Microbial ecology of shallow groundwater ecosystems.

Shallow groundwater ecosystems host microbial communities with greater diversity than surface environments, but their active biogeochemical processes remain poorly quantified.

• Why it matters: Understanding microbial roles in groundwater is crucial because these ecosystems are vital freshwater sources and are increasingly threatened by pollution and climate change, yet their microbial functions are not well understood.
• What they did: The review discusses microbial community dynamics in shallow aquifers, emphasizing the influence of hydrogeological settings, energy availability, redox conditions, climate, and human activities, with a focus on microbial biodiversity and key processes like carbon cycling.
• The result: Findings highlight the need for more quantitative data on active microbial processes and the ecological roles of viruses, protists, and fungi, which could inform management of groundwater resources under environmental pressures.