Scientists have identified freshwater sponges and their associated microbial communities as powerful natural allies in tackling toxic metal pollution, offering new hope for sustainable water quality management. A recent study has revealed that these sponges can act both as bioindicators and effective absorbents of harmful metals such as arsenic, lead and cadmium.

The findings come from a study published in Microbiology Spectrum by researchers from Bose Institute, an autonomous institute under the Department of Science and Technology, Government of India. The research focused on freshwater sponges from the Sundarban delta, an ecologically sensitive and underexplored region facing increasing pollution pressure.

Led by Dr Abhrajyoti Ghosh, Department of Biological Sciences, the study demonstrated that sponge-associated microbial communities play a crucial ecological role in detoxifying polluted waters and supporting ecosystem health. The work was supported by a DST SERB National Post-Doctoral Fellowship awarded to Dr Dhruba Bhattacharya and marks the first report on bacterial diversity in freshwater sponges from the Sundarbans.

Researchers found that the microbial communities hosted by sponges are distinct from those present in surrounding water bodies and are shaped by both sponge species and habitat. Significantly, the sponges were shown to accumulate much higher concentrations of toxic metals than the ambient environment, highlighting their strong bioaccumulation capacity. This is particularly relevant given the widespread heavy metal contamination across the Gangetic plain.

Beyond metal accumulation, the study revealed that sponge-associated bacteria are enriched with genes linked to metal ion transport, metal resistance and antimicrobial resistance. These functional traits suggest that microbial symbionts actively contribute to detoxification processes and help sponges survive in contaminated environments.

The research underscores the ecological importance of the sponge–microbe partnership and reinforces the potential of freshwater sponges as reliable bioindicators for monitoring pollution. The findings also open new avenues for nature-based bioremediation strategies aimed at restoring polluted freshwater and estuarine ecosystems.