ALBERT

Description: The data set was acquired during the PHYCOB cruise in the frame of the Eurofleets+ programme (https://www.eurofleets.eu/2021/10/22/phycob-an-international-oceanographic-expedition-into-the-western-black-sea-coordinated-by-the-alfred-wegner-institut-helmholtz-zentrum-fur-polar-und-meeresforschung-awi/) within the Regional call in the territorrial waters of Romania and Bulgaria in the Western Baltic Sea from 11th to 17th September 2021. The aim of the cruise was to assess the occurrence of potentially harmfal algae and their associated phycotoxins in the Black Sea and the accompanying environmental parameters. Sampling was performed by CTD casts and Rosette water sampling in addition to vertical phytoplankton net hauls from 30 m depth to surface. The determined parameters include the following: Quantitative phytoplankton cell counts in water samples, qulitative determination of toxigenic species next generation sequencing data in plankton net concentrates, monoclonanal cultures established from water sample isolates, phycotoxins in plankton net concentrates, inorganic nitruinets (nitrate/nitrite, phosphate, silicate) , vitamin B12, particulate organic carbon, particulate organic nitrogen, flowcytometry data, and CTD data (temperature, salinity, chlorophyll-a, oxygen, turbidity, radiance).

Description: Nitrite and nitrate as nitrogen (NO3+NO2), ammonium as nitrogen (NH4+), ortho-phosphate as phosphorus (o-PO4) and silica (SiO2) analyzes were measured by a QuAAtro39 Continuous Segmented Flow Analyzer consisting of an autosampler, a peristaltic pump, a chemistry manifold, a detector and data acquisition software. This protocol is in accordance with standard methods for the examination of water and wastewater. Dissolved oxygen (DO) was measured by using the Winkler method, in which a divalent manganese solution and strong alkali are added sequentially to the samples. Thus, dissolved oxygen rapidly oxidizes an equivalent amount of divalent manganese to basic hydroxides of higher valency states. With the presence of iodide ions in acidic conditions, the oxidized manganese reverts to its divalent state, and meanwhile, the iodine equivalent to the dissolved oxygen in the sample is released. This released iodine is titrated with a standardized thiosulfate solution and the dissolved oxygen value in the sample is calculated by potentiometric measurement using Metrohm 905 Titrando automatic titrator system. Dissolved oxygen samples are taken and analyzed in duplicate. The relative percent difference (RPD) of duplicates did not exceed 4.3% (Average is 0.62%). All results were also compared with the CTD dissolved oxygen data. pH measurements of sea waters were measured in lab by Mettler Toledo SevenMulti pH meter. The pH meter was calibrated every two days with the calibration standards at the values of 7.00 and 9.21. During the measurements, the pH values were recorded together with the current sample temperature values.