The results of linear mixed effects models testing explanatory variables for carbon and oxygen isotopes in Mytilus californianus.

a. δ13C (‰, PDB scale) and b. δ18O (‰, PDB scale) in M. californianus from 1999(or 2000)–2009. The coefficient and AIC are based on a linear mixed effects model where the individual shell was the random effect. Environmental variables were first fit in isolation. The best fit model (bold) to the δ13C data included all 3 significant variables: UI for the year, pH and atmospheric CO2. Sample size ranged from 53 to 56 individual shells over 11 years. ** p<0.001, *p<0.05.