Seasonal exposure alters climate change vulnerability estimates of marine species

Climate vulnerability assessments are valuable tools for understanding and evaluating the potential impacts of climate change on marine species. Typically, these approaches combine different data sources to estimate indicators across the main dimensions of vulnerability. Life-history traits are widely used to assess species sensitivity, whereas environmental drivers and management/governance characteristics are commonly used to estimate exposure and adaptive capacity, respectively. Here, we estimated the vulnerability of the 74 most important commercial marine species in Portugal using seasonally resolved exposure estimates and compared the resulting classifications with a previous assessment based on annual data. The assessment was conducted for two climate projections across three areas of the Portuguese coast to explore potential regional and future differences in climate vulnerability classifications. Our results showed significant differences between annual and seasonal vulnerability assessments. Overall, assessments using seasonal exposure yielded lower vulnerability categories than the annual assessment, for species in the moderate and low ranges due to lower exposure scores. In contrast, species classified in the high and very high vulnerability ranges remained mostly consistent between annual and seasonal assessments. Regional and scenario contrasts were less evident than the differences observed between annual and seasonal classifications. These findings indicate that incorporating seasonally resolved exposure information can influence expert-based vulnerability classifications and provide a more temporally explicit basis for climate vulnerability assessment.