Environmental change in SW Portugal during the last 3900 years BP: an Ostracoda assessment

Ostracod, geochemical, mineralogical, and sedimentological proxies from a sediment core collected off Sagres (southwestern Portugal) were used to reconstruct Holocene environmental and hydrodynamic changes. Reduced variability of geochemical elements between ∼4000 and ∼1290 calibrated years before present suggests relatively stable conditions, regularly disturbed by higher-energy events. At ∼1290 cal yrs BP, a transition from arid to wetter conditions is suggested based on enhanced terrestrial/detrital input after this time. Ostracod assemblages further captured fine-scale hydrodynamic variability, offering greater sensitivity to oceanographic changes. Our results support a broader pattern of middle-to-late Holocene drying conditions in southern Iberia, followed by a shift to wetter conditions during periods of negative North Atlantic Oscillation (NAO) index. Our study provides new data on offshore ostracods from the western Algarve, underscoring their value for high-resolution paleoenvironmental reconstructions.