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1. Wochenbericht FS Alkor Reise 571, Fahrtabschnitt 21.- 25.04.2022

April 15th – April 24th 2021 Kiel (Germany) – Kiel (Germany) BALTIC APRIL 2021

Modern digital scientific workflows - often implying Big Data challenges - require data infrastructures and innovative data science methods across disciplines and technologies. Diverse activities within and outside HGF deal with these challenges, on all levels. The series of Data Science Symposia fosters knowledge exchange and collaboration in the Earth and Environment research community. We invited contributions to the overarching topics of data management, data science and data infrastructures. The series of Data Science Symposia is a joint initiative by the three Helmholtz Centers HZG, AWI and GEOMAR Organization: Hela Mehrtens and Daniela Henkel (GEOMAR)

Protecting the ocean has become a major goal of international policy as human activities increasingly endanger the integrity of the ocean ecosystem, often summarized as ‘‘ocean health.’’ By and large, efforts to protect the ocean have failed because, among other things, (1) the underlying socio-ecological pathways have not been properly considered, and (2) the concept of ocean health has been ill defined. Collectively, this prevents an adequate societal response as to how ocean ecosystems and their vital functions for human societies can be protected and restored. We review the confusion surrounding the term ‘‘ocean health’’ and suggest an operational ocean-health framework in line with the concept of strong sustainability. Given the accelerating degeneration of marine ecosystems, the restoration of regional ocean health will be ofincreasing importance. Our advocated transdisciplinary and multi-actor framework can help to advance the implementation of more active measures to restore ocean health and safeguard human health and well-being.

Protecting the ocean has become a major goal of international policy as human activities increasingly endanger the integrity of the ocean ecosystem, often summarized as "ocean health". By and large, efforts to protect the ocean have failed because, among other things, (1) the underlying socio-ecological pathways have not been properly considered, and (2) the concept of ocean health has been ill defined. Collectively, this prevents an adequate societal response as to how ocean ecosystems and their vital functions for human societies can be protected and restored. We review the confusion surrounding the term "ocean health" and suggest an operational ocean-health framework in line with the concept of strong sustainability. Given the accelerating degeneration of marine ecosystems, the restoration of regional ocean health will be of increasing importance. Our advocated transdisciplinary and multi-actor framework can help to advance the implementation of more active measures to restore ocean health and safeguard human health and well-being.

This multidisciplinary cruise extended a long-term data series on ecosystem composition and functioning of the deeper basins of the Baltic Sea that has been collected in similar form since 1987. The key characteristic of the cruise was the integration of oceanographic and biological information to enhance understanding of environmental, plankton dynamics and fish population fluctuations, and ultimately, evolutionary processes in this system. The spatial focus lay on the Bornholm Basin as most important spawning area of Baltic cod, but also included the Western Baltic Sea, Arkona and Gotland Basin, Gdansk Deep, and Stolpe Trench. All objectives of the cruise were achieved, benefiting from perfect weather conditions and flawless performance of all instruments and gear. The detailed hydrological survey (oxygen, salinity, temperature) of the entire cruise area showed higher water temperatures and an improvement of the oxygen situation in deep water layers compared to the same time period in 2018. Plankton surveys (zoo- and ichthyplankton including gelatinous plankton, 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) showed a much higher abundance of jellyfish larvae (“ephyrae”) and small adults than in 2018. Regarding fish larvae, sprat and flounder larvae were abundant but very few cod larvae were present throughout the cruise area, both of which was consistent with the situation in previous years. Pelagic fishery hauls were carried out as planned to determine stock structure and to obtain a range of different samples (gonads, livers, stomachs, tissue samples, otoliths) for cod, whiting, sprat and herring as well as different flatfish species, and are the foundation for a range of different individual-level genetic and ecological analyses to be carried out in the laboratory on land. The abundance and distribution of fishes in the cruise area was also assessed continuously over the duration of the cruise with hydroacoustic methods. As in previous years, cod, herring, sprat and flounder dominated catches. Catches of cod increased compared to 2018, but the absence of large cod individuals in particular in Bornholm Basin was consistent with observations in previous years. Finally, the work for all additional collaborative projects, including in-depth sampling of planktonic food webs for dietary tracer work, sampling and experimental work of photosynthesis and respiration rates of different phytoplankton fractions and finally, pelagic fish stomach and plankton sampling for eDNA assessments was carried out successfully. The resulting data- and sample sets support ongoing projects in the Research Unit Marine Evolutionary Ecology at GEOMAR, as well as the EU Horizon 2020 project GoJelly and several international collaborations.