Shell dissolution rates differ fourfold between mussel species

Area of Science:

• Marine Biology
• Oceanography
• Climate Change Science

Background:

• Ocean acidification threatens marine calcifiers, especially bivalves in the California Current System.
• Mussels like *Mytilus californianus* and *M. trossulus* have distinct habitat preferences regarding salinity.

Purpose of the Study:

• To determine abiotic shell dissolution rates of mussel congeners under varying ocean acidification conditions.
• To quantify the contribution of shell interior versus exterior surfaces to dissolution.
• To predict climate change impacts on coastal bivalve populations.

Main Methods:

• Experimental analysis of shell dissolution rates across a range of pH (6.5-9.3) and aragonite saturation states (0.1-9.0).
• Comparison of dissolution between *Mytilus californianus* and *Mytilus trossulus*.
• Experimental sealing of shell interiors to assess the role of internal dissolution.

Main Results:

• *Mytilus trossulus* exhibited fourfold higher shell dissolution rates compared to *Mytilus californianus*.
• Sealing the shell interior significantly reduced dissolution rates in both species, highlighting internal dissolution.
• Dissolution rates varied significantly between mussel congeners.

Conclusions:

• Abiotic shell dissolution is a significant factor for mussel survival under ocean acidification.
• The freshwater-tolerant species *M. trossulus* is more vulnerable to dissolution, with implications for low-salinity environments.
• Differential dissolution rates between congeners can alter future intertidal population structures.