Ocean acidification and temperature increase impact mussel shell shape and thickness: problematic for protection?

Area of Science:

• Marine Biology
• Oceanography
• Ecology

Background:

• Ocean acidification poses a threat to marine calcifying organisms, including mussels.
• Elevated temperatures exacerbate the negative impacts of ocean acidification on shell formation.

Purpose of the Study:

• To investigate the combined effects of ocean acidification and increased temperature on the shell formation of the edible mussel, Mytilus edulis.
• To assess the functional implications of altered shell morphology for protection under changing environmental conditions.

Main Methods:

• Mussels (Mytilus edulis) were cultured for 9 months under varying pCO2 levels (380–1000 µatm) and temperatures (+2°C).
• Shell growth, thickness, aragonite layer thickness, and shell shape were analyzed.
• Shell thickness index and shape analysis were used to quantify changes.

Main Results:

• Ocean acidification significantly reduced shell aragonite thickness and shell thickness index.
• Mussel shells exhibited altered shapes under elevated pCO2 conditions (750 and 1000 µatm).
• Shells became rounder and flatter with thinner aragonite layers, potentially increasing vulnerability.

Conclusions:

• Ocean acidification impairs the ability of Mytilus edulis to form robust shells.
• Changes in shell shape may represent a compensatory mechanism for protection.
• Further research is needed to understand the long-term implications for mussel populations and marine ecosystems.