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ABSTRACT Microbial communities play critical roles in ecosystem functioning across a wide range of environmental conditions. The physiological stress imposed by temperature, pH and resource levels can shape the structure and function of microbial communities; however, while often tested independently, factors influencing physiological stress on a community rarely occur in isolation from each other. Controlled experiments simultaneously testing multiple interactive stressors allow researchers to better assess the dynamical responses of microbial communities to rapidly changing environments. Using a full factorial, controlled experiment, we tested three hypotheses for how independent and interactive effects of abiotic stresses impact bacterial community composition, structure and function in a model system. We utilised an aquatic, pitcher plant‐associated bacterial community in which microbial nutrient cycling is essential to the host plant and ecosystem. Temperature, pH and resource (food) concentration had strong independent and interactive effects on bacterial community composition, structure and function. Community functions did not respond to interactive stressors in the same way. Chitinase and protease enzymatic activities had opposite responses to temperature and pH changes, indicating that diverse functional measures are necessary for understanding the varied effects of interacting stressors. The most extreme abiotic stress combination (high temperature, lowest pH and excess food) resulted in the lowest enzyme activity and reduced species richness as compared to the other treatments. Stressful conditions, especially high temperature, strengthened correlations between community structure and function. Higher phylogenetic dispersion under abiotic extremes suggested selection for diverse taxa adapted to similar conditions through convergent evolution. These interactive effects highlight the often greater‐than‐additive impact of multiple stressors and demonstrate that environmental filtering and trait convergence shape microbial responses to stress.
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This content will become publicly available on June 27, 2026
Predation by a ciliate community mediates temperature and nutrient effects on a peatland prey prokaryotic community
ABSTRACT Temperature significantly impacts microbial communities’ composition and function, which plays a vital role in the global carbon cycle that determines climate change. Nutrient influxes often accompany rising temperatures due to human activity. While ecological interactions between different microorganisms could shape their response to environmental change, we do not understand how predation may influence these responses in a warmer and increasingly nutrient-rich world. Here, we assess whether predation by a ciliate community of bacterial consumers influences changes in the diversity, biomass, and function of a freshwater prokaryotic community under different temperature and nutrient conditions. We found that predator presence mediates the effects of temperature and nutrients on the total prokaryotic community biomass and composition through various mechanisms, including direct and indirect effects. However, the total community function was resilient. Our study supports previous findings that temperature and nutrients are essential drivers of microbial community composition and function but also demonstrates how predation can mediate these effects, indicating that the biotic context is as important as the abiotic context to understanding microbial responses to novel climates.IMPORTANCEWhile the importance of the abiotic environment in microbial communities has long been acknowledged, how prevalent ecological interactions like predation may influence these microbial community responses to shifting abiotic conditions is largely unknown. Our study addresses the complex interplay between temperature, nutrients, predation, and their joint effects on microbial community diversity and function. Our findings suggest that while temperature and nutrients are fundamental drivers of microbial community dynamics, the presence of predators significantly alters these responses. Our study underscores the impact of abiotic factors on microbial communities and the importance of accounting for the biotic context in which these occur to understand, let alone predict, these responses properly.
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- Award ID(s):
- 2224819
- PAR ID:
- 10618222
- Editor(s):
- McMahon, Katherine
- Publisher / Repository:
- mSphere
- Date Published:
- Journal Name:
- mSphere
- ISSN:
- 2379-5042
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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