Observing abilities of satellite-tagged sea turtles: comparison of reconstructed temperature profiles with ocean model data in the Adriatic and Ionian Seas.

In situ and satellite-based oceanographic data are essential to understanding marine dynamics. In this study, we explore the ability of seawater temperature profiles along the water column, reconstructed from data collected by satellite-tagged loggerhead sea turtles, to capture ocean thermal structures. Temperature and depth data collected by seven loggerhead turtles (Caretta caretta) equipped with satellite tags in the Adriatic and northern Ionian Seas were compared with Copernicus Marine model products. Discrepancies between observed and CMEMS MedFS data primarily occur at intermediate (15 to 50 m) and greater depths (50 to 100 m), especially during summer and winter seasons, when stratification and limited deep-water observations reduce accuracy. These differences were most pronounced in dynamically complex areas such as the Western Adriatic Coastal Current (WACC) region and in the northern and middle Adriatic Seas, where fine-scale coastal processes and intense winter cooling challenge the resolution of both the CMEMS MedFS data and the animal-borne sensors. Although limited in sample size, the dataset offers a valuable opportunity to evaluate the additional observational insights provided by animal-borne sensors in challenging oceanographic environments, emphasizing the complementary role of turtle-borne observations within existing monitoring networks.