EPFL BioE Talks SERIES "On Microbes and Particles: The Ocean at the Microscale"
Event details
| Date | 26.05.2025 |
| Hour | 12:15 › 13:15 |
| Speaker | Prof. Roman Stocker, Institute of Environmental Engineering, ETH Zurich (CH) |
| Location | Online |
| Category | Conferences - Seminars |
| Event Language | English |
WEEKLY EPFL BIOE TALKS SERIES (sandwiches provided)
Abstract:
The sinking of organic particles is a main driver of carbon export from the ocean surface to depth, where it can remain stored for centuries. Only a small fraction of the particulate carbon that leaves the surface makes it to the ocean bottom, in part due to degradation of particles by marine bacteria. Yet, the processes by which bacteria find, colonise and degrade particles, and their associated rates, have remained largely unknown. I will present microfluidic experiments at the single-particle level to illustrate the rich interplay between particle dynamics and microbial processes, as well as mathematical models to scale up the observed particle degradation dynamics to predict the vertical carbon flux. I will focus on two findings. First, I will show that the rate of degradation of particles depends on the particle sinking speed, a process we termed ’sinking-enhanced degradation’, which couples two parameters (sinking rate, degradation rate) traditionally considered independent in carbon flux models. Second, I will present evidence that the sinking speed of particles is itself affected by microbial processes, not only through degradation, but also through the scavenging of bogeys of microbial origin, which slow particle descent by increasing drag and buoyancy.
Bio:
Roman Stocker is a professor of environmental engineering at ETH Zurich and formerly at MIT. Roman pioneered a new approach to microbial ecology, based on the combination of microfluidics, video microscopy and mathematical modeling, which allowed him to address a long-standing challenge in oceanography: the need to study marine microbes quantitatively at the single-cell level and with explicit consideration of the highly dynamic processes that shape their lives. This microscale, mechanistic understanding is then used to better understand the myriad of ecological and biogeochemical impacts that microorganisms have at ocean-scale. Roman’s research group, which brings together engineers, physicists, biologists and mathematicians, uses quantitative experiments in the laboratory and in the field in combination with individual-based and continuum models to understand microscale processes in the ocean, including microbial motility and sensing, the role of microbes in the marine carbon cycle, harmful algal blooms, coral disease, oil degradation, viral infection and bacteria–phytoplankton interactions. Roman has brought to the field a unique combination of (1) imaging and image analysis, revealing previously unseen processes; (2) new engineering tools, including microfabrication and 3D printing, providing unprecedented access to quantitative experiments on marine microbes; and (3) an intimate connection between observations and mathematical models, as necessary to identify general principles of microbial ecosystems. More recently, the group has expanded its interests to apply the same integration of different approaches to the study of ecohydraulics, where the effects of fluid flow and transport on aquatic organisms from invertebrates to fish are studied in order to understand the effect of anthropogenic disturbances on freshwater ecosystems. Roman’s work has frequently appeared in high-profile journals including Science, Nature and the Proceedings of the National Academy of Sciences, and has been featured in popular media including the BBC, CNN and The New York Times.
Zoom link (with one-time registration for the whole series) for attending remotely: https://go.epfl.ch/EPFLBioETalks
Instructions for 1st-year Ph.D. students planning to attend this talk, who are under EDBB’s mandatory seminar attendance rule:
IN CASE you cannot attend in-person in the room, please make sure to
Abstract:
The sinking of organic particles is a main driver of carbon export from the ocean surface to depth, where it can remain stored for centuries. Only a small fraction of the particulate carbon that leaves the surface makes it to the ocean bottom, in part due to degradation of particles by marine bacteria. Yet, the processes by which bacteria find, colonise and degrade particles, and their associated rates, have remained largely unknown. I will present microfluidic experiments at the single-particle level to illustrate the rich interplay between particle dynamics and microbial processes, as well as mathematical models to scale up the observed particle degradation dynamics to predict the vertical carbon flux. I will focus on two findings. First, I will show that the rate of degradation of particles depends on the particle sinking speed, a process we termed ’sinking-enhanced degradation’, which couples two parameters (sinking rate, degradation rate) traditionally considered independent in carbon flux models. Second, I will present evidence that the sinking speed of particles is itself affected by microbial processes, not only through degradation, but also through the scavenging of bogeys of microbial origin, which slow particle descent by increasing drag and buoyancy.
Bio:
Roman Stocker is a professor of environmental engineering at ETH Zurich and formerly at MIT. Roman pioneered a new approach to microbial ecology, based on the combination of microfluidics, video microscopy and mathematical modeling, which allowed him to address a long-standing challenge in oceanography: the need to study marine microbes quantitatively at the single-cell level and with explicit consideration of the highly dynamic processes that shape their lives. This microscale, mechanistic understanding is then used to better understand the myriad of ecological and biogeochemical impacts that microorganisms have at ocean-scale. Roman’s research group, which brings together engineers, physicists, biologists and mathematicians, uses quantitative experiments in the laboratory and in the field in combination with individual-based and continuum models to understand microscale processes in the ocean, including microbial motility and sensing, the role of microbes in the marine carbon cycle, harmful algal blooms, coral disease, oil degradation, viral infection and bacteria–phytoplankton interactions. Roman has brought to the field a unique combination of (1) imaging and image analysis, revealing previously unseen processes; (2) new engineering tools, including microfabrication and 3D printing, providing unprecedented access to quantitative experiments on marine microbes; and (3) an intimate connection between observations and mathematical models, as necessary to identify general principles of microbial ecosystems. More recently, the group has expanded its interests to apply the same integration of different approaches to the study of ecohydraulics, where the effects of fluid flow and transport on aquatic organisms from invertebrates to fish are studied in order to understand the effect of anthropogenic disturbances on freshwater ecosystems. Roman’s work has frequently appeared in high-profile journals including Science, Nature and the Proceedings of the National Academy of Sciences, and has been featured in popular media including the BBC, CNN and The New York Times.
Zoom link (with one-time registration for the whole series) for attending remotely: https://go.epfl.ch/EPFLBioETalks
Instructions for 1st-year Ph.D. students planning to attend this talk, who are under EDBB’s mandatory seminar attendance rule:
IN CASE you cannot attend in-person in the room, please make sure to
- send D. Reinhard a note well ahead of time (ideally before seminar day), informing that you plan to attend the talk online, and, during seminar:
- be signed in on Zoom with a recognizable user name (not any alias making it difficult or impossible to identify you).
Practical information
- Informed public
- Registration required
Organizer
- Prof. Anne-Florence Bitbol, Institute of Bioengineering
Contact
- Institute of Bioengineering (IBI), Dietrich REINHARD