Marine bacteria play an important role in organic matter and nutrient cycling in the upper ocean and thereby maintain biomass production of photosynthetic microorganisms. Most of the bacteria in the ocean are motile and show chemotaxis, i.e. directed swimming behavior towards nutrient hotspots such as phytoplankton and organic matter aggregates (marine snow). These microscale interactions are greatly determined by physical constraints, i.e. low Reynolds number and the sinking behavior of marine snow aggregates in the presence of density gradients. Bacterial activity can also greatly modify aggregates features and hence the magnitude of organic matter and nutrients released into the surrounding water as well as particle sinking to the deep ocean. Therefore, it is of great interest to better understand microbial behavior at living and non-living surfaces where microbial interactions and activities are greatly intensified. This also includes artificial surfaces such as plastics and microplastics, which accumulate and persist in the ocean for extended time spans. Yet, little is known about microbial colonization and interactions at these artificial surfaces and how they modify the natural balance of biochemical processes. Therefore, I will present a conceptual frame work on how physics and microbiology interact with each other and as a consequence modify microbial cycling of organic matter and nutrients in the ocean. Relating ocean physics to microbial processes at the microscale has been shown to be fruitful for better understanding possible ecological and biochemical consequences of various, ever increasing anthropogenic disturbances.
About the speaker
Prof. Dr. Hans-Peter Grossart is Professor of Biodiversity and Microbial Ecology at the University of Potsdam and heads the Aquatic Microbial Ecology group at the Institute of Freshwater Ecology and Inland Fisheries at Lake Stechlin, Germany. Prof. Grossart’s group uses molecular and microbiology techniques to study macroscopic organic aggregates, community structures of organisms in various aquatic ecosystems, and the diversity and role of fungi in aquatic ecosystems. Prof. Grossart serves as panel and board member of different international organizations including the Association for the Sciences of Oceanography and Limnology.