A study led by student scientists at the University of Hawai‘i (UH) at Mānoa showed that subjecting rice coral larvae to warmer temperatures did not enhance survival once the coral grew into juveniles and had to endure heat stress. The study recently appeared in the journal Coral Reefs.
Climate change-triggered ocean warming has redesigned reef ecosystems as coral bleaching events carry on leading to large coral die-offs worldwide. Coral restoration endeavors in Hawai‘i are massive and include selectively breeding more resilient coral, vigorous management of susceptible areas and outplanting coral nurtured in a laboratory.
Ariana Huffmyer and Shayle Matsuda, former marine biology graduate students in the Mānoa School of Ocean and Earth Science and Technology (SOEST) at UH, were on an assignment to enhance efforts to restore corals.
Matsuda met Gyasi Alexander, an undergraduate student at the University of Rhode Island, at the Inclusive Science Communication Symposium and invited him to join the summer internship at the Hawai‘i Institute of Marine Biology (HIMB) in SOEST.
Making the Most of Restoration Efforts
The team’s method began with gametes gathered during large spawning events and nurturing them to the larval stage, with the extended goal of establishing more coral on the reef.
Although this process can provide more genetic diversity to the reef than fragmentation practices alone, it takes considerable time, effort and capital, and the downstream survival of the corals may be impacted by ocean warming events.
Shayle Matsuda, Postdoctoral Fellow, Shedd Aquarium
“With this study, we wanted to test whether exposing larvae to different temperatures would both increase larval survival and settlement, and importantly, if exposure to elevated temperatures as larvae would lead to increased thermal tolerance, that is, higher survival, at the juvenile stage,” Shayle Matsuda added.
“However, we do not have a good understanding of the degree, time, and profile of stress required to produce positive carry over effects and, if the effects are produced, how long they last,” added Huffmyer, currently at the University of Rhode Island.
Throughout the course of their experiments, the scientists, including HIMB coral ecologist Josh Hancock, learned that increasing temperature to mimic future ocean warming did not enhance larval survival and did not better the survival after larvae developed on the ocean floor. Instead, their findings recommend that nurturing rice coral at ambient temperatures heightens early life stage survival.
As climate change intensifies, it is critical that we focus our restoration and conservation strategies that will have the greatest positive impact. Since we found that thermal conditioning did not provide positive benefits for thermal tolerance in recruits in this species, we suggest that our time and resources are best spent pursuing other avenues of thermal conditioning and further testing thermal conditioning scenarios that may produce positive impacts.
Ariana Huffmyer, Former Marine Biology Graduate Student, Mānoa School of Ocean and Earth Science and Technology (SOEST), UH
Impact of Hands-On Research Experience
Prior to this experience, I hadn’t really known what it felt like to think like a scientist. The idea of research was definitely intimidating. Ariana and Shayle helped me immensely by encouraging me to share the observations and questions that I had, even when I was afraid to use my voice.
Gyasi Alexander, Undergraduate Student, University of Rhode Island
“That comfortability helped me to realize that thinking like a scientist, feeling like a scientist is really just pursuing the curiosity you feel behind what you see and take in, especially when you don’t have all the answers right away,” Gyasi Alexander added.
After finishing the summer internship at HIMB, Alexander has a vivid path for his own graduate school interests.
“My current goal is to develop a skillset in big data,” said Alexander. “I reflected on my work on HIMB and realized how much more effective I could have been if I had a more robust set of data analysis skills. So among my next moves, I plan to learn a few programming languages like R and Python to aid my work in the future and make myself available to even more opportunities.”
Alexander, G., et al. (2022) Larval thermal conditioning does not improve post-settlement thermal tolerance in the dominant reef-building coral, Montipora capitata. Coral Reefs. doi.org/10.1007/s00338-022-02234-x.