Thermal and Acidification Gradients Reveal Tolerance Thresholds in Pocillopora acuta Recruits

Area of Science:

• Marine Biology
• Coral Reef Ecology
• Climate Change Science

Background:

• Coral reefs face significant threats from ocean warming and acidification.
• Organismal stress tolerance is dependent on life stage and environmental variability.
• Kāne'ohe Bay, Hawai'i, experiences natural diurnal fluctuations in temperature and pH.

Purpose of the Study:

• To assess the early life stage tolerance of Pocillopora acuta to projected ocean warming and acidification.
• To investigate the ecological, physiological, biomineralization, and molecular responses of coral larvae and recruits.
• To understand the impact of environmental variability on coral resilience.

Main Methods:

• Exposed Pocillopora acuta larvae to Control, Mid, and High ocean warming and acidification scenarios for six days.
• Measured survival, settlement, calcification, skeletal deposition patterns, and gene expression.
• Analyzed transcriptomic responses, including metabolism and DNA damage repair.

Main Results:

• Pocillopora acuta early life stages survived and settled under all tested conditions.
• High conditions significantly reduced survival and settlement, altering skeletal deposition.
• Transcriptomic analysis revealed depressed metabolism, reduced ATP production, and increased DNA damage repair under High conditions.

Conclusions:

• Coral juveniles in Kāne'ohe Bay can tolerate moderate projected ocean warming and acidification.
• Severe conditions negatively impact coral cellular metabolism, survival, and recruitment.
• These findings highlight the vulnerability of coral reefs to future climate change scenarios.