Removal of surface blooms of the cyanobacteria Nodularia spumigena: a pilot project conducted in the Baltic Sea.

Blooms of Cyanobacteria are a major concern during the summer period in the Baltic Sea Proper. The nitrogen-fixing Nodularia spumigena forms massive toxic blooms in the surface layers, with a concentration of biomass in the uppermost 1-m water layer. This pilot study describes the construction and test of a Nodularia collecting device during the summer of 2006. Oil booms were modified so that their dragging skirt was replaced with a water-permeable forming fabric used in the pulp and paper industry. The results showed that the modified oil booms worked and operated in an effective way when towed in the sea. Calculations showed that the collecting device used in this study has a theoretical capacity of cleaning 0.055 km2 (5.5 ha) of sea surface hr(-1), compared with the 6600 km2 of the Baltic Sea that were covered by Nodularia blooms during the summer of 2005. Future possibilities for Nodularia harvesting are discussed.