Stress-Resistant Symbiodiniaceae and Diverse Bacterial Communities Promote Coral Persistence in Variable,...

Area of Science:

• Marine Biology
• Symbiosis Research
• Coral Reef Ecology

Background:

• Coral holobionts, comprising corals and their associated microbial communities (Symbiodiniaceae and bacteria), face increasing global and local stressors.
• The role of these microbial partners in coral persistence within variable, extreme, multi-stressor environments remains incompletely understood.
• Semi-enclosed inland bays serve as natural laboratories for studying coral holobiont responses to future ocean conditions.

Purpose of the Study:

• To investigate the influence of Symbiodiniaceae and bacterial communities on the persistence of Caribbean coral holobionts across different habitats and seasons.
• To assess how environmental variability in inland bays impacts coral holobiont composition and function.
• To understand the adaptive strategies of coral holobionts in multi-stressor environments.

Main Methods:

• Sampling of three Caribbean coral species (Siderastrea siderea, Siderastrea radians, and branching Porites sp.) from inland bays and fringing reefs in Curaçao.
• Seasonal sampling across dry and wet periods to capture temporal variations.
• Analysis of Symbiodiniaceae and bacterial community composition in relation to environmental conditions.

Main Results:

• Coral species in inland bays consistently hosted high proportions of stress-tolerant Symbiodiniaceae, suggesting a role in host survival.
• Distinct bacterial community compositions were observed across habitats, sites, and seasons for Siderastrea siderea and Siderastrea radians.
• Bacterial communities in these species exhibited higher proportions of bacteria involved in sulfur and nitrogen cycling in inland bays and during wet seasons, indicating enhanced metabolic flexibility.

Conclusions:

• Stress-tolerant Symbiodiniaceae and metabolically flexible bacterial communities are crucial for Caribbean coral holobiont persistence in challenging, multi-stressor environments.
• Environmental conditions significantly shape coral-associated bacterial communities, highlighting their adaptive potential.
• These findings provide insights into coral holobiont resilience mechanisms relevant to ongoing climate change and intensifying ocean stressors.