Aleksandra Crossman, 22, a recent graduate of Memorial University of Newfoundland in Labrador, Canada, recently completed her second internship at BIOS with support from the Canadian Associates of BIOS (CABIOS). In 2020, during her junior year of college, Crossman participated in a 12-week internship with reef systems ecologist Eric Hochberg. Keen to continue her study of corals, she jumped at the opportunity to conduct another CABIOS internship after completing her bachelor’s degree in marine science. “A CABIOS internship is a fantastic way to acquire hands-on skills and work alongside knowledgeable mentors in the field of ocean sciences,” Crossman said.
In fall 2020, student Aleksandra Crossman spent 12 weeks conducting an internship with BIOS reef systems ecologist Eric Hochberg, supported by a fully-funded scholarship from the Canadian Associates of BIOS (CABIOS). Her project used photomosaics and artificial intelligence to map benthic habitats as part of an environmental assessment carried out for the Bermuda Electric Light Company (BELCO). It proved to be an excellent match and, this winter, Crossman came back to BIOS for a second time for research on coral pigments.
“I wanted to return to BIOS because I love the community, and because I was intent on continuing the research concepts I started working on with Eric,” Crossman said. “Studying coral has always been my goal and I found our original research kept bringing up more and more interesting topics.”
For more than 45 years, CABIOS has offered scholarships for Canadian students, and students enrolled in Canadian colleges and universities, to participate in research internships at BIOS or attend BIOS summer courses. In that time, over 250 students from institutes across Canada have traveled to Bermuda to study and work alongside BIOS faculty and research staff.
Crossman’s research project this year focused on the seasonal changes in coral pigments and what environmental factors, such as water temperature or day length, trigger those changes. To investigate this, Crossman carried out a controlled study that manipulated temperature and light, while taking daily measurements of chlorophyll—a photosynthetic pigment found within the tissues of reef building corals. Chlorophyll, the same pigment found in the leaves of deciduous trees, provides the coral organism with the bulk of its energy requirements.
“I initially applied for a CABIOS scholarship because I wanted to gain experience with new marine species in a different part of the Atlantic Ocean while also learning new research techniques,” said Crossman, who is now 22. “I consider this kind of hands-on experience more valuable to students as it gives us the opportunity to be in a real work environment.”
During the final year of her bachelor’s degree at Memorial University of Newfoundland in Labrador, Canada, Crossman kept in touch with Hochberg to see about potential opportunities to return to the Institute.
In September 2021, Crossman graduated with a degree in marine science. Weeks later, she was offered the opportunity that she and Hochberg had been waiting for: a second CABIOS scholarship for another 12-week research internship. To avoid being away from home over the holidays, the BIOS University Programs department arranged for her internship to begin the first week of February in 2022.
“Alek was fantastic when she was here in 2020: motivated, bright, and a pleasure to work with,” Hochberg said. “I knew she wanted to continue expanding her horizons, and when the opportunity arose, it was an easy decision to bring her back.”
This time, her research focused on the phenology, or seasonal changes, of coral pigments. Corals are animals that have formed a unique symbiotic relationship with a photosynthetic algae called zooxanthellae living within their tissues. In exchange for a safe place to live and nutrients required for photosynthesis, the zooxanthellae provide reef-building corals with energy, in the form of sugars formed during photosynthesis, which provide up to 90 percent of the corals’ energetic needs.
Within these zooxanthellae are pigments, including chlorophyll, the same pigment found in the leaves of trees. Hochberg’s previous interns have used a spectrometer to measure the intensity of light at different wavelengths, or spectra, of corals on a daily basis to see how chlorophyll changes. It turns out that, much like deciduous trees in terrestrial ecosystems, the pigment levels in corals change seasonally as well.
“On land, certain conditions must be met in terms of air temperature and day length before the pigment response in leaves is triggered,” Hochberg said. “It makes sense for corals and zooxanthellae to have evolved this same pattern because they’ve had this symbiosis since before the dinosaur era.”
To investigate further, Hochberg devised a controlled study that involved manipulating temperature and light, then measuring daily changes in chlorophyll. As with previous studies, spectral measurements were taken to get estimates of chlorophyll rather than taking direct tissue samples, which would kill the sample coral organisms used in the investigation.
The study used a total of 20 corals arranged evenly in four tanks that are housed inside Hochberg’s wet lab. One tank was allowed to progress through spring light and temperature conditions as normal. A second tank was allowed to progress with temperature, but not light. The third tank was allowed to progress with light, but not temperature. The fourth tank was not allowed to progress at all. For 30 days, Crossman measured the corals’ spectra, in addition to maintaining the experimental systems, caring for the living corals, and conducting basic data processing. Data analysis is still underway.
“Even though there were some hiccups, this experience taught me problem-solving skills and how to improve my research in the future,” Crossman said. “Nothing is ever perfect the first time you do it, so I’m only encouraged to improve the design and answer the new questions that come up.”
Now back home in Quispamsis, located in New Brunswick, Canada, Crossman is applying for internships and jobs in marine science fields, while also contemplating graduate school, a decision she credits in part to her experiences at BIOS. Crossman says she’s particularly interested in studying coral genomics and the processes behind coral phenology.