The national monitoring program was initiated by the Swedish Environmental Protection Agency and is now financed by the Swedish Agency for Marine and Water Management. Monitoring is performed by Swedish Meteorological and Hydrological Institute and Umeå University. Data are stored in the Swedish Ocean Archive database (SHARK), by the Swedish Meteorological and Hydrological Institute. Data should be sampled and analyzed according to MacIsaac E A and Stockner J G 1993. Enumeration of phototrophic picoplankton by autoflourescence microscopy. In Handbook of methods in aquatic microbial ecology. Kemp P F, Sherr B F, Sherr E B, and Cole J J (eds.) Lewis, Boca Raton. pp. 187-197. However, deviations from the manual might occur.