I am presently a graduate student studying with Dr. Dave Caron at the University of Southern California (Los Angeles) in the Marine Environmental Biology Ph.D. program. I have been invited on this cruise to examine the diversity of deep-sea protistan (single-celled eukaryotes) assemblages using molecular (DNA-based) detection techniques. I will be collecting samples from the water column (within the hydrothermal plume) and the benthic community near the vents to assess the protistan diversity and community structure at these sites. Additionally, I will attempt to isolate individual protistan cells from the deep-sea to establish mono-specific cultures to use in future laboratory-based ecological and physiological studies of these organisms. A further role for me will be to assist the other cruise participants with their work wherever there is a need.
What questions are you trying to answer and why?
Recent work in our lab at USC has focused on describing protistan diversity at several deep sites (2,500 meters) in the Sargasso Sea (Northwest Atlantic Ocean) and a research site off the coast of Southern California. Previous studies of protistan diversity, based on observation by light microscopy, have provided a limited description of taxonomic diversity for particular sites. Analysis of sub-cellular morphology by electron microscopy has been more useful for describing protistan taxa, but is extremely labor intensive. For these reasons, we have turned to characterizing complex protistan assemblages using DNA-based technologies. We have detected a number of DNA sequences at our study sites having a high degree of similarity to newly discovered protistan lineages. These new lineages have recently been described by other research groups from sites around the globe (many located in the deep-sea). The size, shape, abundance, and trophic status of these newly described taxa are virtually unknown, with evidence of their existence limited almost exclusively to DNA sequence information. We are broadly interested in describing protistan diversity for the purpose of revealing the microbial community structure at particular sites, characterizing previously unknown taxa and linking morphotypes to their genetic and physiological signatures.
Why is this research important? What are the benefits?
Describing the diversity of protistan assemblages is important for uncovering the range of eukaryotic diversity and determining the function of various ecosystems in the world’s oceans. Protistan diversity is turning out to be much higher than pre-molecular studies would have predicted. This knowledge will help us to understand the evolutionary relationships among eukaryotes and possibly help to explain the origin of life on Earth. Despite these facts, many marine systems lack comprehensive descriptions of the protistan community (e.g., how many different types of organisms are present at a given time?). Phototrophic protists (phytoplankton) are responsible for a majority of the primary production in the euphotic zone (the region of the water column illuminated by solar radiation) while heterotrophic protists feed on other protists and prokaryotes (bacteria and archaea) throughout the water column. Recycling of nutrients and dissolved organic matter by heterotrophic protists can provide a significant source of nitrogen and phosphorous in nutrient-limited systems. Additionally, heterotrophic protists may serve as prey for larger organisms, thereby serving as a conduit for energy transfer from the base of marine food webs to higher trophic levels. Discovering which organisms are present at a given time and location will provide clues for understanding how nutrients and energy cycle through marine ecosystems.
What’s your background and what lured you into marine science/education?
I grew up in New Hampshire, near Lake Winnipesaukee, where I spent many summers exploring the lake with a mask and snorkel. As soon as I turned 16, my Dad and I obtained our SCUBA certifications, which opened up a whole new realm of underwater exploration for us.
I pursued my undergraduate degree in zoology at the University of New Hampshire, where I volunteered in a marine ecology laboratory, studying larval ecology of marine invertebrates and general plankton ecology. In January of 1991, with my undergraduate degree in hand, I left for Bermuda, to begin a six-month volunteer program at the Bermuda Biological Station for Research (BBSR). This program offered free room and board in exchange for work in the lab and provided me with invaluable research experience. My first job in Bermuda involved studying the symbioses between sea anemones and their protistan symbionts (phototrophic dinoflagellates). The volunteer work at BBSR turned into a full-time research technician position, primarily assessing the nutrient chemistry and nutrient utilization by marine microbes at two oceanographic study sites: Hydrostation ‘S’ and the Bermuda Atlantic Time-series Station (BATS). The technician job gave me the opportunity to gain hands-on experience with many aspects of oceanographic measurements including nutrient profiling, phytoplankton and bacterial production, sediment trap collections of sinking biological material, and net tows to collect plankton samples. While I was working at BBSR, I met many scientists who would travel to Bermuda to conduct research at the BATS site. During these cruises I learned as much as possible about the research programs of the visiting scientists and became aware of the importance of the microbial component of marine food webs. I realized that I was very interested in studying the role of bacteria and protists (microbial eukaryotes) in the marine environment and decided to pursue a graduate degree in marine microbial ecology.
I received a master’s degree from the College of William and Mary (Virginia Institute of Marine Science) in 1999, where I studied heterotrophic bacterial production and utilization of dissolved organic matter. In the fall of 1999, I moved to Los Angeles to begin work on my Ph.D. at the University of Southern California. I am currently studying marine protistan diversity with DNA-based methods to address questions related to how protistan assemblages change over time and how the members of these assemblages interact with one another and their environment.
