By Yasi Bahmanabadi
With her extensive New College research, May 2021 graduate Isabella McDonnell made new discoveries about Florida manatees—ones that will help inform scientific work on marine mammals in an ever-changing climate.
Her research began during her first year as a marine biology and environmental studies student, when McDonnell had the opportunity to observe two Florida manatees (Trichechus manatus latirostris), nicknamed Hugh and Buffett, in their habitat at Mote Marine Laboratory & Aquarium in Sarasota. McDonnell created an ethogram of the manatees’ swimming patterns, and her findings evolved into the basis for an Independent Study Project (ISP) and, later, a thesis at New College.
“I had opportunities to research manatee vibrissae [whiskers] for credit before even starting my thesis,” said McDonnell, who is currently an aspiring marine mammal rehabilitation specialist. “Being close with my professors allowed me to ask unlimited questions, where they often had knowledge from past research or connections to help me explore specific topics.”
What fascinated McDonnell so much about manatees?
“Florida manatees possess overly sensitive vibrissae across the surface of their bodies,” McDonnell said. “These structures enable manatees to detect water flow and the changes in water flow that may result from the presence of nearby objects (such as other manatees).”
For her undergraduate thesis, entitled Growth Patterns and the Effect of pH on the Florida Manatee (Trichechus manatus latirostris) Vibrissae, McDonnell examined the rate at which manatee vibrissae grow based on the pH levels (and other variable factors) in ocean water. pH and growth were two different aspects of the study (growth was studied at Mote and pH was altered in the lab on trimmed hairs). McDonnell conducted self-led lab research, examining the vibrissae growth rate and what possible effects a changing environment (and an increase in acidity in water over time) may have on the structures.
“I monitored 40 vibrissae follicles on two Florida manatees living in human care over 10 weeks, and experimentally manipulated pH levels in tanks that contained trimmed vibrissae,” McDonnell explained.
To analyze the possible effects of ocean acidification, McDonnell trimmed and soaked the vibrissae in water with a pH similar to that of the ocean’s current pH (as well as in tanks containing water with lower pH), to simulate the level at which ocean pH could be in the near future).
“Future research to understand if these physical changes in the vibrissae alter the functionality of their hydrodynamic sense would help predict the impact that ocean acidification may have on Florida manatees,” McDonnell said. “The most rewarding aspect of this project was investigating information that was thus far unknown. The results I got are truly one-of-a-kind and hopefully a step to even more scientific discovery.”
And studying manatee vibrissae was just one component of McDonnell’s Florida-based marine research at New College. She also observed the effects of toxins from a species of algae on marine mammals. Florida red tide, caused by the microscopic algae Karenia brevis, is a type of harmful algae bloom that affects Florida’s southwest coast nearly every year. Presently, a patchy bloom of Florida red tide is persisting offshore and inshore along several Southwest Florida counties.
Florida red tide cells produce a toxin called brevetoxin that can cause mortalities in marine mammals, fish and invertebrates (as well as respiratory irritation in humans at the beach). Different marine animals can accumulate brevetoxin through multiple methods. Fish take in brevetoxin present in the water through their gills. Manatees can inhale brevetoxin that has aerosolized at the water’s surface or ingest brevetoxins that have settled onto their favorite food: seagrass. Other marine mammals, such as dolphins, inhale brevetoxin at the water’s surface, but they also accumulate toxins rapidly by eating contaminated fish through biomagnification.
“Because of biomagnification, even the largest of marine animals can be affected by the microscopic toxin,” McDonnell said. “During widespread blooms of Florida red tide, hundreds of thousands of animals and people can be affected.”
During her time at New College, McDonnell compiled information from past Florida red tide data, and conducted toxin research on marine mammals to find possible connections between past Florida red tide events and environmental change. She collaborated closely with Jayne Gardiner, Ph.D., the director of the Pritzker Marine Biology Research Center and an associate professor of biology; and Athena Rycyk, Ph.D., an assistant professor of biology and marine science at New College.
“My ultimate career goal is to work on mitigating the effects of climate change and other human impacts on marine life, specifically mammals,” McDonnell said. “Working with experts in the field I’m so passionate about gave me access to information and opportunities I would never have gotten anywhere else but at New College.”
Yasi Bahmanabadi is an intern in the Office of Communications & Marketing.