Chlorophyll a concentration is generated from daily Ocean Colour data provided by the SeaWifs (1998-2003), the MERIS (2003 to 2011), the MODIS (2003 to 2017) and Sentinel-3 (2017 to current) satellite sensors. The algorithms used to derive data from the satellite sensors correspond to the best available algorithms given a water type and satellite sensor. Data is supplied at approximately 1 km resolution for the period 1998-2017 and 300m for the period 2017-current on a geographical equidistant grid covering the described region. The quality control and algorithm merging procedure applied was developed during the JMP-EUNOSAT project. The suitability of the satellite-based Chlorophyll a product for eutrophication assessment was evaluated by a comparison analysis with in-situ datasets for all assessment areas in the Greater North Sea. A validation of the yearly mean and P90 chlorophyll a products using the national monitoring chlorophyll a data obtained using different analytical techniques (i.e. HPLC, spectrophotometry, fluorometry) yielded a median error of 35.19% and 39.05% respectively. This shows a good general agreement between in-situ and satellite observations. More details are available in: https://www.informatiehuismarien.nl/publish/pages/162863/2_chlorophyll_satellite_data.pdf Van der Zande, D., Lavigne, H., Blauw, A., Prins, T., Desmit, X., Eleveld, M., Gohin, F., Pardo, S, Tilstone, G., Cardoso Dos Santos, J. (2019). Coherence in assessment framework of chlorophyll a and nutrients as part of the EU project ‘Joint monitoring programme of the eutrophication of the North Sea with satellite data’ (Ref: DG ENV/MSFD Second Cycle/2016). Activity 2 Report. 106 pp.

Phytoplankton for the lifeWatch phytoplankton observation in the Belgian part of the North Sea (https://doi.org/10.14284/330) are sampled by a 55µm mesh size Apstein plankton net deployed at the surface of each station. The 55µm mesh size Apstein net is a commonly net used for phytoplankton sampling. The samples are fixed with lugol and stored in dark conditions at 4°C at the Marine Station in Ostende. The samples are then filtered with a 300 µm mesh size net (to remove large particles and organisms) and processed with a FlowCAM VS-4 at 4X magnification, using a FC300 flow cell, at a flow rate of 1.7mL/min. The analysis combines the technologies of flow cytometry, microscopy and image analysis, and the produced images are processed with the software VisualSpreadsheet (improvements of the software are ongoing at Marine Observation Center in Ostende , and the software will be updated in the coming years) allowing a semi-autonomous characterization of phytoplankton at the genus or species level. This semi-automatic classification requires a further validation by an experienced operator (performed at the Marine Observation Center in Ostende).

Zooplankton for the lifeWatch zooplankton observation in the Belgian part of the North Sea (https://doi.org/10.14284/394) are sampled by a 200µm mesh size WP2 plankton net (57 cm diameter opening ring) deployed vertically from bottom to surface in order to sample the whole water column at each station. The 200µm mesh size WP2 plankton net is the most commonly used and recognized method to sample mesozooplankon. The samples are then with fixed with formaldehyde and stored at the Marine Station in Ostende. The samples are processed with a ZooScan imaging system. The produced images are processed with the ZooProcess software allowing a semi-autonomous characterization of zooplankton into 22 validated taxonomic groups. This semi-automatic classification requires a further validation by an experienced operator (performed at the Marine Observation Center in Ostende).

Sampling by Niskin bottles on board RV Belgica. Laboratory analyses according to accredited method (ISO 17025) on the basis of SKALAR (RBINS, Ostend).