Coral reefs in the Florida Keys have experienced unprecedented declines over the last 30 years. Hard corals, the backbone of the reef ecosystem, have seen their populations reduced by 44% since 1995. However, the loss of coral is not uniform and it is unclear why some reefs in this system are more resilient to stress than others. For example, reefs closer to shore that are exposed to temperature extremes and pollutants also exhibit higher coral growth and cover than offshore reefs that experience more stable temperatures and better water quality. This project will measure gene activity in corals that were experimentally transplanted between inshore and offshore reef environments. This will help identify the stressors acting at each reef and the mechanisms used by corals to adapt to them. Understanding the physiological mechanisms used by reef-building corals to adapt to local conditions can help refine predictions about how they will respond in time to the effects of global climate change.
Reef-related activities in the Florida Keys generate $3.4 billion in sales and income annually and support 36,000 jobs. Loss of this ecosystem would be devastating both ecologically and economically. The results of this project will advance understanding of the relationship between the environment and the state of the coral reefs. It will also identify mechanisms of coral adaptation, and provide molecular tools to assess coral condition in natural environments which will better inform management practices aimed at conserving this valuable ecosystem. Training of students would occur.
Coral reefs in the Florida Keys have experienced unprecedented declines over the last 30 years. Hard coral populations, the backbone of the reef ecosystem, have declined by 44% since 1995. However, the loss of coral is not uniform and it is unclear why some reefs in this system are more resilient to stress than others. This project investigated molecular mechanisms of coral adaptation to understand variation in coral resilience among different environments. We measured gene expression on the scale of the whole genome in both the coral host and its symbiotic algae in the mustard hill coral Porites astreoides and examined how the activity of the genes corresponds with the ability of the coral to strive in different reef environments and withstand stress. We found that corals from variable (inshore) environments regulate their gene activity more strongly than corals from more stable (offshore) environments. The enhanced capacity for regulation of stress response genes protects these corals from bleaching, but comes at the cost at reduced growth rate when the environment is relatively stable. Understanding such tradeoffs will be important for developing conservation management strategies to protect corals with different temperature tolerances and develop feasible strategies for restoring the reefs that suffered from the effects of climate change.
