Shell thickness of Nucella lapillus in the North Sea increased over the last 130 years despite ocean acidification

Ocean acidification and global climate change are predicted to negatively impact marine calcifiers, with species inhabiting the intertidal zone being especially vulnerable. Current predictions of organism responses to projected changes are largely based on relatively short to medium term experiments over periods of a few days to a few years. Here we look at responses over a longer time span and present a 130-year shell shape and shell thickness record from archival museum collections of the marine intertidal predatory gastropod Nucella lapillus. We used multivariate ecological models to identify significant morphological trends through time and along environmental gradients and show that, contrary to global predictions, local N. lapillus populations built continuously thicker shells while maintaining a consistent shell shape throughout the last century.