Shell properties of the limpet Patella vulgata along a wide latitudinal gradient in Norway: responses to environmental conditions in arctic and sub-arctic water

Ocean acidification and warming driven by climate change pose a significant threat to marine calcifiers, as declining pH and calcium carbonate saturation can impair shell formation. Polar regions are especially vulnerable due to the higher solubility of CO2 in cold waters and the low buffering capacity. This study investigates how environmental variability along a wide latitudinal gradient in Norway affects the shell properties of the common European limpet Patella vulgata. Samples were collected across five coastal sites spanning from temperate to Arctic conditions (from 63 to 70°N). Shell parameters, including shell thickness, bulk density, and porosity, and the physiological index (Condition Index), were analyzed in relation to temperature, pH, and carbonate saturation state. Despite significant spatial differences in skeletal properties, the most porous and least dense shells were not found at the site with the lowest saturation, and the Condition Index remained stable across sites. These findings suggest that P. vulgata may maintain shell growth and physiological condition even under Arctic-like conditions and low calcium carbonate saturation. This resilience contrasts with the narrower tolerance of Antarctic limpets like Nacella concinna, suggesting P. vulgata as a useful model for studying adaptation to climate-driven stressors. Indeed, the next step of this study is to investigate the expression of stress-related genes.