Summary
The phytoplankton genus Pseudochattonella spp.*, which is potentially harmful to fish when in high abundancies, was still blooming in the Kattegat and Skagerrak areas during the March cruise. The genus caused chlorophyll fluorescence maxima at several stations. The diatom spring bloom seems smaller than usual and it is possible that Pseudochattonella spp.* partially outcompeted it. Alternatively, the diatoms bloomed in between the cruises. The nutrients are close to consumed anyhow so it is not likely that any bloom will proceed for much longer. The spring bloom was just starting in the Southern Baltic in mid March. Several diatom species were observed at REF M1V1, of which Skeletonema marinoi and the genus Chaetoceros were abundant. S. marinoi was abundant at BY2 and BY5.