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  • Study of spatial and temporal variations of hydrographic, hydrochemical and biological parameters in the frame of the COMBINE Programme of HELCOM , combined with long term observations of IOW

  • 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).

  • Studies of the spatial and temporal variations of hydrographic, hydrochemical and hydrobiological parameters in the frame of the COMBINE Programme of HELCOM

  • - Surveying activities, Instrument testing, Scientific Diving, Training, Oceanographic and acoustic measurements underway and near German Baltic Station FINO2 - Preparations/Redeployment/Mobilisation of German Baltic MARNET Station ODER BANK Oceanographic measurements at IOW MARNET locations , Scientific Diving, Oceanographic and acoustic measurements near German Baltic Stations ODER BANK, ARKONA SEA

  • The cruise was undertaken for two main goals:\n\nMOCA: Investigation of processes and organisms involved in the N-cycle of oxygen minimum zones of the Baltic Sea. Of special interest was thereby the stratification and adaptation of organisms to the physicochemical gradient of the redoxcline in the central Gotland Basin. \nSOPRAN: Investigation of volatile halogenated organic compounds with special focus on their biogenic production and degradation processes. Therefore, samples from surface water and the chlorophyll-maximum were taken in order to account for different phytoplankton and bacterioplankton communities throughout the southern and central Baltic Sea.\n\nFor both projects, numerous CTD casts were performed to obtain physicochemical data (from CTD sensors), nutrient data (onboard laboratory analyses of water obtained from CTD rosette sampler) and samples for future chemical and biological analyses (from CTD rosette sampler).

  • The analysis of the interplay between the transfers of matter and structure of marine communities downstream an upwelling center in Northern Benguela region was the overall aim of the exercise. The hydrographic investigations carried out along the repeated transects will contribute to answering the following questions: (1) To what fraction do the coastal upwelling and curl driven upwelling contribute to the vertical transports on the shelf and how change this transports temporally and spatially during the evolution of an upwelling event? (2)How do nutrient concentrations, their stoichiometric ratios as well as oxygen conditions change on horizontal and vertical direction down steam the upwelling center? Marine biological objectives are focused on changes with increasing distance to the shore regarding: (1)Communities from microbes to macro-plankton and of benthic organisms, (2) Matter transfer, especially by new and regenerated production,(3)N2 fixation,(4) Autotrophic and heterotrophic processes, (5) Vertical flux of organic carbon, (6) Pelago-benthic coupling,(7) Importance of suboxic conditions, for community structure, and (8) Potential co-limitation of phytoplankton growth by phosphate and iron in the oceanic waters. The working program of Leg MSM 18/5 was situated in the Northern Benguela upwelling region. The ship left Walvis Bay harbor at favorable weather conditions in the afternoon of August, 23rd. The situation in the working area at off Terrace Bay met the climatological characteristics e.g. in respect to coastal (Ekman) upwelling strength. The program started with benthos work at 25m isobath, setting up a mesocosm experiment on deck and deployment of the sediment trap at 20° 16,16' S; 12° 32,83' E (see schedule) close to a current meter mooring which was already deployed at the end of the pervious leg MSM18/4. After taking over a delayed container with important scientific equipment of WHOI in Walvis Bay at 25./26.08.2011, we started with vertical profiles on transects perpendicular to the coast located between 20°1.90'S, 12°57,22'E and 21°4.86'S, 11°9,81'E four times (see ship track and schedule) deploying the CTD probe and multi plankton sampler (MPS midi). Benthologists used van Veen grab, box corer and occasionally a dredge. Station distances ranged from 5.6 n.m. to 11.2 n.m. in near shore areas and to 16.8 km seaward the shelf break (see MSM 18/5 station map). Transect IV was extended up to 22°22.12'S, 8°57,09'E in order to discover the seaward extension of upwelling phenomena. After the first two transects, we went to Walvis Bay harbor for bunkering (c.f. map of ship track). Returned in the working area, we replaced the current meter mooring and the sediment trap from the first position to 20°31,19'S, 12°8,47' E and collected samples for vertical flux measurements and benthos. Transect III started at Sept.,8th considering a 12h time shift in respect to the two first transects in order to diminish effects daily variability like vertical migration of organisms on average vertical (x-z-) patterns. Transect work always started at the innermost position. When returning, a Video-plankton-Recorder/CTD unit was towed undulating in the upper 150m in order to get highly resolved information on plankton and CTD-fluorescence patterns. At Sept., 18th we searched for a specific mussel (genus Nuculana) which is able to live in low oxygen conditions utilizing metabolites provided by symbiontic bacteria. For this purpose we took samples along an oxygen gradient at 22° 30'S (see MSM18/5 track). At Sept.,19th , we performed a final meeting shared first results like a poster imaging zooplankton distribution of transect II jointly compiled by participants of Namibia and Spain. We arrived Walvis Bay in the evening of Sept.,19th.

  • The cruise took place in the framework of the BIOACID project where the potential effects of ocean acidification on the plankton community in the Baltic Sea are studied. The response of bacteria and phytoplankton community towards changing pCO2 concentrations was investigated by means of a routine sampling scheme at all stations. At two stations also N-cycling processes at depth were studied (see below). Altogether the data set will help to constrain the potential role of the cyanobacteria bloom in summer under rising inorganic carbon concentrations.

  • The EMB cruise 06EZ1118 was carried out in frame of the Baltic Sea monitoring activities of the IOW. The main goal of the cruise is to contribute to the knowledge about the mesoscale dynamics in the western and central Baltic. Along a transect from the Darss Sill to the northern Gotland basin towed CTD and current measurements supply hydrographic measurements with a high spatial resolution. This synoptic data set will provide information about the spatial variability of key hydrographic parameters at the time of thermocline erosion in late autumn. Additionally, the gathered data will be used in frame of the Baltic monitoring program and for validation of the IOW numerical modells.\nThe cruise will also be used for several device tests and mooring maintenance of the GotlandNE long term mooring.\nThe working program of the cruise consisted of the following packages:\n(1) Measuring of mesoscale hydrographic patterns in the upper layer and the halocline of the Baltic at depth between 0 und 150m with a combined ScanFish/TADCP transect from the Darss Sill to the northern Gotland basin. (2) Maintenance of the long term mooring Gotland NE. (3) CTD transect along the ScanFish transect for covering the deep layers that were not measured by the ScanFish. (4) Test of a new ADCP measuring method, that will allow the contemporary measurement of all main turbulence parameters with a single device.

  • The Baltic Sea with its natural gradients and strong reactions to climate change and anthropogenic activity can be used in an ideal way to examine basic ecological processes and their variability in marine ecosystems. The most striking characteristics of the Baltic Sea are the extended gradients in primary (topography, energy, salinity) and secondary (organisms, matter flux, oxygen, nutrients, sediments) environmental properties as a result of different dynamical processes. Leg M87/3a investigates the impact of salinity gradients on degradation of terrestrial dissolved organic matter (tDOC), microbially mediated processes, and on the structure and function of pelagic microbial communities in the Baltic Sea. Following aims were central to this study: (1) Assessment of structure and (selected) functions of pelagic microbial communities (Bacteria, Archaea, Zooplankton) in order to examine whether salinity-related phylogenetic shifts in microbial communities imply relevant functional changes. It provides the general background for the more specific question of decomposition dynamics of imported terrigenous compounds. (2) Quantification, chemical characterization and decomposition of discharged terrestrial DOC from Northern (arctic) soils in relation to microbial diversity. The aim is to assess the decomposition capacity for organic matter, particularly the degradation potential for introduced terrestrial carbon compounds, along the horizontal salinity gradient of the Baltic Sea. The overall aim of these studies is to gain a comprehensive understanding of the effect of imported terrigenous and autigenous organic material on microbial decomposition processes within the salinity and gradients of the Baltic Sea.   To reach this goal, in general water, fixed water, zooplankton, as well as sediment samples were taken throughout a transect of 27 stations, covering the whole Baltic salinity gradient. Isotopes were analyzed continuously. Morever, microbial decomposition experiments were directly done on board.

  • Monitoring Cruise in the frame of the Combine programme of HELCOM