Microbial community structure associated with submarine groundwater discharge in northern Java (Indonesia)

Area of Science:

• Environmental Microbiology
• Marine Biology
• Hydrogeology

Background:

• Submarine groundwater discharge (SGD) is a significant pathway for pollutants into marine environments globally.
• Southeast Asia is a hypothesized hotspot for SGD, yet microbial studies remain limited.
• Understanding microbial communities in SGD is crucial for coastal water quality assessment.

Purpose of the Study:

• To investigate microbial community composition along the hydrological continuum of a tropical SGD site in Indonesia.
• To identify key environmental factors influencing microbial community structure in SGD.
• To assess the potential role of SGD in transporting microbial contaminants.

Main Methods:

• 16S rRNA gene sequencing was employed to analyze microbial communities.
• Samples were collected along a hydrological gradient from terrestrial groundwater to offshore SGD.
• Environmental parameters including salinity and temperature were measured.

Main Results:

• Salinity and temperature were the primary drivers of microbial community composition.
• Burkholderiaceae dominated low-salinity groundwater and brackish pore water.
• Synechococcus sp. CC9902 characterized saline SGD and seawater, indicating hydrological influences.

Conclusions:

• Microbial community analysis effectively delineates hydrological processes and water quality at SGD sites.
• Distinct microbial taxa indicate the influence of terrestrial groundwater and seawater recirculation.
• While fecal indicators and potential pathogens were detected, SGD's role as a conduit requires further investigation.