Ocean acidification bends the mermaid's wineglass

Area of Science:

• Marine Biology
• Biomechanical Engineering
• Oceanography

Background:

• Ocean acidification reduces calcium carbonate saturation, impairing calcified structures in marine organisms.
• Calcified structures are crucial for organismal defense, resource acquisition, and dispersal.

Purpose of the Study:

• To investigate the impact of ocean acidification on the mechanical performance of the green alga Acetabularia acetabulum.
• To test if decreased calcification compromises skeletal integrity under elevated CO₂ conditions.

Main Methods:

• Utilized cantilever beam theory to assess mechanical properties.
• Examined Acetabularia acetabulum along a natural CO₂ gradient from volcanic seeps.
• Quantified calcification, stiffness, and droopiness of algal structures.

Main Results:

• Calcification and mechanical properties declined significantly with decreasing calcium carbonate saturation.
• Algae at 2283 µatm CO₂ showed 32% less calcification, 40% less stiffness, and 40% increased droopiness.
• Stem stiffness decreased exponentially with reduced calcification, indicating a non-linear relationship.

Conclusions:

• Decreased calcification substantially impairs the mechanical performance of Acetabularia acetabulum.
• Subtle changes in calcification can lead to dramatic alterations in skeletal performance under ocean acidification.
• Altered skeletal performance may significantly influence critical biotic and abiotic interactions for marine calcifiers.