Chennai: Researchers from the Indian Institute of Technology Madras (IIT Madras) have uncovered the important role of rare marine microorganisms in maintaining the stability of ocean ecosystems through an analysis of bacterial sequencing data from more than 4,600 ocean samples worldwide.

The study, carried out by researchers from IIT Madras' Wadhwani School of Data Science and AI, integrated publicly available microbial sequencing data collected from tropical, temperate and polar regions. The findings provide insights into how marine bacterial communities assemble, interact and remain stable across diverse environments.

The research was published in mSystems, a peer-reviewed open-access journal of the American Society for Microbiology. The paper was co-authored by Pranathi Ravikumar, Aarti Ravindran and Karthik Raman from IIT Madras.

The researchers found that rare "specialist" bacteria, despite occurring in much lower abundance than widespread "generalist" species, play a disproportionately important role in ecosystem stability. Computational analyses showed that removing these specialist bacteria substantially weakened microbial interaction networks, highlighting their role in maintaining resilient marine ecosystems.

"Marine microorganisms form the invisible foundation of ocean ecosystems. They regulate nutrient cycling, sustain marine food webs and play a vital role in controlling the Earth's climate," Karthik Raman, Wadhwani School of Data Science and AI, IIT Madras, said.

He said understanding the processes governing the formation and resilience of microbial communities on a global scale could help inform efforts to conserve ocean health.

Aarti Ravindran, postdoctoral researcher at WSAI, said marine microbial communities were largely shaped by random ecological processes, but the balance between randomness and environmental selection varied across latitude zones.

Polar microbial communities exhibited more modular interaction networks, while tropical and temperate communities were influenced by both environmental selection and stochastic ecological processes, she said.

The researchers used neutral community modelling, phylogenetic community assembly analysis and microbial co-occurrence network analysis to examine the presence, interactions and ecological roles of marine microorganisms.

The findings could help scientists monitor biodiversity, track ecosystem changes and support conservation and environmental management. The researchers said future studies could expand the geographic and temporal scope of sampling and examine microbial communities at species- and strain-level resolution.