Seasonal and spatial distribution of phytoplankton in the waters off Nuclear Power Plants, North of Taiwan

Abstract

Species composition of phytoplankton was monitored seasonally in the waters off the First and Second Nuclear Power plants (NPP1 and NPP2), north of Taiwan during 2001-2002. In total, 290 phytoplankton samples were collected and 265 taxa of phytoplankton were recorded. Chaetoceros compressas, Pseudo-nitzschia delicatissima, Skeletonema costatum, Thalassionema nitzschioides, and Lauderia annulata were the top five dominant species. Together they comprised 75% of the total phytoplankton cells. The species number and abundance of phytoplankton showed distinct seasonal, annual, and spatial changes, higher abundance in 2002 than 2001 and highest in August in both years and lowest in March in 2001 and in October in 2002. The highest species number and diversity were found in May 2002, the lowest species number in March 2001, and the lowest diversity in August 2002 that C. compressus dominated in the waters of NPP2 and Hwang River. The major dominant species of phytoplankton were similar but ranked differently between seasons and years. The abundance of phytoplankton generally decreased from inshore to offshore waters. The abundance and species number of phytoplankton were usually higher in the waters of NPP1 than that of NPP2 in 2001. but it was reverse in 2002. The effect of seasonal change in temperature on phytoplankton was significant in this study area, the abundance of phytoplankton generally increased with increasing temperature, but showed negative correlations with salinity and nutrients. The local topography and hydrography might play secondary roles to enhance the effect of temperature on phytoplankton, particularly in the waters of NPP2 and during summer.