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Coupling between microbial assemblages and environmental drivers along a tropical estuarine gradient
Sara Soria-Píriz1, Virginia Aguilar2, Sokratis Papaspyrou1
1Departamento de Biología, Facultad de Ciencias Marinas y Ambientales, Universidad de Cádiz, Pol. Río San Pedro s/n 11510 Puerto Real, Cádiz, Spain; Instituto Universitario de Investigación Marina (INMAR), Campus Universitario de Puerto Real, Universidad de Cádiz, Pol. Río San Pedro s/n 11510 Puerto Real, Cádiz, Spain.
The Science of the Total Environment
|November 3, 2024
Summary
Microbial community structure and single-cell traits varied seasonally and spatially in the Gulf of Nicoya estuary. Dry season conditions revealed stronger coupling between phytoplankton and bacterioplankton, influencing ecological networks.
Area of Science:
- Marine microbial ecology
- Estuarine biogeochemistry
- Plankton community dynamics
Background:
- Microbial communities (phytoplankton and bacterioplankton) are crucial for energy transfer and organic matter fate.
- Community structure traditionally focuses on abundance, but physiological and single-cell properties also regulate ecological dynamics.
- Understanding these properties is key to a comprehensive view of microbial community structure.
Purpose of the Study:
- To investigate seasonal and spatial changes in microbial community structure, including abundance and single-cell characteristics, along an estuarine gradient.
- To assess the degree of coupling between phytoplankton and bacterioplankton assemblages.
- To correlate microbial community structure with environmental variables.
Main Methods:
- Flow cytometry was used to measure abundance and single-cell characteristics of picocyanobacteria, picoeukaryotes, nanoeukaryotes, and heterotrophic bacteria.
- Sampling was conducted during rainy and dry seasons across the estuarine gradient of the inner Gulf of Nicoya.
- Environmental variables (salinity, DOC, DIN, PO43-, net community production) were measured.
Main Results:
- Spatiotemporal distribution patterns of microbial assemblages differed between surface and bottom waters and varied seasonally.
- Microbial community structure changes correlated significantly with environmental variables, particularly during the dry season.
- A higher degree of coupling, characterized by abundance and single-cell traits, was observed between phytoplankton and bacterioplankton during the dry season, indicating a more complex ecological network.
Conclusions:
- Environmental factors, especially river flow-driven changes in salinity and nutrient availability, significantly impact microbial community structure and regulation in the estuary.
- Single-cell properties provide valuable insights into microbial community structure and ecological regulation beyond mere abundance.
- The dry season promotes a more tightly coupled and complex microbial ecological network in the Gulf of Nicoya estuary.
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