4,600 Ocean Samples Reveal Critical Role of Rare Bacteria in Ecosystem Resilience

Researchers at IIT Madras have uncovered the crucial role played by rare marine microorganisms in maintaining the stability and resilience of ocean ecosystems, offering new insights into how microscopic life supports marine biodiversity.

Researchers from the Wadhwani School of Data Science and AI (WSAI) analysed sequencing data from more than 4,600 publicly available ocean samples collected across tropical, temperate and polar regions. The findings were published in the peer-reviewed journal mSystems, published by the American Society for Microbiology. The study was co-authored by Prof Karthik Raman, postdoctoral researcher Aarti Ravindran and undergraduate student Pranathi Ravikumar. Researchers found that rare “specialist” bacteria contribute significantly more to ecosystem stability than previously recognised.

Although these microorganisms occur in much lower numbers than widespread “generalist” bacteria, they act as important connectors within microbial interaction networks. Computational analysis showed that removing specialist bacteria substantially weakened the stability of these networks, highlighting their outsized role in resilient marine ecosystems. Ravindran said the balance between random ecological processes and environmental selection differs across geographical regions. Polar microbial communities displayed more modular interaction networks, while tropical and temperate communities were shaped by both environmental selection and stochastic ecological processes.

The research combined several advanced ecological methods, including neutral community modelling, phylogenetic community assembly analysis and microbial co-occurrence network analysis, to examine how marine microorganisms interact and sustain ecosystems.

Prof Raman noted that marine microorganisms form the invisible foundation of ocean ecosystems, regulating nutrient cycles, supporting food webs and contributing to climate regulation. The researchers said identifying specialist microbial groups as key contributors to stability highlights the need to consider rare taxa alongside abundant organisms in marine conservation. The computational framework developed through the study could also be adapted to monitor biodiversity and track ecosystem changes across different natural environments, supporting conservation efforts and the UN’s “Life Below Water” goal.