Researchers at the Wadhwani School of Data Science and AI (WSAI), IIT Madras have uncovered a crucial role played by rare marine microorganisms in maintaining the stability and resilience of ocean ecosystems.
The study, which provides a global analysis of marine bacterial communities, integrated microbial sequencing data from more than 4,600 publicly available ocean samples collected across tropical, temperate and polar regions.
The research offers new insights into how marine bacterial communities assemble, interact and maintain stability across diverse ocean environments.
The findings were published in mSystems, a peer-reviewed, open-access journal of the American Society for Microbiology. The paper was co-authored by Pranathi Ravikumar, Dr. Aarti Ravindran and Prof. Karthik Raman of IIT Madras.
Rare bacteria, major ecological role
The researchers found that rare “specialist” bacteria can contribute substantially more to ecosystem stability than their relatively low abundance would suggest.
While widespread “generalist” bacteria occur in much larger numbers, specialist microbes act as important connectors within microbial interaction networks.
Computational analysis showed that removing these specialist bacteria substantially weakened the stability of the networks, pointing to their outsized role in maintaining resilient marine ecosystems.
IIT Madras Wadhwani School of Data Science and AI Prof. Karthik Raman said marine microorganisms form the invisible foundation of ocean ecosystems by regulating nutrient cycling, sustaining marine food webs and helping control Earth’s climate.
He said understanding how these microbial communities form and maintain resilience globally could help inform efforts to conserve ocean health and support the UN’s goals for Life Below Water.
Latitude shapes microbial communities
The study also found differences in how microbial communities are structured across geographical zones.
IIT Madras Postdoctoral Researcher, WSAI, Dr Aarti Ravindran said marine microbial communities are largely shaped by random ecological processes, but the balance between randomness and environmental selection varies across latitudes.
Polar microbial communities showed more modular interaction networks, while tropical and temperate communities were influenced by a combination of environmental selection and stochastic ecological processes.
The researchers combined multiple ecological approaches, including neutral community modelling, phylogenetic community assembly analysis (iCAMP) and microbial co-occurrence network analysis.
Pranathi Ravikumar, Undergraduate Student, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, IIT Madras, said the approach enabled the researchers to go beyond identifying which microorganisms are present and examine how they interact to sustain ecosystem resilience.
Implications for ocean conservation
Healthy oceans are critical to climate regulation, fisheries, biodiversity conservation and global biogeochemical cycles. With climate change altering ocean temperatures and marine ecosystems, understanding microbial community behaviour could help improve predictions of how marine ecosystems respond to environmental disturbances.
The identification of specialist microbial groups as important contributors to ecosystem stability also highlights the potential ecological significance of rare taxa, alongside abundant organisms, in marine conservation.
The researchers said the analytical framework developed in the study could be applied to other environments to monitor biodiversity, track ecosystem changes and support conservation and environmental management.
Future research could expand the geographic and temporal scope of sampling and move towards species- and strain-level analysis, providing a more detailed understanding of microbial community structure, ecological interactions and ecosystem functions.