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: Raw data acquired by an SBE21 thermosalinograph and an auxiliary SBE38 temperature sensor (Sea-Bird Scientific, USA) installed in an underway seawater flow-through system on board RV Heincke were processed to yield a calibrated and validated data set of seawater temperature and salinity along the cruise track. The seawater inlet is located at a depth of 2 m. The raw hexadecimal data were downloaded from the DAVIS SHIP data base (https://dship.awi.de) at a resolution of 1 s, and converted to temperature and conductivity using the pre-deployment factory calibration coefficients. The converted data were averaged to 1 min values, outliers were removed, and sensor drift was corrected using coefficients obtained from a post-season calibration performed at Sea-Bird at the end of the measurement season. Salinity was calculated from internal temperature, conductivity and pressure according to the PSS-78 Practical Salinity Scale. Processed data are provided as 1 min means of seawater temperature, conductivity and salinity, aligned with position data taken from the master track. Quality flags are appended according to the SeaDataNet Data Quality Control Procedures (version from May 2010). More details are described in the attached processing report.