Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Meteor	M87-4	27.06.2012 - 22.07.2012	SOPRAN BIOACID	Baltic Sea

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

Ziel der Reise / Objectives of Cruise:

M87/4 The overarching goal of RV METEOR Cruise 87 Leg 4 was the synoptic acquisition of all relevant processes and variables in connection to formation and consequences of the summer cyanobacterial bloom in the Central Baltic Sea with high temporal and spatial resolution. Optical measurements were performed to allow a better parameterization of remote sensing techniques used to follow the summer bloom. The impact of potentially limiting factors such as the partial pressure of CO2 (pCO2) in combination with other key parameters, or the effect of upper water column turbulence on cyanobacterial development, were investigated using new methodological approaches. Potential mechanisms to understand the so far enigmatic availability of phosphate for the summer bloom were addressed. This includes spatially and temporally highly resolved investigation of turbulent mixing in the upper layer, the acquisition of data of all potentially relevant phosphate reservoirs (organic, inorganic, and cellular), fractionation of phosphate-containing compounds during remineralization, as well as changing P/N/C ratios of particulate material. To assess the influence of mesoscale hydrographic processes on nutrient availability, FS METEOR worked in a stationary mode for several days, while the hydrographical near-field was recorded by a coordinated expedition of IOWs research vessel ELISABETH MANN BORGESE. Incubation as well as open field experiments were designed to address specific questions with respect to function and controlling mechanisms during the cyanobacterial bloom. Additionally the effect of cyanobacterial abundance and light conditions on the production and consumption of environmentally relevant volatiles such as methane, halogenated hydrocarbons or mercury was scrutinized. Though a large number of stations have been sampled, two main stations were investigated several times and for several days in detail: Station TF 271 (57?19,2N; 20?03,0E) in Latvian waters and TF 284 (58?35,0N; 18?14,0E) in Swedish waters. During our mission, TF 271 was characterized by a low initial abundance of cyanobacteria, obviously decaying in the consequence of several storm events untypical for the season, while TF 284 showed are more mature community of cyanobacteria, which also sustained during the mentioned episodes of strong winds. Except for the very last day, no surface accumulations of cyanobacterial were encountered. In the aftermath of the expedition, the results are expected to push forward our understanding of the interplay between cyanobacterial development and production, and the physical (meteorological and hydrographical framework).

Messungen / Measurements

Verankerungen / Moorings