This paper presents two dinoflagellate cyst records from the south-western shelf of the Black Sea. A new site, MAR05-13, from the Sakarya shelf is described and placed into context with site MAR02-45, ∼250 km distant on the Thracian shelf. The records provide a centennial resolution of surface water conditions in the Holocene. Analysis of the data suggests that the surface salinity of the south-western shelf increased in a gradual and progressive manner. In the period ∼11 000–9000 cal a BP the assemblages suggest surface-water salinities between 7–13 psu. The initial arrival of euryhaline species, ∼8100 cal a BP, is linked to the reconnection of the Black Sea and Marmara Sea. The suggested surface water changes related to the reconnection took approximately 1000 years. Following this initial change in assemblages, a further increase in the number of euryhaline species is noted between 5000 and 4000 cal a BP. This is linked to the establishment of more saline surface-water conditions, close to present-day values. The record for MAR05-13 highlights the complexity of the changes in cyst assemblages during the mid-Holocene. Copyright © 2012 John Wiley & Sons, Ltd.