Studies on relationship between seasonal variation of phytoplankton community and environmental factors in the lower part of the Han River, Korea

Abstract

In order to understand seasonal variation of phytoplankton communities and environmental factors, the studies were carried out biweekly from February 2001 to February 2002, and from February 2004 to February 2005 in the lower the Han River. As a results, total of 437 taxa were identified and phytoplankton standing crops varied from 7.3 x 104cells mL-1to 4.2 x 106cells mL-1. The highest standing crops of phytoplankton community showed in winter and the lowest in summer. Among phytoplankton communities, abundance of diatoms and cyanobacteria occupied 73% and 14%, respectively, but green algae and euglenoids usually constituted approximate lower than 10% in total phytoplankton abundance. In winter, the diatom Stephanodiscus hanzschii was the key species with 61.5% of the total abundance. The other hand blue-green algae Oscllatoria limnosa showed blooming in the early spring. Asterionella fomosa, Chroococcus turgidus, Schroederia setigera and Spirogyra crassa occupied over 48% in the total phytoplankton abundance in spring. Peridinium cinctum and Cryptomonas sp. were dominated in the early summer. The diatom Aulacoseira species (A. ganulata, A. granulata var. angustissima and A. italic) was dominated during late summer to autumn. River. As a results, total of 437 taxa were identified and phytoplankton standing crops varied from 7.3 x 104cells mL-1to 4.2 x 106cells mL-1. The highest standing crops of phytoplankton community showed in winter and the lowest in summer. Among phytoplankton communities, abundance of diatoms and cyanobacteria occupied 73% and 14%, respectively, but green algae and euglenoids usually constituted approximate lower than 10% in total phytoplankton abundance. In winter, the diatom Stephanodiscus hanzschii was the key species with 61.5% of the total abundance. The other hand blue-green algae Oscllatoria limnosa showed blooming in the early spring. Asterionella fomosa, Chroococcus turgidus, Schroederia s