Description: Fahrtabschnitt 14.05. - 22.05.2022

Description: Physical, chemical, biological oceanography and fisheries research 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 feed into the EU projects BONUS BLUEWEBS and Horizon 2020 GoJelly, and the US NSF project "Evolutionary Responses to Global Change in Salinity and Temperature". 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. Specific investigations included a detailed hydrological 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 and otolith samples for individual-level genetic and ecological analyses of cod. The abundance and distribution of fishes in the cruise area was also assessed with hydroacoustic methods. Additional cruise components were: (i) cod gonad sampling for fecundity studies and liver sampling for parasite studies. (ii) vertically resolved phytoplankton and zooplankton sampling for studies of plankton phenology. (iii) in-depth sampling of planktonic food webs for dietary tracer work. (iv) copepode Eurytemora affinis sampling along the salinity gradient of the Baltic Sea for the study of local adapations.

Description: Dates of Cruise: 15.05. – 30.05.2018 Areas of Research: Physical, chemical, biological and fishery oceanography Port Calls: Riga. Latvia, 22.05.2018

Description: Laufzeit des Vorhabens: 01.01.2014-31.12.2017 : Berichtszeitraum: 01.01.2014-31.12.2017

Description: Editorial

Description: 15.05 – 30.05.2019 The AL522 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 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. 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. Specific investigations included a detailed hydrological survey (oxygen, salinity, temperature) of the cruise area, 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), and pelagic fishery hauls. The latter served to determine stock structure, gonadal maturation, stomach contents, and egg production of sprat and cod, and to sample tissue and otolith samples for individual-level genetic and ecological analyses of cod. The abundance and distribution of fishes in the cruise area was also assessed with hydroacoustic methods. Additional cruise components were: (i) cod gonad and liver sampling for fecundity + parasite studies, (ii) vertically resolved plankton sampling for studies of plankton phenology (iii) depth-resolved sampling of microplastic using an neuston sledge (iv) sampling and experimental work of photosynthesis rates of different phytoplankton fractions (v) eDNA filter sampling to compare with traditional net based methods.

Description: Highlights: • Larvae upregulate genes associated with fatty acid and glycogen synthesis under moderate ocean acidification (OA) • Larvae under high levels of OA fail to regulate • Dysfunctional metabolism and stress associated with pathologies in internal organs • Lack of differential gene regulation and stress response in juveniles correspond to a higher resilience to OA stress Elevated environmental carbon dioxide (pCO2) levels have been found to cause organ damage in the early life stages of different commercial fish species, including Atlantic cod (Gadus morhua). To illuminate the underlying mechanisms causing pathologies in the intestines, the kidney, the pancreas and the liver in response to elevated pCO2, we examined related gene expression patterns in Atlantic cod reared for two months under three different pCO2 regimes: 380 μatm (control), 1800 μatm (medium) and 4200 μatm (high). We extracted RNA from whole fish sampled during the larval (32 dph) and early juvenile stage (46 dph) for relative expression analysis of 18 different genes related to essential metabolic pathways. At 32 dph, larvae subjected to the medium treatment displayed an up-regulation of genes mainly associated with fatty acid and glycogen synthesis (GYS2, 6PGL, ACoA, CPTA1, FAS and PPAR1b). Larvae exposed to the high pCO2 treatment upregulated fewer but similar genes (6PGL, ACoA and PPAR1b,). These data suggest stress-induced alterations in the lipid and fatty acid metabolism and a disrupted lipid homeostasis in larvae, providing a mechanistic link to the findings of lipid droplet overload in the liver and organ pathologies. At 46 dph, no significant differences in gene expression were detected, confirming a higher resilience of juveniles in comparison to larvae when exposed to elevated pCO2 up to 4200 μatm.

Description: 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.

Description: Highlights: • Non-indigenous species (NIS) are increasingly recognized as a matter of concern. • The microbiome of native and NIS gelatinous zooplankton organisms are compared. • Next generation sequencing confirms sign. Species specific microbiome differences. • Indicator OTUs include bacteria which contain known pathogenic strains. • Microbiome monitoring of NIS should be considered for aquaculture risk assessments. Abstract: The translocation of non-indigenous species (NIS) around the world, especially in marine systems, is increasingly being recognized as a matter of concern. Species translocations have been shown to lead to wide ranging changes in food web structure and functioning. In addition to the direct effects of NIS, they could facilitate the accumulation or translocation of bacteria as part of their microbiomes. The Baltic Sea harbours many non-indigenous species, with most recent detection of the jellyfish Blackfordia virginica and the comb jelly Mnemiopsis leidyi in the low saline southwestern Baltic Sea. In this study, we used a multidisciplinary approach and investigated three gelatinous zooplankton species that co-occur in the same environment and feed on similar zooplankton food sources but show different histories of origin. The aim was to conduct a comparative microbiome analysis of indigenous and non-indigenous gelatinous zooplankton species in the low-saline southwestern Baltic Sea. Next-generation 16S rRNA marker gene sequencing of the V1/V2 region was employed to study the bacterial microbiome compositions. All tested species showed significant differences in their microbiome compositions (one way ANOSIM, R = 1, P 〈 0.008) with dissimilarities ranging from 85 to 92%. The indigenous jellyfish Aurelia aurita showed the highest bacterial operational taxonomic unit (OTU) richness. The overall differentiation between microbiomes was driven by eight indicator OTUs, which included Mycoplasma and Vibrio species. These bacteria can be problematic, as they include known pathogenic strains that are relevant to human health and aquaculture activities. Our results suggest that the impact assessment of NIS should consider potential pathogenic bacteria, enriched in the environment due to invasion, as potential risks to aquaculture activities.