Marine microbes are tiny, they span only about 1/100 the diameter of a human hair, but they are very abundant in our oceans, accounting for over 90% of the biomass. They control the productivity and chemistry of the ocean at global scales, and as a consequence oceanographers have traditionally studied marine microbial processes over large space (meters and litres) and time scales (days to years). However, many of the ecological interactions and chemical transformations that drive ocean-scale processes occur at microbial scales (micrometres and microliters), within settings that occupy only a fraction of a single drop of seawater.
Within this microscale world, marine microbes experience and exploit a seascape of localized resource hotspots and interact with one another within cell-cell scenarios. The sum of these microscale events ultimately shapes bulk seawater chemistry, meaning that microliter processes may profoundly influence the large-scale function of the ocean.
Studying these important microscale processes with traditional oceanographic equipment is logistically impossible, so our project aims to develop new tools and analytical approaches to gain the first view of the ocean from a microbe’s perspective. Our objectives are to:
1.Develop new microfluidic experimental platforms that allow us to manipulate ocean chemistry at the microscale in situ
2.Use these experimental platforms to examine how microbial behaviours and physiological responses, such as motility, chemical attraction and gene expression, allow natural populations of marine microbes to prosper within a heterogeneous microscale seascape.
3.Develop new genomic approaches for examining the composition and functional capacity of microbial communities within very small volumes of seawater
To determine the biogeochemical consequences of these microscale processes, which are typically ‘averaged out’ by standard oceanographic sampling and analysis protocols, we aim to apply the methods we develop to:
1.Decipher the ecological interactions underpinning bacterial-phytoplankton associations in the ocean
2.Reveal the temporal dynamics of microbial gene expression in response to localized chemical pulses
3.Examine how microscale chemical cycling processes scale up to affect ocean biogeochemistry
Our hope is that these microscale experiments will provide exciting new viewpoints for understanding the roles and influence of microbes in the ocean.