Distribution of planctomycete cells in the biofilm. Fluorescence microscopy images of Laminaria hyperborea surface biofilm. Images a, c, e and g show DAPI stained biofilm while b, d, f and h show FISH signals in the same microscope fields from hybridizations with either the Pla46 probe (b, d and f) or the Eub 338 I-III probe mix (h). Images show representative microscope fields of samples from July 2007 (a-b), September 2008 (c-d, g-h) and February 2007 (e-f). The enlarged inset image in b shows the typical ring shaped FISH signals of planctomycetes.