Getting a head start: Influential early experiences for juvenile corals and community college science students
Coral reef resilience to ocean warming and recovery after high-mortality disturbances relies heavily on successful recruitment and survival of stony corals. Due to their small size and cryptic nature, the response of juvenile corals to thermal stress is far less understood than that of conspecific adults. Newly settled coral recruits are at high risk for mortality and are vulnerable to environmental stress due to their small size. I explored the influence of early life experiences on the survival of juvenile corals in thermal stress by investigating whether (1) heterotrophic nutrition and (2) tissue fusion promote survival during thermal stress by increasing in tissue growth and colony size, allowing juveniles to overcome size-dependent risk of mortality. I first exposed newly settled Pocillopora acuta (N=716) to nutritional treatments for short (1-month) and extended (1-year) periods then exposed these juveniles to an elevated temperature stress. To track physiological responses to nutritional treatments, I developed a non-destructive methodology using laser-scanning confocal microscopy to measure tissue thickness and symbiont fluorescence in live juvenile colonies allowing for repeated measures of individuals. Heterotrophic feeding was necessary to maintain tissue growth for juvenile corals and increased survival by 28% in thermal stress. Tissue fusion with neighboring recruits provides an additional pathway to rapidly increase colony size faster than by growth alone. Fusion between juvenile colonies provides an opportunity for increased genetic diversity within individual colonies because self-recognition systems do not develop until several months after settlement. To investigate the role of genetic diversity and colony size in promoting survival in thermal stress, I manipulated the genotypic richness (1-4 genotypes) and number of juveniles (1-4 juveniles) involved in tissue fusion (N=221). Tissue fusion between juvenile P. acuta corals provided a strong survival advantage in high temperature, delaying mortality by 5 days. Within these fused colonies, genetically diverse fusions survived 1.5 days longer in thermal stress, which may be due to a “rescue” effect provided by more thermally tolerant genotypes. As oceans continue to warm, these “head start” experiences may become increasingly important in supporting the survival of fast-growing, brooding corals, which are often the first corals to recruit and seed reefs following mortality events. For science students early in their education, involvement in scientific research can also provide a “head start” opportunity as they navigate through the “leaky pipeline” in their pursuit of a science career. I involved five community college students in my research of coral biology and used qualitative methods to understand the impacts of this experience on their career trajectories. Over the course of a one-year study, students reported increases in their knowledge and understanding of science but remained uncertain of their professional science identity. To support student persistence in science, research internships should integrate career exploration with practice in research and should continue to develop stronger integration between scientific and educational research.