Temporal/Spatial Patterns of Diversity
Since 2000, in conjunction with the Caron Lab , the Fuhrman Lab has collected and analyzed water at multiple depths from San Pedro Ocean Time Series (SPOT) as part of the USC Microbial Observatory. Using a combination of molecular tools including gene-specific sequencing (16S rRNA, 18S rRNA, myoviral g23), metagenomics, and transcriptomics, we continue to assess the microbial populations (viral, bacterial, archaeal, eukaryotes) in conjunction with environmental parameters and biological metrics (microscopic and flow cytometric bacteria and virus counts, secondary production rates from thymidine and leucine incorporation, etc.).
The monthly time series enables us to assess long-term patterns and networks of seasonality, co-occurrence, and diversity for all players in the microbial food web. These patterns allow us to use real-world variations of natural complex communities to address fundamental questions about the factors controlling microbial biomass, diversity, activities, and biogeochemical roles.
We are also assessing patterns at different temporal (weekly, daily, sub-daily) and spatial scales (regional to global). Daily time series have shown unexpectedly sudden shifts in microbial communities that were previously missed by more routine monthly or weekly sampling. Our recent work showed that the dominant phytoplankton during the spring bloom can change on a near-daily basis, much more rapidly than first thought, and can include multiple harmful algal bloom species in rapid succession. We also found that Euryarchaea can peak to ~40% of the prokaryote community, in other words these poorly-known microbes can briefly bloom to make up the dominant organism in the near-surface ocean. We also analyze our data in the context of regional and global diversity patterns via our own sampling of three regional sites, which include SPOT plus a site in the Port of Los Angeles as well as a matched site near relatively pristine Catalina Island. In addition, we compare our data to those from major global sampling networks, such as the Earth Microbiome Project, and Ocean Sampling Day, both of which Dr. Fuhrman serves as a scientific advisor.