Phytoplankton is one of the four biological quality elements considered in the assessment of the ecological status/potential of natural water bodies. The phytoplankton-based assessment is carried out using five classes: high (blue), good (green), moderate (yellow), poor (orange), and bad (red). The assessment of the phytoplankton quality element is only relevant for large watercourses with a natural plankton content and for water bodies designated as heavily modified water bodies (HMWB) with stagnant-water characteristics. Consequently, phytoplankton is analysed only for surface water bodies of type VI, since the phytoplankton concentration in other river types is insufficient, and for the two HMWBs of the Sûre (MEsurf III-2.2.1) and the Our (MEsurf V-1.2), with an annual frequency of six samples taken between April and October.

Description copied from catalog.inspire.geoportail.lu.