A temporal study of the phytoplankton spring bloom in Prince William Sound, Alaska

Abstract

The phytoplankton bloom in southwest Prince William Sound, Alaska began in early April, declined by May and had a small recovery in June 1995 and 1996. Phytoplankton bloom was nutrient-limited in April and phytoplankton biomass was controlled by zooplankton grazing in May. The bloom consisted of 80 % microplankton; the post bloom was predominandy flagellates, followed by a small diatom recovery. A seasonal succession in the diatom community occurred from Skeletonema costatum, Thalassiosira spp. and Chaetoceros spp. in April to Rhizosolenia fragilissima in June. There was little vertical variation in species composition. More than twice as much organic carbon due to phytoplankton was present in 1996 as in 1995. In 1995, Thalassiosira spp. was 73-80 % of diatom carbon and in 1996 Skeletonema costatum made up 58-78 %. The timing of the bloom, cell abundance and patterns of succession resembled other marine environments of similar latitude.