Robert, M. R.; Pessacg, N.; Livore, J. P.; Mendez, M. M.

Climate change and particularly the frequency and intensity of extreme events is affecting the distribution and abundance of species, with drastic consequences on ecological processes and community structure. Long-term records of environmental parameters are indispensable in climatological studies in order to better understand the processes involved. However, such data is usually unavailable for many geographic areas and certain environments, like Patagonian intertidal shores in the Southwestern Atlantic. The use of reanalysis products can help elucidate the climate of the past when in situ information is missing. In this work, we test the performance of reanalysis datasets in reproducing air temperature patterns and extreme hot events (heatwaves) on rocky intertidal environments of Atlantic Patagonia. Thus, we evaluate the degree of correlation between different reanalysis products and air temperature data from loggers placed on rocky shores. We also test whether those products accurately detect the duration, frequency and number of heatwaves and look for historical trends in their features. Our results showed that reanalysis products perform well for assessing broad-scale changes in air temperature patterns. Products were also capable of detecting heatwaves, with little variation in their features for the period 1960-2024. Additionally, real-time field temperatures to which intertidal organisms are exposed were obtained for the first time in the area; reporting heatwaves events. Thereby, reanalysis products complement local data, providing key information to understand the role that temperature increases and extreme heat can have in events like mussels mass mortalities reported locally. In this sense, our results suggest that heatwaves alone wouldn't be explaining the observed mussel losses. This work provides empiric evidence on the usefulness of reanalysis products of intertidal habitats and encourages similar approaches in order to properly understand climatological patterns that can drive ecological processes on coastal habitats.