Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Elisabeth Mann Borgese	EMB323	04.08.2023 - 16.08.2023	BLMP+	Baltic Proper Baltic Sea Western Baltic Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Kuss Joachim	Leibniz-Institut fur Ostseeforschung, Warnemunde	Rostock	Rostock

Ziel der Reise / Objectives of Cruise:

The cruise of r/v Elisabeth Mann Borgese No. 323 was done in the frame of the HELCOM monitoring and the IOW long-term observation of the Baltic Sea from August 4th to 16th 2023. During the first two days, a moderate to fresh breeze well allowed to fulfil the station work in the western Baltic Sea. On 6th August a storm low over the southern Baltic Sea deepened that led to wind of about 7 bft that subsequently increased with locally near hurricane force gusts. We entered the port of Sassnitz on 6th August for a scientific crew exchange, but stayed there until the storm calmed on 9th August. We continued the station work at Oder buoy site, and subsequently in the Arkona Sea and along the Thalweg via the Bornholm Basin, the eastern and western Gotland Sea at fair weather conditions. We investigated the hydrographic, hydrochemical and biological state of the Baltic Sea on transect of 2600 km with 87 stations. Thereby, we also took samples for UV Filter and an eDAN sample archive. The water temperature was on average about 19 ?C before and 16 ?C after the storm. Similarly, the air temperature dropped from 17.3 ? 1 ?C in the first 3 days to autumn-like temperatures of 16.3 ? 2 ?C afterwards. In the deep Gotland Sea, the euxinic conditions intensified. In the S?upsk furrow, between the Bornholm Basin and the eastern Gotland Basin, the bottom water oxygen concentrations of about 1.5 mL/L were measured. Moreover, a plume of slightly oxygenated water reached far into the eastern Gotland Basin along the 100 m ? 10 m depth horizon. The weak oxygenated water layer enabled nitrate concentrations of up to 6.6 ?mol/L in an otherwise nitrate depleted environment.

Messungen / Measurements