To answer this question, one needs to realize that as one moves upstream in the estuary, the water gets fresher. Whereas the salinity below 2 m is quite similar at the two stations, the salinity in the uppermost 2 m is about a factor of 2 lower in one of the stations. Hence, this must be the station upstream. The density of water increases with decreasing temperature and increasing salinity. At all stations, salinity increased with depth.
Temperature displays a slight decrease in temperature with depth.
Therefore, the density must increase with depth. However, it does not appear that density increases with depth. To solve this paradox, one must realize how much density changes with depth. 6.8, 6.9 and 6.10 show ranges of density in the world-ocean. It is possible that the equipment used on the field trip was not sensitive enough for this purpose.