LifeWatch Belgium: FlowCam sampling and lab protocol for imaging microphytoplankton in the Belgian part of the North Sea. v1

In the framework of the Belgian Lifewatch RI, a number of fixed stations in the Belgian Part of the North Sea (BPNS) are visited during mulitdisciplinary campaigns. A grid of nine stations covers the coastal zone and are sampled monthly. Eight additional stations, located more offshore, are sampled on a seasonal basis. For the phytoplankton monitoring, samples are taken using a 55µm mesh size Apstein net, fixed in Lugol's iodine solution and preserved in dark and refrigerated conditions. In the lab, the samples are processed using a FlowCAM VS-4 benchtop model, equipped with a Sony XCD SC90 digital gray-scale camera and VisualSpreadsheet software version 4.2.52. For the monitoring, the FlowCam device is mounted with the 4X magnification and associated hardware to image a particles size range of 55-300µm. The identification of the images data is done with a CNN and followed by a manual validation step to check each predicated image. Since May 2017, this dataset provides micro- and phytoplankton observations, mainly covering diatoms, dinoflagellates and cilliates, for the Belgian Part of the North Sea (BPNS). This published protocol descibes sampling and lab SOPs in detail.