울릉도 주변해역의 식물플랑크톤 군집구조와 생체량의 계절변동

Abstract

To better understand seasonal variation in phytoplankton community structure in the coastal waters of Ulleung island, 4 research cruises were carried out between February and November 2015. Phytoplankton community structure and ambient seawater physicochemical parameters were examined. The phytoplankton community in the coastal waters of Ulleung island was mainly composed of diatoms and dinoflagellates, with 242 taxa in 70 genera of diatoms and 104 taxa in 26 genera of dinoflagellates. Several species of Chlorophyta, Chrysophyta, and Cyanophyta were also observed. Chain-forming diatoms were the most dominant phytoplankton the group throughout the year, except in summer when dinoflagellates dominated in the coastal waters. Phytoplankton abundance was always higher in coastal than offshore waters, which was mainly determined by availability of nutrient. Prorocentrum dentatum bloom and Chaetoceros debilis bloom were observed in the coastal waters during spring and autumn 2015, respectively. The blooms differed greatly in community diversity and cell standing crops distribution, potentially affecting the organic carbon export. In general, 3 different hydrographic water systems (coastal water, shelf mixed water, and offshore water) were identified from a temperature&#8722 salinity plot of the Ulleung island, and phytoplankton abundance showed spatial and temporal difference in the distribution patterns of the 3 water systater physicochemical parameters were examined. The phytoplankton community in the coastal waters of Ulleung island was mainly composed of diatoms and dinoflagellates, with 242 taxa in 70 genera of diatoms and 104 taxa in 26 genera of dinoflagellates. Several species of Chlorophyta, Chrysophyta, and Cyanophyta were also observed. Chain-forming diatoms were the most dominant phytoplankton the group throughout the year, except in summer when dinoflagellates dominated in the coastal waters. Phytoplankton abundance was always higher in coastal than offshore waters, which was mainly determined by availability of nutrient. Prorocentrum dentatum bloom and Chaetoceros debilis bloom were observed in the coastal waters during spring and autumn 2015, respectively. The blooms differed greatly in community diversity and cell standing crops distribution, potentially affecting the organic carbon export. In general, 3 different hydrographic water systems (coastal water, shelf mixed water, and offshore water) were identified from a temperature&#8722 salinity plot of the Ulleung island, and phytoplankton abundance showed spatial and temporal difference in the distribution patterns of the 3 water syst