Dataset: Dataset 2: Lab incubations of mussels in 2022 to examine the influence of simulated abrasion of periostracum on external shell dissolution collected at Marshall Gulch Beach, CA from August 2021 to March 2022

We performed dissolution assays to explore how the coarseness of sand grit used to simulate abrasive removal of the periostracum might modify rates of dissolution of underlying shell. As in the first set of trials, individual California mussel valves were placed into individual incubation bottles, and shell loss was determined using the alkalinity anomaly method based on measured increases in seawater TA described above. Seawater conditions were modified following methods of chemical addition (described above) and reduced seawater pH (pH = 7.4) without changing seawater TA. Mussels were collected and sacrificed in a similar way to Dataset 1; following sacrifice, the interior surface of the mussel valves were coated with silicone to prevent interior shell dissolution signal.

Mussel valve preparation: To prepare mussel valves for the incubation, shell periostracum was abraded using sanding sponges (Gator brand) of two levels of grit coarseness (P50-60: coarse (n = 11), and P120-150: fine (n = 12)). We included control mussel valves (15% of daily sample size), collected with no periostracum cover, to compare dissolution rates between abraded and periostracum that was removed naturally in the field.