Summary
In the microscopic realm the physics are not always as we experience them in our everyday life. For example, inertia is unimportant, while the viscosity of the fluid affects every single aspect of the life of a microbe, from food acquisition to swimming. And yet, viscosity is a property that has been traditionally neglected in oceanography because in pure seawater it is well constrained by temperature, salinity and pressure. However, in the ocean water is not pure, and among many compounds there are a lot of exopolymeric substances (EPS), released largely by marine microbes, that can alter the bulk viscosity at scales of tens of meters. The role of these EPS at the scale of microorganisms remains hypothetical. To address this I have adapted a technique, common in biophysics and biomedicine but new to oceanography: microrheology. This technique allows me to map viscosity with micron resolution around phytoplankton cells and inside marine aggregates. These maps have revealed the existence of steep gradients of viscosity at the ocean microscale that, as my numerical models show, can alter the dynamics and conformation of the chemical landscape and affect the motility of bacteria and their ability to obtain resources. Altogether this suggests that secreting EPS could be an engineering tool that gives phytoplankton cells a measure of control of their immediate surroundings and allows them to cultivate their own garden of bacteria.
Brief biography
I am a plankton ecologist broadly interested in the interlinks between biological, physical and chemical variances at the microscale. I am currently a research fellow at the School of Life Sciences at the University of Lincoln, UK. My research focuses primarily on microbial ecology, physical-biological interactions and ecological time series. My research is interdisciplinary: it involves the study of purely physical and chemical problems, such as small-scale turbulence, viscosity, ocean acidification or nutrient stoichiometry, but also of ecological processes, interactions and responses with evolutionary implications, such as bacterivory, nutrient uptake, chemotaxis, motility and microbial shape diversity. Throughout my career I have explored these questions in different research groups with leading international experts on small-scale physical-biological interactions. I did my doctorate at the Institute of Marine Sciences of Barcelona (ICM-CSIC) about the effects of variability in turbulence and in nutrient inputs on the dynamics of coastal planktonic communities. After completing the doctorate in 2008 I moved to the U.S., where I did first a postdoc at the College of Earth Oceanic and Atmospheric Sciences (Oregon State University), and at the Hawai’i Institute of Marine Biology (University of Hawai'i at Mānoa) later. Since 2013 I am a research fellow in the Physical Ecology Lab in Lincoln, where I am pioneering the use of microrheology to study the role of viscosity in microbial ecology.