Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL478	13.05.2016 - 29.05.2016	BONUS BIO-C3	Arkona Basin Baltic Sea Gotland Basin Kiel Bight Bornholm Basin Gdansk Bight

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

Ziel der Reise / Objectives of Cruise:

Physical, chemical, biological research and fishery oceanography 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. The series has been collected in similar form since 1986. A key characteristic of the cruise is the integration of oceanographic and biological information to enhance understanding of environmental and (fish) population fluctuations, and evolutionary processes in this system. The resulting datasets and samples are an essential component of the international EU project BONUS BIO-C3 coordinated by GEOMAR. The spatial focus lay on the Bornholm Basin (the most important spawning area of Baltic cod), but also included the Western Baltic Sea, Arkona and Gotland Basin, Gdansk Deep, and Stolpe Trench. Specific investigations included a detailed hydrographic survey (oxygen, salinity, temperature) of the Bornholm Basin, plankton surveys (zoo- and ichthyplankton, with the goal to determine the composition and the abundance and vertical and horizontal distribution of species, and to take samples for later measurements of nutritional condition), and pelagic fishery hauls for clupeid and gadoid fish. The latter served to determine stock structure, gonadal maturation, stomach contents, and egg production of sprat and cod, and to sample tissue for later genetic analyses and otoliths for age estimatation of individual cod. The abundance and distribution of fish species in the investigated area was also assessed with hydroacoustic methods. Additional cruise components were: (i) cod gonad sampling for histological and fecundity studies; (ii) vertically resolved phytoplankton and zooplankton sampling for studies of plankton phenology.

Messungen / Measurements