They also reported that the salinity decreases to 16–17 PSU when the Danubian influence is felt in the area from March to August each year. We made similar observations in the same area. Less

saline waters (< 17 PSU) are recorded in February 1999 and during the period from April to August 1999. Our observations also show that the salinity of the upper layer is less than 15 PSU (14.3 PSU at station K2 and 14.5 PSU at PD0332991 mouse station K0) in July 1999. The thickness of this water layer is ∼ 40 m at station K0 and ∼ 30 m at station K2. This rather thick and much diluted water mass clearly shows the strong influence of Danube water in the area (Sur et al., 1994 and Sur and Ilyin, 1997). Temperature profiles indicate a two-layered stratification in the winter months but three layers in the summer months. The upper layer temperature range is ∼ 6–26 °C at both stations K2 and K0. The coldest surface water is observed in February (6 °C).

Its thickness is ∼ 15 m at K0 and several metres at K2. Below this cold surface layer, the temperature increases slowly to ∼ 8 °C, then rises rapidly to 11 °C in the interface depth. From March onwards, surface waters warm up as a result of atmospheric Selleck BGB324 heating. The surface water temperature reaches a maximum in August at stations K0 and K2. When the surface temperature is > 8 °C, the cold layer appears between the warm surface layer and the lower layer. The surface water thickness increases while almost the CIW thickness decreases at both stations from March to October. However, this is not a regular feature. For example, in July when Danubian waters are observed in the area, the surface layer is rather thick and the amount of cold water is small compared to June and August. This can be explained by the 40 m thick layer of Danubian waters influencing the area. The mean discharge of the River Danube is 6550 m3 s− 1, the highest

discharges are observed between March and July, and the lowest ones in August-November (Lampert et al. 2004). Sur et al. (1994) reported that Danube-influenced water can arrive in the vicinity of the Bosphorus within the space of 1–2 months, assuming a mean current speed of 10–20 cm s− 1. One other exception was observed in September 1999, when the surface layer was rather thick, and cold water (the minimum temperature was nearly 12 °C) was observed only at station K2. The reason for the absence of cold water at station K0 could be explained by the strong Rim Current, flowing eastwards at station K2. One month later, in October 1999, the base of the surface layer was at a shallower depth, and CIW was thicker than in September. In November 1999, the water column had almost the same temperature (∼ 15 °C) and CIW disappeared. In December 1999, the surface layer temperature was about 11 °C at both stations, but there was a cold layer with a minimum temperature of 9 °C below 40 m depth at station K2.