Climate change transforms the functional identity of Mediterranean coralligenous assemblages

Area of Science:

• Marine Ecology
• Ecosystem Functioning
• Climate Change Impacts

Background:

• Understanding how disturbances like marine heatwaves (MHWs) impact functional community structure is crucial for predicting ecosystem functioning.
• The effects of MHWs on the functional structure of temperate coral-dominated communities remain poorly understood.

Discussion:

• Long-term data reveal that MHW-impacted Mediterranean coralligenous assemblages exhibit directional changes in functional identity, despite stable functional richness.
• Traits such as large size, long lifespan, arborescent morphology, filter-feeding, and calcified skeletons are declining in MHW-affected areas.
• These declining traits are often supported by a few sensitive, irreplaceable species, particularly habitat-forming octocorals, which disproportionately influence ecosystem functions like 3D-habitat provision.

Key Insights:

• Marine heatwaves drive significant, long-term shifts in the functional identity of temperate coral communities.
• A loss of key functional traits, essential for ecosystem services, is occurring due to MHW impacts.
• Specific species groups, like octocorals, play a critical role in maintaining functional traits and are vulnerable to MHWs.

Outlook:

• Future research should focus on the cascading effects of functional trait loss on Mediterranean coralligenous ecosystems.
• Developing targeted conservation strategies for vulnerable species and functional groups is essential.
• Predicting the long-term consequences of MHWs on biodiversity and ecosystem services is a critical next step.