My primary interest is in how planktonic bacterial communities (the relative proportions of bacterial taxa we find in a given environment ) vary across time and how environmental factors shape this variability. I have compiled and investigated a ten year dataset describing the structure of microbial communities and environmental factors throughout the water column in the San Pedro Channel. I use statistical approaches to investigate seasonal and long term variability of communities at several depths. I am particularly interested in applying network analysis, a technique that provides the ability to summarize many statistical associations at once, to investigate association patterns between microbes throughout the water column.
Microbial communities are likely shaped not only by bottom up factors (nutrient availability, temperature, light, etc.) but also by top down controls such as predation (protists, infection by viruses) and direct interactions with other microorganisms. To investigate how these factors shape microbial community structure, I have applied dilution experiments, where I artificially decrease encounter rates between microorganisms in a controlled manner. By combining these experiments and long term datasets, I hope to illuminate why marine microbial communities are structured as they are.