![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
Abstract
The size composition of phytoplankton communities as measured by chlorophyll a concentration was studied in the subarctic, transition, and subtropical waters of the North Pacific Ocean in spring 1985. Total chlorophyll a concentration observed in surface water was lowest in the subtropical water (0.05 üg · l−1) wherein percent contribution of the <2 üm size fraction was largest (84%). Total chlorophyll a concentration higher than 1.0 üg · l−1 was observed in the subarctic water. In these waters, percent contribution of the > 10 üm size fraction was large (61%). However, even though in the subarctic water, the size composition in the water of the low chlorophyll a concentration (<1.0 üg · l−1) showed the importance of small size phytoplankton. In the subarctic water the temporal changes in the total chlorophyll a concentration mainly resulted from the variation of >10 üm size fraction. Diatoms were the major phytoplankters in the >10 üm size fraction that affected the regional and temporal variations of chlorophyll a concentration. It is concluded that the bloom of diatoms strongly affects the variation of phytoplankton biomass as well as size composition.