecosystem at Chorao, Goa. Proteobacteria, Cyanobacteria and Actinobacteria dominated the seaweed ecosystems. In contrast, mangrove ecosystems had a more complex microbiota, including Firmicutes and Planctomycetes, which thrive in anaerobic conditions. A comparative reanalysis of taxonomic and functional profiles from the study locations and seven additional locations from different seaweed and mangrove ecosystems of Goa reported in previous studies was also carried out to understand the temporal changes from 2017 to 2024. The results showed a significant presence of Firmicutes at selected locations, with an increased abundance of pathogenic taxa such as Bacillus, Clostridium and Shewanella. These locations, Anjuna, Hawaii and Bogmolo in the seaweed and Ribandar, Panaji and Campal in the mangrove habitats of Goa, were situated near urban regions and influenced by anthropogenic activities, including tourism and urban runoff. Analysis of the bacterial functional profiles also showed an increased representation of the genes associated with xenobiotic biodegradation pathways in these locations. These findings emphasise the urgent need for effective conservation strategies to protect these vital ecosystems against the rising threats of anthropogenic pressures, pollution and climate change.