At station OF2 (59.186668 N, 10.691667 E) in the Skagerrak, samples of the subsurface (1m) pico- and nanoplankton were collected monthly for two years (September 2009-June 2011). 20L were prefiltered through 45 micron, and size-fractionated into 0.8-3 micron and 3-45 micron size fractions. The haptophytes were targeted by amplification of cDNA with haptophyte-specific SSU rDNA V4 primers Hap454 described in Egge et al. 2013 (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0074371).