Description: In a multidisciplinary ex situ experiment, benthic bacterial deep-sea communities from 2,500 m water depth at the Long-Term Ecological Research Observatory HAUSGARTEN (stationPS93/050-5 and 6), were retrieved using a TV-guided multiple corer. Surface sediments (0 - 2 cm) of 16 cores were mixed with sterile filtered deep-sea water to a final sediment dilution of 3.5 fold. The slurries were split and supplemented with five different types of habitat-related detritus: chitin, as the most abundant biopolymer in the oceans, and four different naturally occurring Arctic algae species, i.e. Thalassiosira weissflogii, Emiliania huxleyi, Bacillaria sp. and Melosira arctica. Incubations were performed in five replicates, at in situ temperature and at atmospheric pressure, as well as at in situ pressure of 250 atm. At the start of the incubation and after 23 days, changes in key community functions, i.e. extracellular enzymatic activity, oxygen respiration and secondary production of biomass (bacterial cell numbers and biomass), were assessed along with changes in the bacterial community composition based on 16S rRNA gene and 16S rRNA Illumina sequencing. In summary, differences in community structure and in the uptake and remineralization of carbon in the different treatments suggest an effect of organic matter quality on bacterial diversity as well as on carbon turnover at the seafloor.

Description: Physicochemical parameters and relative abundance of selected nutrient cycling genes were measured in sediment and pore water samples taken from a fish farming area (Site S3 16◦23.097 N, 119◦55.551 E, depth 12.6m) and a control site (Site S1 16◦22.960 N, 119◦54.723 E, depth 15m) not influenced by fish farming. From each site, five pairs of cores representing five biological replicates were collected. One core from each pair was used for physicochemical analysis while the other cores were used for microbial community analysis. Samples from S1 were collected on 2017-06-10 and samples from S3 were collected the following day. Nitrogen (bacterial ammonia monooxygenase/ amoA and nitrite reductase/ nirK) and sulfur (dissimilatory sulfate reductase/ dsrA and sulfur oxidation/ soxB) cycling genes were quantified and normalized against the abundance of the 16S rRNA gene.

Description: Milkfish (Chanos chanos) is one of the most important aquaculture species in Asian countries. These teleost fish are traditionally cultured in outdoor-based systems and therefore have to cope with daily and/or seasonally changing environmental conditions. Temperature changes beyond the optimal range of a fish species are known to induce an endocrine stress response resulting in the release of cortisol via the hypothalamic-pituitary-interrenal axis. Moreover, (thermal) stress induces glucocorticoid-mediated changes in the fish's energy metabolism to cope with the stressor(s) and regain homeostasis. Long-term elevations of cortisol are known to be detrimental for fish performance. In this study, we investigated the stress response of juvenile milkfish, which were exposed to a gradual temperature increase of 1°C per day over 7 days in the range from 26°C to 33°C, followed by an exposure to constant 33°C for 21 days. We quantified ontogenetic (OG) and regenerated (RG) scale cortisol to evaluate chronic stress. To investigate metabolic implications and oxidative stress response, activity levels of key enzymes involved in metabolic (isocitrate dehydrogenase - IDH, lactate dehydrogenase - LDH, electron transfer system - ETS) and antioxidant (superoxide dismutase - SOD, catalase - CAT) related pathways were quantified. Furthermore, we measured available energy resources (protein, carbohydrates, lipids) and potential cellular damage due to oxidative stress (lipid peroxidation - LPO). Finally, changes in the gut microbiome of the milkfish related to the temperature stress were analyzed to elucidate their role in the stress response and interactions with physiological parameters. This study is part of the ACUTE project (AquaCUlture practice in Tropical coastal Ecosystems - Understanding ecological and socio-economic consequences) funded by the Leibniz Association grant SAW-2015-ZMT-4. It is associated with the following publications: Hanke et al., 2019 (doi:10.1016/j.aquaculture.2018.09.016) and Hassenrück et al., 2020 (doi:10.3390/microorganisms9010005). The final OTU table and statistical analysis scripts for Hassenrück et al., 2020 are supplied as further details to this data set.