Mixed species diatom bloom 7/12/2004, Beaufort Sea off Barrow, AK, slope station during Healy SBI spring cruise. Large diatom chains are pennate Fragillariopsis spp. Epifluorescence microscopy of DAPI stained samples. Red color is from chlorophyll autofluorescence. Blue color is DAPI-stained cell cytoplasm and cell nucleii. Also note long, thin pennate diatoms in this sample.