Uneven declines between corals and cryptobenthic fish symbionts from multiple disturbances.

Area of Science:

• Marine biology
• Ecology
• Climate change impacts

Background:

• Coral reefs face increasing threats from climate-driven disturbances.
• Mutualistic relationships between coral hosts and symbionts are crucial for reef health.
• Previous assumptions suggested similar impacts on hosts and symbionts.

Purpose of the Study:

• To investigate the differential impacts of climate disturbances on reef-building corals and their symbionts.
• To assess the recovery potential of coral-goby mutualisms under repeated stress.

Main Methods:

• Community surveys of Acropora corals and Gobiodon gobies before and after cyclones (2014-2015) and heatwaves (2016-2017).
• Quantification of changes in coral size and goby group size/occupancy.

Main Results:

• Cyclones caused similar declines (28-30%) in coral size and goby group size.
• Heatwave bleaching led to a 47% decrease in coral size and a significant decline in gobies, with most corals becoming uninhabited (78%).
• All goby species declined, while some coral species persisted.

Conclusions:

• Gobiodon gobies exhibit disproportionately higher declines than Acropora corals following consecutive climate disturbances.
• The inability of gobies to cope with repeated stress jeopardizes their mutualistic role, potentially disrupting ecosystem services.
• Unequal declines highlight the vulnerability of coral reef symbionts and threaten overall ecosystem resilience.