Corals in Coastal Bays Exhibit Enhanced Resilience to Environmental Stressors
Research indicates that corals in fluctuating coastal bays are more resilient to heat and stress than those in stable reefs.
Corals inhabiting coastal bays with significant environmental fluctuations demonstrate greater resilience to heat and other stressors compared to those in more stable reef environments, according to research by marine biologist Sarah Solomon. Her study provides insights into the mechanisms and trade-offs associated with coral reef resilience amid climate change. Solomon is set to defend her PhD thesis at the University of Amsterdam on Thursday, February 19.
Coral reefs, covering less than 0.1% of the ocean's surface, serve as habitats for approximately 32% of all known marine species. Despite their ecological importance, these reefs are rapidly declining due to climate change and human activities such as pollution and nutrient runoff. Solomon notes that increasing ocean temperatures and more frequent marine heatwaves are leading to widespread coral bleaching and mortality.
To explore coral adaptation to stressful conditions, Solomon studied corals in Curaçao's coastal bays, characterized by warmer waters and greater daily fluctuations in temperature, pH, and oxygen levels, as well as stronger human influence. These bays, often overlooked in coral research, offer valuable insights into coral resilience under future ocean conditions.
In these extreme environments, certain coral species exhibit remarkable survival capabilities. Solomon attributes this to their flexible nutritional strategies, symbiosis with heat-tolerant algae, and hosting of microbial communities that may enhance stress resistance. She explains that corals adjust their feeding methods between autotrophy and heterotrophy in response to changing conditions, such as seasonal variations.
Solomon's experiments involved transplanting corals between bays and reefs and exposing them to heat stress. Reef-originating corals acclimated to harsher bay conditions, maintaining survival and growth, but at the cost of increased energy expenditure and reduced overall health. Conversely, bay-native corals, specialized to their environment, exhibited diminished growth when moved to more stable reefs. Additionally, bay corals showed natural heat resistance, while some reef species increased their heat tolerance after exposure to extreme bay conditions. Solomon notes that certain species can enhance their heat tolerance within a year, though this capacity varies and has clear limits.
Solomon concludes that extreme environments provide valuable insights into coral resilience and adaptive capacity. Naturally climate-change-resistant corals have potential to support proactive restoration initiatives focused on increasing reef resilience. She suggests that some bays could function as nurseries where corals are temporarily 'trained' to cope with higher temperatures before being used in the restoration of degraded reefs. However, she emphasizes that this is not a long-term solution, warning that even the most stress-resistant corals have their limits, and without reducing climate change and pollution, they too will eventually disappear.
Solomon's thesis, titled 'Extreme reef environments as natural laboratories - mechanisms underlying coral acclimatization to future ocean conditions,' is supervised by Professors J. Huisman and M.J.A. Vermeij, with co-supervisors Dr. V. Schoepf and Dr. J.M. de Goeij. The defense is scheduled for Thursday, February 19, from 13:00 to 14:30 at the Agnietenkapel in Amsterdam.