ALBERT

Description: In the paper "Salinity as a tool for strain selection in recirculating land-based production of Ulva spp. from germlings to adults" (Cardoso et al. 2023) the relative growth rates of germlings of different Ulva species and strains were measured to evaluate the impact of different salinity treatments. We hypothesised that, since their early stages, salinity impacts the relative growth rate of the seaweeds and that different strains are adapted to different salinities. With this data it was possible to use salinity as a tool for selecting the strain with the highest and determine the optimal salinity to grow its germlings under a nursery setting to supplement a large-scale production. Four strains were tested (U. lacinulata and U. linza from the NE-Atlantic and U. lacinulata and U. flexuosa from the Mediterranean). The NE- Atlantic strains were collected in the Óbidos Lagoon, Portugal in January 2021 and were cultivated in laboratory conditions in the Alfred Wegener Institute (AWI), Bremerhaven, Germany. The Mediterranean strains belong to an AWI collection and were isolated in 1986 and 1987 (U. flexuosa and U. lacinulata, respectively). The cultivation of the Mediterranean species with the purpose of using them for experiments started in June 2021. To recreate the conditions of a nursery system, the strains were grown previously and during the experiment in a medium of artificial seawater (Seequasal-Salz, Seequasal Salz Production and Trade GmbH, Münster, Germany) enriched with half-stregth Provasoli (PES; Provasoli 1968; modifications: HEPES-buffer instead of TRIS, double concentration of Na₂glycerophosphate; iodine enrichment following Tatewaki, 1966). Three germlings with similar size from each species and population were placed into multi-well plates and subjected to different salinity treatments (10, 15, 20 and 30 PSU) (n = 3). The germlings were cultivated for 3 weeks. Because of the small size of the germlings, measuring the fresh weight was not possible and, in this experiment, pictures of the germling development were taken every week and the area of the germlings was measured with the software Image J (Rasband 2012). The difference in size was later used to determine their relative growth rate.

Description: This study examined the metabolic response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal (FM) replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). The feeding experiment was carried out from April to July 2019 in the Centre for Aquaculture Research (ZAF) at the Alfred Wegener Institute for Polar and Marine research in Bremerhaven, Germany. The juvenile turbot (Scophthalmus maximus) were purchased from France Turbot (L'Épine, France) and acclimated to the recirculating aquaculture system (RAS) for 2 weeks prior to starting the 16 weeks experimental trial. To elucidate the effects of the protein sources and the level of FM replacement on the metabolic response of the fish, a 1H‐nuclear magnetic resonance (NMR) spectroscopy was used to assess the metabolic profiles of muscle and liver tissue after feeding the fish the experimental diets for 16 weeks. Feed, muscle, and liver samples were ground under liquid nitrogen and approx. 200–250 mg tissue was homogenized in 5x volume of ice‐cold 0.6 M perchloric acid (PCA) (w:v). After one cycle of 20 s at 6000 rpm and 3 °C, using Precellys 24 (Bertin Technologies, Montigny‐le‐Bretonneux, France), samples were sonicated for 2 min at 0 °C and 360 W (Branson Sonifier 450, FisherScientific, Schwerte, Germany). Homogenates of the experimental diets, muscle and liver tissues were centrifuged for 2 min at 0 °C and 16,000 g, and supernatants were neutralized with ice cold potassium hydroxide (KOH) and PCA to pH 7.0–7.5. To remove precipitated potassium, perchlorate samples were centrifuged again for 2 min at 0 °C and 16,000 g. The entire supernatant was transferred, shock‐ frozen in liquid nitrogen, and stored an −80 °C for later analysis. One‐dimensional 1H‐NMR spectra for feed and tissues extracts were acquired using a vertical 9.4 T wide bore magnet with Avance III HD (Bruker‐GmbH, Ettlingen, Germany) at 400.13 MHz with a 1.7 mm diameter triple tuned (1H‐13C‐15N) probe. Each spectrum was processed and analyzed with Chenomx NMR Suite 8.4 software (Chenomx Inc., Edmonton, Canada). Before analyzing, the spectra were corrected for phase, shim and baseline and calibrated to trymethylsilyl proprionate (TSP) signal (at 0.0 ppm).