Bacterial Community Composition in the Sea Surface Microlayer Off the Peruvian Coast

Area of Science:

• Marine microbiology
• Air-sea interface science
• Biogeochemistry

Background:

• The sea surface microlayer (SML) is a critical interface influencing air-sea exchange.
• Bacterial communities (bacterioneuston) in the SML play a role in these processes.
• Factors like organic matter, UV radiation, and wind speed are thought to shape bacterioneuston.

Purpose of the Study:

• To analyze the bacterial community composition in the SML and underlying water (ULW).
• To investigate the role of Transparent Exopolymer Particles (TEP) and nutrient concentrations in SML bacterial assembly.
• To understand the environmental drivers controlling bacterioneuston in the Peruvian upwelling region.

Main Methods:

• Bacterial community composition analysis using 16S rRNA gene sequencing.
• Quantification of Transparent Exopolymer Particles (TEP) abundance.
• Measurement of nutrient concentrations and salinity in SML and ULW.

Main Results:

• Bacterioneuston and bacterioplankton communities showed similarity, indicating spatial coupling.
• Four Bacteroidetes families, notably Flavobacteriaceae and Cryomorphaceae, were enriched in the SML.
• SML-enriched bacteria correlated negatively with SML temperature and wind speed, and positively with ULW nutrient concentrations and salinity.

Conclusions:

• Bacterioneuston community structure is influenced by a combination of SML and underlying water conditions.
• Nutrient availability and salinity in the ULW are key factors driving the enrichment of specific bacterial families in the SML.
• The findings highlight the importance of upwelling dynamics in shaping SML microbial communities.