Black Sea Zooplankton data from the 'BRIDGE-BS-DEKOSIM Jun 2023' cruise identified with Zooscan

The dataset contains data from samples collected in June 2023 onboard of R/V Bilim-2, at different stations located in Turkish EEZ of Black Sea. The sampling was performed within the BRIDGE-BS project (EU H2020, grant agreement No 101000240). Zooplankton samples were collected by towing a WP-2 net with a 200 µm mesh size and a 57 cm mouth diameter. Lead pieces were attached to the collector to minimize the displacement of the net with the currents. On windy days, the vessel drifted from the point where the net was lowered down. In both cases, the wire angle was calculated and the length of the wire was corrected to collect the whole water column. Hauls were made with a speed of 1 m/s to minimize the spilling out of the water. For the nearshore stations, the net was towed vertically from 4-5 m above the bottom to the surface. For the offshore stations, the net was towed from the start of an anoxic layer (sigma-t, 16.2 kg/m3). The gelatinous organisms were sorted from the sample in the plankton net and analyzed on the board. The rest of the sample were fixed with 5% borax-buffered formaldehyde in 250 ml bottles for the zooplankton analysis. Each sample was filtered with 200 μm and 500 μm mesh to have 2 size fractions. This is because of not missing any rare large organisms while splitting the sample into subsamples. Motoda was used to divide samples into subsamples and at least 1000 organisms were analyzed for each sample. Detritus materials other than zooplankton species were removed from the sample under the stereo microscope. Hydroptic-Zooscan was used to scan the samples. Scanned images were processed with Zooprocess. For each organism, separate images/vignettes were generated from the raw image. These files were then automatically sorted with the Learning Set (Plankton Identifier). Then, the sorting was visually validated using the program XnView. Abundance and biovolume values were expressed in unit volume (m3). The filtration volume was estimated by multiplying the mouth area (πr2) by the wire length. For the biovolume calculation the formula; EBV=4/3π(Major/2) (Minor/2)2 was used (Vandromme et al., 2012). The data file is in OBIS format.