Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL437	12.05.2014 - 26.05.2014	BIOACID VECTORS BONUS BIO-C3	Arkona Basin Gdansk Bight Baltic Sea Gotland Basin Kiel Bight Bornholm Basin

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
von Dewitz Burkhard	Helmholtz Centre for Ocean Research Kiel (GEOMAR)	Kiel	Kiel	Karte Map

Ziel der Reise / Objectives of Cruise:

This multidisciplinary cruise extended a long-term data series on (eco-)system composition and functioning of the Baltic Sea, with a focus on the deeper basins, collected since 1986 by the GEOMAR Helmholtz Centre for Ocean Research and its predecessors IFM-GEOMAR Kiel and IFM Kiel. The key characteristic of this series is the integration of oceanographic and biological information to enhance understanding of environmental and (fish) population fluctuations, and evolutionary processes in this system, in the context of climate change and anthropogenic stressors. The resulting datasets and samples are essential for a number of ongoing projects, including the large-scale international project BONUS BIO-C3 coordinated by GEOMAR. The spatial focus lies on the Bornholm Basin (the most important spawning area of Baltic cod), but also includes the Western Baltic Sea, Arkona and Gotland Basin and Gdansk Deep, thus covering ICES subdivisions 22, 24, 25, 26 and 28. Specific investigations included a detailed hydrographic survey (oxygen, salinity, temperature, light intensity), plankton surveys (zoo- and ichthyplankton, with the goal to determine the composition, abundance, vertical and horizontal distribution, and nutritional status of species, and to address questions regarding plankton phenology), and pelagic fishery hauls. The latter served to determine size distributions, maturity status, and length – weight relationships of the three dominant fish species in the pelagic system of the Baltic, cod (Gadus morhua), herring (Clupea harengus) and sprat (Sprattus sprattus), as well as the benthic flatfish flounder (Plathichthys flesus). Secondly, various different samples were obtained for more detailed analyses, including gonad samples of cod, stomachs of cod, herring and sprat for dietary analyses, otoliths of cod for aging, and tissue samples of cod, flounder, whiting, plaice and others for genetic analyses. In addition, along the cruise track, hydroacoustic (echosounder) data were collected continuously for later analysis of fish abundance and distribution. While these analyses and samples mainly stood in the context of the continuation of the long-term data series, cod and plankton samples were also taken for new research lines, e.g., by DTU Aqua in Silkeborg, Denmark, and the IOW in Warnemunde, Germany, in the context of the project BIO-C3. In addition, cruise AL 437 included a new work line on board. As started in April on AL 435 measurements of sexual immune dimorphisms in cod and herring were performed. These used Fluorescence Activated Cell Sorting (FACS) to determine the immunocompetence of the individuals. Additionally the cruise was utilized to perform test deployments of a new illuminated high resolution towed camera system. At the moment under development by Henk-Jan Hoving (GEOMAR) it will be utilized for the Future Ocean research project ?In situ observations of Cape Verdean pelagic fauna in a changing ocean'. For summary and narrative of the cruise see attached cruise report AL 437.

Messungen / Measurements