Collaborative research: Microbial dynamics on marine snow particles

College Of William & Mary Virginia Institute Of Marine Science, Gloucester Point VA

Investigators

Abstract

Marine snow fluxes sequester carbon to the deep ocean, significantly buffering the greenhouse effect. In response to continuing global warming, large-scale ocean fertilization has been proposed as a way to enhance marine snow fluxes and remove extra atmospheric CO2. Marine snow particles harbor high densities of bacteria and other microbes, whose activities modify the physical and chemical characteristics of the particles. Understanding these processes is critical to predicting the fate of marine snow fluxes in the ocean. This project is aimed at a mechanistic understanding of the microbial dynamics on marine snow particles, using an innovative approach of combining experiments, observations and modeling. This project is 1) characterizing the time-dependent microbial dynamics on marine snow particles, 2) investigating how different biotic and abiotic factors modify the dynamics, and 3) developing mathematical models to quantitatively describe such dynamics. Lab-generated diatom aggregates are being used to test encounter models for predicting the rate at which bacteria colonize marine snow. Agar-aggregates are being used to examine bacterial chemosensory response to marine snow chemicals, and the effects of the bacterial physiological status on the colonization process. Predator-prey dynamics on snow particles are being investigated by grazing experiments with bacterivorous protists. Field studies are following the changes in bacterial colonization behavior, size and morphology of natural marine snow and the associated microbes during the course of an algal bloom. Laboratory and field observations are being used to test and expand colonization models in order to describe microbial dynamics on marine snow based on hydrodynamics, microbial behavior, growth and interspecific interactions. These models are being integrated with coagulation models to study how marine snow formation coupled with microbial dynamics affects marine snow and carbon fluxes in the water column. This project is extending the existing collaborations between VIMS, TAMU and three outstanding European research institutions. Graduate research training and education are integral parts of the project. To promote ethnic diversity and leadership training in marine sciences, minority undergraduates are being recruited through a new internship program DREAMS to participate in the project and gains hands-on research experience. The PIs are developing education materials for the general public with focus on global warming, ocean-climate interactions and ocean fertilization. These materials are being implemented by DREAMS interns in their outreach activities that target grade school students and teachers, allowing them to establish themselves as future leaders in climate issues.