During the past four decades, the Hawaiian monk seal has become one of the most endangered species in the world—their demise believed to be the result of environmental and anthropogenic forces.
Solving the mystery behind the seals’ disappearance and uncovering correlating information about oceanic productivity are the goals of research being conducted by Amy Hirons, Ph.D., assistant professor at NSU.
Biology and marine biology students assisted with the research, including two recent NSU graduates: Joseph Deek (B.S. in Biology, 2014), and Mikaela Edwards (B.S. in Marine Biology, 2014). Marine biology major Courtney Cenkner will continue the work begun by Deek and Edwards.
The students received an honorable mention for their work at NSU's 2014 Undergraduate Student Symposium.
Their project, “Hawaiian Monk Seals—Record of Environmental Influence in an Endangered Species,” is supported by a President’s Faculty Research and Development Grant.
With fewer than 1,300 Hawaiian monk seals left in the world, Hirons hopes the data will offer insight into why the marine mammals are dying at a rapid rate—especially juveniles—while also revealing important clues about environmental and oceanic changes.
“Hawaiian monk seals have been in a steady decline for more than 40 years. They are recognized as the most endangered seal within U.S. waters,” said Hirons, a biological oceanographer who serves as the chair of the college’s marine biology major.
A chemical analysis of teeth and bone samples taken from deceased seals is helping Hirons and the students profile changes affecting the seals’ survival and develop a timeframe of environmental fluctuations and ecosystem changes.
Edwards participated in the research as part of an independent study course with Hirons. She plans to pursue a master’s degree in marine science at NSU’s Oceanographic Center.
Deek contributed to the project as a pre-dental student and gained research experience while sharpening his manual dexterity skills.
“I’ve always been interested in research,” said Deek, who plans to attend NSU’s College of Dental Medicine. “Dr. Hirons had these teeth samples from the deceased seals. Knowing how that tied in with my future, working with her seemed like a perfect match.
“I could hone in on my manual dexterity skills, get situated in a laboratory environment, and learn how to be a scientist. The early work reviewing the literature also was helpful with my other classes, and the journals helped with scientific comprehension and tied into the biochemical classes I was taking,” said Deek, who was a member of NSU's Undergraduate Honors Program and NSU's Dual Admission Program in dental medicine.
At the lab at NSU’s Oceanographic Center, Deek sectioned each tooth into two halves and produced a very thin section of the middle of the tooth—striking a delicate balance to collect data while not damaging the tooth.
“We’re using the growth layers in the teeth to determine how old the seals were at the time of death,” Deek said. “There has been a lot of varying data about whether the decreasing population is due to a loss of habitat or overfishing. By looking at the age of the teeth and oceanographic elements, we’re trying to piece together why.”
The teeth and bone samples were collected from seals located in the Northwest Hawaiian Island chain and main Hawaiian Islands and represent more than 225 deceased Hawaiian monk seals from the last 40 years. More than 200 canine teeth ranging from about one to three inches long are being sectioned and the growth layers counted to determine the ages of the seals. Collagen was extracted from 220 bone samples.
Stable isotope ratios are collected from both the teeth and bone collagen, and the data is being used to reconstruct possible changes over time in the seals’ diet, loss of prey species, or ecosystem changes.
“We are using these mammals as a means of studying year-to-year ocean productivity and as a tool to provide information about long-term environmental changes, such as ocean temperatures or salinity levels,” Hirons said.
“If we alter the productivity of the oceans, we are ultimately impacting humans. Is it something that humans are doing that is causing the population decline, or is it part of a natural cycle?
“Environmental changes, especially changes in sea surface temperatures, affect not only the seals but also the food web. Population decreases during the 1980s and 1990s have been linked to the decrease of prey species.”
For the students, “it was rewarding to see how far we came from the initial idea,” Deek said.
“Participating in a study such as this has driven me toward the continuation of my education in the hopes of working in conservation,” Edwards said. “Dr. Hirons has always been a fantastic mentor and has taught me so much throughout my undergraduate career. The experience I gained working in the lab and presenting with her and my classmates has helped me grow as a future researcher.”