A recent study from USC Dornsife It has revealed some unexpected details about the effects of global warming on coral reefs. According to the research, the adaptations of a common Caribbean coral could have significant implications for our approach to protecting these important marine ecosystems.
Mountain star coral
The study focused on Orpicella faviolata, a mountain star coral commonly found in the Caribbean Sea. The goal was to determine whether coral populations that tolerate increased temperatures can pass this heat resistance on to their offspring.
„Orbicella faviolata, commonly known as mountain star coral, is a dominant reef-building species in the Caribbean, but since the 1980s, populations have suffered severe declines due to repeated bleaching and disease-driven mortality,” the researchers wrote.
„Previous research has shown that coastal adult O. favolata populations in the Florida Keys can maintain more coral cover and recover from bleaching faster than their marine counterparts. However, it is unclear whether this origin-specific variation in thermal resistance is heritable.
Heat resistant corals
A popular hypothesis among scientists is that heat-tolerant coral parents will produce offspring with similar adaptations for heat resistance.
However, Professor Carly Kenkel and her team discovered a paradox. They found that the offspring of the less heat-acclimated population showed better resilience when subjected to high temperatures compared to heat-tolerant lineages.
„The study results have significant implications for how we think about saving coral reefs,” said Professor Kenkel. „It’s not as simple as breeding more heat-tolerant corals.”
How the study was conducted
For the investigation, the scientists collected gametes (reproductive cells) from coral reefs at two distinct sites in the Florida Keys. They then hybridized the corals under controlled conditions and exposed the larvae to elevated temperatures.
The team also analyzed the genomes of these corals to detect signs of stress under elevated temperature conditions.
Study limits
The results of the study suggest that the heat tolerance of coral offspring may be determined by various factors. This includes the frequency with which their parent corals are bleached or face other environmental challenges.
However, it should be noted that this research focused on one coral species. Other coral species may respond differently, and the controlled laboratory setting of the study did not capture the myriad factors that affect corals in natural habitats.
Future research
The scientists plan to delve deeper into coral adaptation mechanisms, considering their historical experiences and interactions with other species and the overall health of the reef system.
Professor Kenkel noted that coral recovery may require a more comprehensive approach. „Instead of focusing only on breeding corals that are more heat tolerant, we need to consider other factors that affect coral survival and multifaceted interventions.”
Research implications
„The documented resilience of mature corals to continuous thermal stress and bleaching in environments with high and variable temperatures may come with highly consequential trade-offs,” the researchers wrote.
„In this study, we show that larvae from a site that routinely experiences and recovers from heat-induced bleaching are significantly underperformed compared to larvae from a cooler, less variable reef site.”
„The unexpected result that highly heat-tolerant O. faviolata produced poorer quality offspring challenges the prevailing paradigm that breeding susceptible populations with heat-tolerant individuals can contribute to genetic recovery.”
The study is published in the journal Global Change Biology.
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