This month we talked with Alexis Pasulka, a Ph.D. research candidate at Scripps Institution of Oceanography.
Alexis is interested in the structure and function of microbial communities. Her research focuses on single-celled eukaryotes, often referred to as protists. These organisms can greatly influence the structure and function of microbial communities through grazing and nutrient recycling. “My goal- said Alexis- is to understand how various sources and scales of heterogeneity (e.g., substrate type, chemical gradients, and biological interactions) structure protistan communities at deep-sea methane seeps.”
Alexis has been working on a methane-seep ecosystem at Hydrate Ridge, Oregon using a combination of molecular and microscopy techniques to determine the community composition, distribution and diversity of protists living in seep sediments and on carbonate rocks.
We asked Alexis a few questions to help us in understanding the hows and whys of her research.
Photo credit: L. Levin, NSF, and WHOI.
1- What are the main implications of these microbial community studies?
This work has implications for understanding the global ocean carbon cycle as well as how organisms make a living under extreme conditions (e.g. dark, low oxygen, high concentrations of toxic chemicals). In addition, deep-sea ecosystems are home to a diversity of life we have yet to discover; therefore, this work will likely reveal new species.
My research is nested within a larger research project aimed at characterizing the biology, from the microbes to the metazoans (e.g. clams and tubeworms), associated with methane seeps. In order to understand seep food-web dynamics, energy flow and the overall ecology of these unique habitats, we must study the entire community. Single-celled eukaryotes are one of the more understudied components of seep communities, but are likely important players within these ecosystems.
By characterizing not only which microbes and animals inhabit seeps, but also how they are making a living (e.g. who’s eating who, who’s living in association with whom), we can gain insight into seep food-webs and methane cycling. This will ultimately give us a better understanding of the fate of methane-derived production in the ocean, an important piece of the global ocean carbon cycle.
2- Is the study of the ecosystem at Hydrate Ridge, Oregon, extrapolative to other deep-see methane seeps?
Yes and no. Not all methane seeps are the same. The source of methane and rate of supply can vary as well as the location of the seep in relationship to other geological features such as faults. In addition, there are many other environmental factors that influence seep communities.
We can learn a lot about different organisms, food-web interactions and metabolic processes from studying them at one seep environment; however, because all of the factors mentioned above influence the patterns we observe, it’s difficult to say these same processes occur at all methane seeps.
That being said, we do find commonalities between seeps. Therefore, the more sites we can visit, the more we can understand the mechanisms responsible for structuring these ecosystems and the more we can then extrapolate the patterns we observe at one seep to others under similar environmental conditions.
3- What is the best part of the work you do – the part that gives you the most satisfaction?
I love going into the field and collecting samples. Using submersibles, such as Alvin, to explore and actually visit a part of the planet that so few people have seen is a dream come true. And of course working within a collaborative group of scientists makes the research fun and exciting.
4- Has funding been a limitation furthering your research? What would you do if you had unlimited amount of research funding and resources?
I think every scientist can always do more with increased funding. Accessing different parts of the deep sea is not a trivial matter. It not only takes a large collaborative effort to plan a successful scientific expedition, but it is also a very expensive endeavor. If I had unlimited funding, I would definitely visit more seep sites. This would enable me to make more comparisons across seeps and begin to address questions about connectivity among deep-sea seeps. In addition, there are many deep-sea ecosystems including seeps that have yet to be discovered. In fact, I was recently on a cruise in which we discovered a new seep off the coast of San Diego (http://scrippsnews.ucsd.edu/Releases/?releaseID=1280). With unlimited funding, you can only imagine what we could discover.
Data analysis is, of course, also costly. When we get back to shore we do a variety of chemical and molecular analyses on our samples. I would not necessarily say that funding has limited my dissertation work, but I could certainly put unlimited research money to good use. The analysis on many of my deep-sea samples was actually only possible because of various small grants and awards that I have received over the past couple of years. These include a Sigma-Xi Grant-in-Aid of Research, an endowed fellowship at Scripps and the P.E.O. Scholar Award.
5- How have MO BIO’s products helped you carry out your work?
The MO BIO kits, especially the soil extraction kits, have made my life much easier. These kits have provided an effective and consistent way to extract DNA from my sediment and rock samples. The clean-up kits (PCR and DNA) have also been incredibly useful for my work.