Tracking fish throughout their life cycle has improved tremendously over the past decades thanks to advancements in isotope chemistry and natural fish tags. Jennifer Granneman studies the otiliths (ear bones) of fish to see if their exposure to pollutants like oil occurred following the Deepwater Horizon spill. Jen is a PhD student at the University of South Florida-College of Marine Science, and is the C-IMAGE Student of the Month for November.

We asked Jen several questions about her past academic career and path into her PhD research, and here experience using lasers.

What is your research focused on, how will your results contribute to improve understanding of impacts of oil spills? What stage of research are you currently in?

As part of my dissertation work, I am using otolith microchemistry to determine whether several offshore fish species in the Gulf of Mexico (GOM) were exposed to the Deepwater Horizon (DWH) oil spill.  Otoliths are aragonite stones located in the ears of fish that record both fish age and ambient water chemistry throughout the lifetime of the fish.  My project utilizes the ability of fish otoliths to record the environmental conditions that a fish has been exposed to throughout its lifetime to assess the exposure of individual fish to the DWH oil spill.  One of the benefits of measuring otolith microchemistry is that we can establish baseline ambient water conditions that a fish was exposed to prior to the DWH oil disaster. 

Thus, using otolith microchemistry to assess oil exposure would be particularly useful in systems with limited pre-spill data on fish health.  This research will help us to determine the health of offshore GOM fish prior to the oil spill.  In addition, this research will help us to determine whether this technique could be successfully implemented in the future to assess oil spill effects on fish populations.  I am currently working on a manuscript to disseminate the results of this research project.

What path did you take to make it to where you are now? Bachelors degree, internship experience, working experience?

I received my B.S. in marine biology at California State University, Long Beach in 2008.  One of the turning points in my education as a future scientist occurred when I attended a semester in the field on Santa Catalina Island off the coast of Southern California.  During this experience, I was able to apply the theoretical concepts I had learned in the classroom to develop my first independent research project investigating the influence of epibiosis and size of wavy turban snails on predator preference.  During my time as an undergraduate student, I had the opportunity to complete several independent research projects and each of those projects presented its own unique learning opportunities.  For instance, I learned how to work efficiently towards a deadline while completing research in Belize, Alaska, and Catalina Island.   I received my M.S. in marine biology at California State University, Northridge.  For my master's thesis project, I evaluated fish production on artificial and natural reefs off the coast of southern California.  After the completion of my master's degree, I moved to Ann Arbor, Michigan, to work as a field technician for the US Geological Survey (USGS).  During my experience at the USGS I learned how to use ArcGIS to create hydrological mixing models of Great Lakes river mouth zones and conducted sampling of the hydrology, larval fish, and benthic invertebrate communities in these areas.  After approximately 2 years at the USGS, I decided to pursue a PhD and I am currently a PhD student in the Marine Resource Assessment program at the University of South Florida, College of Marine Science.

What initially interested you in studying the isotope chemistry?

While working at the US Geological Survey, I listened to scientists discussing the use of otolith microchemistry data to track fish movement throughout the lakes.  This concept intrigued me and prompted me to pursue a PhD in research that could address the extent of water pollution (e.g. oil spills) and fish movement through the use of otolith microchemistry. 

What research tasks are you doing today? 

Today I am working on writing the results section of my research project on otolith microchemistry (described above).  I am excited that I will soon be able to share my research results with the scientific community!  Additionally, I am studying for my oral comprehensive exam, which is scheduled to take place next week.  We analyzed otoliths from the following fish species collected from 2011 to 2013 in the GOM: Red Snapper, Red Grouper, Yellowedge Grouper, Southern Hake, and Tilefish. Otoliths were analyzed using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for a suite of 9 analytes found in DWH crude oil: 24Mg, 51V, 53Cr, 57Fe, 59Co, 60Ni, 63Cu, 64Zn, and 208Pb, with 43Ca used as an internal standard.