Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL439	04.06.2014 - 19.06.2014		Baltic Sea

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

Ziel der Reise / Objectives of Cruise:

The Baltic Sea is characterized by its distinct horizontal and vertical salinity gradients, with the unique feature that 62% of its surface zone is represented by brackish conditions. Salinity-related distribution patterns and a diversity minimum at brackish conditions are known for higher benthic and pelagic organisms. In a first analysis for microorganisms, based on pyrosequencing of bacterial 16S rRNA genes, we were able to show that also bacterial communities experience distinct shifts at different phylogenetic levels along the salinity gradient. Moreover, there is evidence for an adapted brackish water bacterial community, represented by a phylogenetic member of the Verrucomicrobia. However, knowledge on accordant functional features and potential successions is rare. Thus, based on samples taken and experiments performed on this cruise we will investigate how the shift in bacterioplankton community composition from marine to brackish and limnic conditions affects bacterially mediated functions. This was done by two different approaches: (1) Functional microbial fingerprints will be generated based on the in situ fixed water samples taken by the Automatic Fixation – Injection Sampler (AFIS), resulting in a functionally based biogeographic microbial mapping of the Baltic Sea along its horizontal and vertical salinity gradients. (2) More specifically, microbial activities related to the pelagic carbon cycle will be studied. Manipulative ship-board experimental investigations at five stations of different salinity were done and will assess, besides prokaryotic diversity, microbial functionality covering broad to highly specific bacterial activities related to organic carbon processing. The direct impact of salinity on the composition and function of surface bacterioplankton in the central, brackish Baltic Sea will be examined by experimentally manipulating salinity levels in the laboratory.

Messungen / Measurements