Rare marine bacteria hold key to ocean stability: IIT Madras study

CHENNAI: Rare marine bacteria, despite occurring in far smaller numbers than common species, play a crucial role in keeping ocean ecosystems stable, a study by researchers from IIT Madras has found.

The study, led by researchers at the Wadhwani School of Data Science and AI (WSAI), analysed microbial sequencing data from more than 4,600 ocean samples collected across tropical, temperate and polar regions. The analysis offers insights into how marine bacterial communities assemble, interact and maintain resilience in diverse environments.

The research, published in the peer-reviewed journal mSystems, found that rare ‘specialist’ bacteria act as important connectors within microbial interaction networks. Computational analysis showed that removing these organisms substantially weakened network stability, pointing to an ecological role far greater than their abundance would suggest.

“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,” Prof Karthik Raman of WSAI, IIT Madras, said.

He said understanding the formation and resilience of microbial communities globally could help inform efforts to protect ocean health and advance the UN goal of conserving marine ecosystems.

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 latitudes. Polar communities showed more modular interaction networks, while tropical and temperate communities were influenced by both environmental selection and stochastic processes.

The study, co-authored by Pranathi Ravikumar, Aarti Ravindran and Raman, combined neutral community modelling, phylogenetic community assembly analysis and microbial co-occurrence network analysis to examine not only which microorganisms occur in oceans but also how they interact.

The researchers said identifying rare microbial groups that contribute to ecosystem stability could strengthen biodiversity monitoring and conservation efforts, particularly as climate change alters ocean temperatures and marine ecosystems.