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The Ways of Water: My Life-Changing Aquatics Externships

By Michelle Greenfield, Cornell DVM ‘23

I started veterinary school with the goal of working with stingrays, dolphins, and fish. Now, four years later, I can say I have worked at some of the top aquariums and other aquatic facilities in the country and connected with colleagues who are leading this field.

This past spring, I had the pleasure of completing two aquatic veterinary externships thanks to the generous support of the Cornell Yang Center for Wildlife Health Student Support Fund. In March, I worked with Drs. Roy Yanong and Debbie Pouder at the University of Florida Tropical Aquaculture Laboratory (TAL) in Ruskin, Florida. In April, I worked with Drs. Greg Scott, Greg Walth, Sarah Miller, Ashley Kirby, and Tonya Clauss at the Georgia Aquarium in Atlanta, Georgia. These two valuable experiences exposed me to the breadth of the field of aquatic veterinary medicine.

Learning Fish Diagnostics at the University of Florida Tropical Aquaculture Laboratory

Fish parasite shown through a microscope
Dactylogyrid, a common freshwater fish parasite.

At TAL, I learned the ins and outs of fish diagnostics. I learned how to take a skin scrape (gently running a slide cover across the fish’s skin to pick up things on the external surface) and examine it under the microscope for parasites, how to identify common bacterial and viral pathogens affecting fish, and honed my ability to ask clients pertinent questions to help diagnose sick or dying fish. I completed necropsies (postmortem examinations) and helped decipher the underlying pathology in fish submitted to the lab.

And perhaps most importantly, I gained a greater understanding of water quality parameters and how changes in these parameters directly affect the health of the animals. Poor water quality is one of the most common causes of fish mortality, and having a solid grasp of how even the most subtle changes in parameters such as temperature, alkalinity, ammonia, and nitrite level can affect fish is critical for a career in this field.

Michelle Greenfield at the Tropical Aquaculture Laboratory with Dr. Roy Yanong and fellow aquatic veterinary extern Lee Gedelian.
Great times at the Tropical Aquaculture Laboratory with Dr. Roy Yanong and fellow aquatic veterinary extern Lee Gedelian.

One of the most eye-opening aspects of this externship was going on field trips to nearby aquaculture facilities. Prior to this externship, most of my experience focused on public aquaria and aquaculture within the context of repopulating natural waterways. This was my first foray into ornamental aquaculture systems. Speaking with farmers and the veterinarians at these farms taught me important management practices for maximizing fish reproduction, how to write health certificates, tips for leading a diverse team, and the process for shipping and transporting fish. These visits improved my understanding of the practical challenges of raising fish, and have informed my understanding of where these fish come from and how aquaria source fish. This experience also broadened my awareness of the aquaculture industry, which I will continue to share with my listeners on the Aquadocs Podcast.

Practicing Clinical Skills at the Georgia Aquarium

My externship at Georgia Aquarium helped to refine my clinical thinking skills in the context of aquatic species, and demonstrated the importance of working as a team, being flexible, and keeping detailed records. With over 100,000 individuals spread across 60+ habitats, there were always patients that needed our attention.

Michelle Greenfield with the Georgia Aquarium Animal Health Team
The Georgia Aquarium animal health team.

I worked closely with the animal health team to perform annual exams on sea lions, koi, rays, penguins, belugas, and dolphins, as well as pre-shipment examinations on any animals being sent between facilities. I learned how to monitor the progression of pododermatitis (also called bumblefoot, an infection affecting the skin of the foot) in penguins and wrap their feet to promote healing. I completed full physical exams on fish with presumptive tumors and then developed and enacted treatment protocols for these fish. I also worked with the aquarium’s quarantine facility and learned protocols for quarantining animals between shipments to different facilities to protect the individual’s health and safety and that of the receiving collection.

One of my goals while at Georgia Aquarium was to continue refining my skills with ultrasound. Ultrasound is one of the primary diagnostic tools in aquatic medicine due to its versatility for visualizing an animal’s internal structures. I assisted with reproductive ultrasound exams in rays and dolphins and practiced my technique on fish and belugas. Given how important these skills are, I focused my extern presentation on techniques for dolphin ultrasound and outlined the normal images one would expect at each main location on the dolphin’s body. Developing this presentation helped me hone my skills and helped me develop a foundation for continuing to refine these skills over the years to come.

Michelle, Zach and penguin.
Introducing Zach, my husband, to my new African penguin friend.

In addition to medical care, an important component of animal health and welfare is animal husbandry. I had the privilege of spending time with the penguin animal care team at Georgia Aquarium. (Huge thanks to the penguin team for allowing me to introduce my fiancé Zach - now husband! - to some of my other loves.) As I stuffed vitamins into fish and scrubbed feces off the rocks, I reminisced about my time interning at SANCCOB, the Southern African Foundation for the Conservation of Coastal Birds, in South Africa, during my first summer in college, which is where I first decided to become a veterinarian. I have come a long way since then, but my drive to care for these incredible animals has continued and flourished.

In addition to the medical knowledge gained during these externships, building and maintaining relationships with new colleagues in a professional and social sense has been incredibly meaningful. Establishing connections is what creates a lasting impact. I am truly grateful for the game nights and trivia adventures with colleagues, and for all of the kind folks I met during my externships, especially those who were gracious enough to host me in their homes. These new friendships and skills I gained during my externships will last a lifetime.  

Michelle Greenfield portrait, shown with a captive penguin.

Michelle Greenfield, DVM ‘23, CertAqV is a Cornell University College of Veterinary Medicine graduate and is currently a rotating intern at Oradell Animal Hospital. She is the producer and host of Aquadocs, the #1 podcast on aquatic medicine and a top 50 life sciences podcast. Michelle has a degree in Ecology and Evolutionary Biology from Princeton University and has worked with a number of organizations including the US Navy’s Marine Mammal Program, the Sarasota Dolphin Research Program, Brookfield Zoo, Georgia Aquarium, Hubbs SeaWorld Research Institute, and SANCCOB. Her research interests focus on bottlenose dolphin social behavior as well as innovative methods of science communication.

All images provided by Michelle Greenfield.

Please consider giving to the Cornell Yang Center for Wildlife Health Student Support Fund to help provide more hands-on experiential learning opportunities for students passionate about wildlife health and conservation.
Related projects: Freshwater Fish
Related programs: Aquatic Animals